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PHYSICS (564 journals)            First | 1 2 3 4 5 6 | Last

Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
Noise Notes     Full-text available via subscription   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 9)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 10)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 4)
Open Journal of Microphysics     Open Access  
Open Physics     Open Access   (Followers: 2)
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 5)
Optofluidics, Microfluidics and Nanofluidics     Open Access   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 4)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 12)
Papers in Physics     Open Access  
Particle Physics Insights     Open Access   (Followers: 2)
Particuology     Hybrid Journal  
Pattern Recognition in Physics     Open Access   (Followers: 2)
Pergamon Materials Series     Full-text available via subscription  
Phase Transitions and Critical Phenomena     Full-text available via subscription   (Followers: 1)
Philosophical Magazine     Hybrid Journal   (Followers: 2)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 6)
Philosophy and Foundations of Physics     Full-text available via subscription  
Physica B: Condensed Matter     Hybrid Journal   (Followers: 5)
physica status solidi (a)     Hybrid Journal   (Followers: 1)
physica status solidi (b)     Hybrid Journal   (Followers: 1)
physica status solidi (c)     Hybrid Journal   (Followers: 1)
Physica Status Solidi - Rapid Research Letters     Hybrid Journal   (Followers: 1)
Physical Communication     Hybrid Journal   (Followers: 2)
Physical Review C     Full-text available via subscription   (Followers: 19)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 7)
Physical Sciences Data     Full-text available via subscription   (Followers: 1)
Physics - spotlighting exceptional research     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 3)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 2)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 3)
Physics and Materials Chemistry     Open Access  
Physics Essays     Full-text available via subscription   (Followers: 1)
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 10)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
Physics Letters A     Hybrid Journal   (Followers: 9)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 28)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 7)
Physics of the Dark Universe     Open Access   (Followers: 1)
Physics of the Solid State     Hybrid Journal   (Followers: 3)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics Procedia     Partially Free   (Followers: 1)
Physics Reports     Full-text available via subscription   (Followers: 2)
Physics Research International     Open Access   (Followers: 1)
Physics Today     Hybrid Journal   (Followers: 37)
Physics World     Full-text available via subscription   (Followers: 3)
Physics-Uspekhi     Full-text available via subscription  
Physik in unserer Zeit     Hybrid Journal   (Followers: 1)
Physik Journal     Hybrid Journal  
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 3)
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Pramana     Open Access   (Followers: 9)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 475)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 21)
Progress in Planning     Hybrid Journal   (Followers: 1)
Progress of Theoretical and Experimental Physics     Open Access  
Quantum Electronics     Full-text available via subscription   (Followers: 3)
Quantum Measurements and Quantum Metrology     Open Access  
Quantum Studies : Mathematics and Foundations     Hybrid Journal   (Followers: 1)
Quarterly Journal of Mechanics and Applied Mathematics     Hybrid Journal   (Followers: 3)
Radiation Effects and Defects in Solids     Hybrid Journal   (Followers: 1)
Radiation Measurements     Hybrid Journal   (Followers: 2)
Radiation Physics and Chemistry     Hybrid Journal   (Followers: 1)
Radiation Protection Dosimetry     Hybrid Journal   (Followers: 2)
Radiation Research     Full-text available via subscription   (Followers: 3)
Radio Science     Full-text available via subscription   (Followers: 3)
Radiological Physics and Technology     Hybrid Journal   (Followers: 1)
Reflets de la physique     Full-text available via subscription  
Reports on Mathematical Physics     Full-text available via subscription  
Reports on Progress in Physics     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Physics     Full-text available via subscription  
Research in Drama Education     Hybrid Journal   (Followers: 12)
Research Journal of Physics     Open Access  
Results in Physics     Open Access   (Followers: 1)
Reviews in Mathematical Physics     Hybrid Journal  
Reviews of Accelerator Science and Technology     Hybrid Journal  
Reviews of Geophysics     Full-text available via subscription   (Followers: 20)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 17)
Revista Boliviana de Física     Open Access  
Revista Colombiana de Física     Open Access  
Revista Mexicana de Astronomía y Astrofísica     Open Access  
Revista Mexicana de Física     Open Access  
Revista mexicana de física E     Open Access  
Rheologica Acta     Hybrid Journal   (Followers: 3)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal  

  First | 1 2 3 4 5 6 | Last

Journal Cover   Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.624]   [H-I: 42]   [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [2798 journals]
  • Impacts of sparing use of water on farmer income of China
    • Abstract: Publication date: Available online 25 September 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhan Wang, Xiangzheng Deng, Jiancheng Chen
      we examine relationships between nationwide sparing use of water and farmer income of China in this article. As increasing implementation of water projects and irrigation system, the cost of water use has increased and many regions. However, as local policy-oriented urban expansion and ecological restoration have carried out during the past decade, water demand has increased. The spatial distributions of water use and farmer income are uneven and their relationships are ambiguous over time, especially it is uncertain that farmers can benefit from those so called water-saving programs when urban expansion grows faster in China. Based on consumption theory, empirical results of Blundell-Bond dynamic panel-data model with generalized method of moments (GMM) estimators indicate saving one percent of water has positive impacts at 0.085∼0.35 percent on farmer income in the following statistical year. Population has negative impacts on farmer income. Particularly in Central China, one percent of increase in population will significantly decrease 0.276 percent of contemporaneous farmer income. Particularly, in Eastern China with large population during years 2004 through 2012, the total amount of water use increases one percent, contemporaneous farmer income loses 0.04 percent. Thus, saving water can benefit future farmer income, and it indicates that urban expansion may induce the diversion of resources for agricultural production from rural to urban area. Policy implication of relationships between water allocation and farmer income distribution caused by water-saving programs needs to be further studied at regional scale, in particularly to the regions with large population and urban expansion in China.

      PubDate: 2015-09-25T23:24:44Z
  • Polarimetric scattering model for estimation of above ground biomass of
           multilayer vegetation using ALOS-PALSAR quad-pol data
    • Abstract: Publication date: Available online 25 September 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): P. Sai Bharadwaj, Shashi Kumar, S.P.S. Kushwaha, Wietske Bijker
      Forests are important biomes covering a major part of the vegetation on the Earth, and as such account for seventy percent of the carbon present in living beings. The value of a forest’s above ground biomass (AGB) is considered as an important parameter for the estimation of global carbon content. In the present study, the quad-pol ALOS - PALSAR data was used for the estimation of AGB for the Dudhwa National Park, India. For this purpose, polarimetric decomposition components and an Extended Water Cloud Model (EWCM) were used. The PolSAR data orientation angle shifts were compensated for before the polarimetric decomposition. The scattering components obtained from the polarimetric decomposition were used in the Water Cloud Model (WCM). The WCM was extended for higher order interactions like double bounce scattering. The parameters of the EWCM were retrieved using the field measurements and the decomposition components. Finally, the relationship between the estimated AGB and measured AGB was assessed. The coefficient of determination (R2) and root mean square error (RMSE) were 0.4341 and 119 t/ha respectively.

      PubDate: 2015-09-25T23:24:44Z
  • Notable shifting in the responses of vegetation activity to climate change
           in China
    • Abstract: Publication date: Available online 4 September 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aifang Chen, Bin He, Honglin Wang, Ling Huang, Yunhua Zhu
      The weakening relationship between inter-annual temperature variability and vegetation activity in the Northern Hemisphere over the last three decades has been reported by a recent study. However, how and to what extent vegetation activity responds to climate change in China is still unclear. We applied the Pearson correlation and partial correlation methods with a moving 15-y window to the GIMMS NDVI dataset from NOAA/AVHRR and observed climate data to examine the variation in the relationships between vegetation activity and climate variables. Results showed that there was an expanding negative response of vegetation growth to climate warming and a positive role of precipitation. The change patterns between NDVI and climate variables over vegetation types during the past three decades pointed an expending negative correlation between NDVI and temperature and a positive role of precipitation over most of the vegetation types (meadow, grassland, shrub, desert, cropland, and forest). Specifically, correlation between NDVI and temperature (PNDVI-T) have shifted from positive to negative in most of the station of temperature-limited areas with evergreen broadleaf forests, whereas precipitation-limited temperate grassland and desert were characterized by a positive PNDVI-P. This study contributes to ongoing investigations of the effects of climate change on vegetation activity. It is also of great importance for designing forest management strategies to cope with climate change.

      PubDate: 2015-09-06T06:42:56Z
  • Estimation of maize yield by using a process-based model and remote
           sensing data in the Northeast China Plain
    • Abstract: Publication date: Available online 1 September 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Fengmei Yao, Yanjing Tang, Peijuan Wang, Jiahua Zhang
      Climate change significantly impact on agriculture in recent year, the accurate estimation of crop yield is of great importance for the food security. In this study, a process-based mechanism model was modified to estimate yield of C4 crop by modifying the carbon metabolic pathway in the photosynthesis sub-module of the RS–P–YEC (Remote-Sensing–Photosynthesis–Yield estimation for Crops) model. The yield was calculated by multiplying net primary productivity (NPP) and the harvest index (HI) derived from the ratio of grain to stalk yield. The modified RS–P–YEC model was used to simulate maize yield in the Northeast China Plain during the period 2002–2011. The 111 statistical data of maize yield from study area was used to validate the simulated results at county-level. The results showed that the Pearson correlation coefficient (R) was 0.827 (p <0.01) between the simulated yield and the statistical data, and the root mean square error (RMSE) was 712kg/ha with a relative error (RE) of 9.3%. From 2002 to 2011, the yield of maize planting zone in the Northeast China Plain was increasing with smaller coefficient of variation (CV). The spatial pattern of simulated maize yield was consistent with the actual distribution in the Northeast China Plain, with an increasing trend from the northeast to the southwest. Hence the results demonstrated that the modified process-based model coupled with remote sensing data was suitable for yield prediction of maize in the Northeast China Plain at the spatial scale.

      PubDate: 2015-09-06T06:42:56Z
  • Analysis of observations backing up the existence of VLF and ionospheric
           TEC anomalies before the Mw6.1 earthquake in Greece, January 26, 2014
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): F. Sanchez-Dulcet, M. Rodríguez-Bouza, H.G. Silva, M. Herraiz, M. Bezzeghoud, P.F. Biagi
      The present work integrates ground-based ionosphere measurements using very-low-frequency radio transmissions with satellite measurements of the total electron content to draw common conclusions about the possible impact that the Mw6.1 earthquake that took place in Greece on January 26, 2014, had on the ionosphere. Very-low-frequency radio signals reveal the existence of an ∼4-day anomaly in the wavelet spectra of the signals received inside the earthquake preparation zone and a significant increase in the normalized variance of the signals prior to the earthquake (approximately 1 day before). Through total electron content analysis, it was possible to identify a clear anomaly from 15:00 until 20:00 UT on the day before the earthquake that appears again on the day of the earthquake between 07:00 UT and 08:00 UT. The anomalous values reach TEC∗Sigma ∼ 4.36 and 3.11, respectively. Their spatial and temporal distributions give grounds to assume a possible link with the earthquake preparation. The geomagnetic, solar and weather conditions during the considered period are presented and taken into account. This work is an initial and original step towards a multi-parameter approach to the problem of the possible earthquake-related effects on the ionosphere joining observations made from both ground stations and satellites. A well-founded knowledge of these phenomena is clearly necessary before dealing with their application to earthquake prediction purposes.

      PubDate: 2015-08-31T06:09:29Z
  • Evaluation of DEM generation based on Interferometric SAR using TanDEM-X
           data in Tokyo
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ram Avtar, Ali P Yunus, Steven Kraines, Masumi Yamamuro
      This study is focused on the evaluation of a Digital Elevation Model (DEM) for Tokyo, Japan from data collected by the recently launched TerraSAR add-on for Digital Elevation Measurements (TanDEM-X), satellite of the German Aerospace Center (DLR). The aim of the TanDEM-X mission is to use Interferometric SAR techniques to generate a consistent high resolution global DEM dataset. In order to generate an accurate global DEM using TanDEM-X data, it is important to evaluate the accuracy at different sites around the world. Here, we report our efforts to generate a high-resolution DEM of the Tokyo metropolitan region using TanDEM-X data. We also compare the TanDEM-X DEM with other existing DEMs for the Tokyo region. Statistical techniques were used to calculate the elevation differences between the TanDEM-X DEM and the reference data. Two high-resolution reference DEMs are used as independent reference data. The vertical accuracy of the TanDEM-X DEM evaluated using the Root Mean Square Error (RMSE) is considerably higher than the existing global digital elevation models. However, the local area DEM generated by Geospatial Information Authority of Japan (GSI DEM) showed the highest accuracy among all non-LiDAR DEM’s. The vertical accuracy in terms of RMSE estimated using the 2 m LiDAR as reference is 3.20 m for TanDEM-X, 2.44 m for the GSI, 7.00 m for SRTM DEM and 10.24 m for ASTER-GDEM. We also compared the accuracy of TanDEM-X with the other DEMs for different types of land cover classes. The results show that the absolute elevation error of TanDEM-X is higher for urban and vegetated areas, likewise to those observed for other global DEM’s. This is probably because the radar signals used by TanDEM-X tend to measure the first reflective surface that is encountered, which is often the top of the buildings or canopy. Hence, the TanDEM-X based DEM is more akin to a Digital Surface Model (DSM).

      PubDate: 2015-08-31T06:09:29Z
  • Climate threats, water supply vulnerability and the risk of a water crisis
           in the Monterrey Metropolitan Area (Northeastern Mexico)
    • Abstract: Publication date: Available online 29 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Nicholas P. Sisto, Aldo I. Ramírez, Ismael Aguilar-Barajas, Víctor Magaña-Rueda
      This paper evaluates the risk of a water crisis – a substantial, sudden reduction in water supply - in the Monterrey Metropolitan Area (MMA), posed by climate threats and the vulnerability of its water supply system. Our analysis of long-term precipitation, water supply and water availability data reveals that the MMA is highly vulnerable to recurring periods of exceptionally low precipitation and scarce surface water availability. We identify two episodes in the recent past (1998 and 2013) when the MMA water supply system almost collapsed as reservoirs neared depletion in the face of abnormally dry weather. Furthermore our climate projections point to warmer and drier future conditions for the region and consequently, heightened climate threats. We conclude that the risk of a water crisis in the MMA is substantial and probably will increase due to climate change. This establishes a clear and pressing need for a comprehensive package of adaptation measures to mitigate the consequences of a water crisis should one occur as well as to reduce the likelihood of such an event.

      PubDate: 2015-08-31T06:09:29Z
  • Possible Climate Change Evidence in Ten Mexican Watersheds
    • Abstract: Publication date: Available online 29 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Efrain Mateos, Julio-Sergio Santana, Martin J Montero-Martínez, Alejandro Deeb, Alfred Grunwaldt
      This paper suggests possible evidence of climate change in Mexico at the watershed level, based solely on historical data. The official Mexican climate dataset was used to find the best set of stations for each watershed. Maximum and minimum temperatures and rainfall in ten watersheds are analyzed from 1970 to 2009. Maximum temperature trends show a significant increment in most of these watersheds. Furthermore, Daily Temperature Range (DTR) exhibits a positive trend (increments), thus implying an increase in temperature extremes. This study also shows that the difference between maximum and minimum monthly temperature trends is negatively correlated with monthly precipitation trends. As a result, land-use and land-cover changes could be the main drivers of climate change in the region.

      PubDate: 2015-08-31T06:09:29Z
  • Exploring the dynamics of agricultural climatic resource utilization of
           spring maize over the past 50years in Northeast China
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Junfang Zhao, Jianping Guo, Jia Mu, Yanhong Xu
      Exploring the dynamics of the utilization of agricultural climatic resources (i.e., environmental factors that affect crop productivity such as light, temperature, and water) can provide a theoretical basis for modifying agricultural practices and distributions of agricultural production in the future. Northeast China is one of the major agricultural production areas in China and also an obvious region of climatic warming. We were motivated to analyze the utilization dynamics of agricultural climatic resource during spring maize cultivation from 1961 to 2010 in Northeast China. To understand these dynamics, we used the daily data from 101 meteorological stations in Northeast China between 1961 and 2010. The demands on agricultural climatic resources in Northeast China imposed by the cultivation of spring maize were combined and agricultural climatic suitability theory was applied. The growth period of spring maize was further detailedly divided into four stages: germination to emergence, emergence to jointing, jointing to tasseling, and tasseling to maturity. The average resource utilization index was established to evaluate the effects. Over the past five decades, Northeast China experienced increases in daily average temperature of 0.246°C every decade during the growing season (May–September). At the same time, strong fluctuating decreases were observed in average total precipitation of 8.936mm every decade and an average sunshine hour of 0.122h every decade. Significant temporal and spatial changes occurred in K from 1961 to 2010. The K showed decreasing trends in Liaoning province and increasing trends in Jilin and especially in Heilongjiang province, which increased by 0.11. Spatial differences were visible in different periods, and the most obvious increase was found in the period 2001–2010. The areas with high values of K shifted northeastward over the past 50years, indicating more efficient use of agricultural climatic resources in Northeast China.

      PubDate: 2015-08-31T06:09:29Z
  • Adjustment of wind-drift effect for real-time systematic error correction
           in radar rainfall data
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qiang Dai, Dawei Han, Lu Zhuo, Jing Huang, Tanvir Islam, Shuliang Zhang
      An effective bias correction procedure using gauge measurement is a significant step for radar data processing to reduce the systematic error in hydrological applications. In these bias correction methods, the spatial matching of precipitation patterns between radar and gauge networks is an important premise. However, the wind-drift effect on radar measurement induces an inconsistent spatial relationship between radar and gauge measurements as the raindrops observed by radar do not fall vertically to the ground. Consequently, a rain gauge does not correspond to the radar pixel based on the projected location of the radar beam. In this study, we introduce an adjustment method to incorporate the wind-drift effect into a bias correlation scheme. We first simulate the trajectory of raindrops in the air using downscaled three-dimensional wind data from the weather research and forecasting model (WRF) and calculate the final location of raindrops on the ground. The displacement of rainfall is then estimated and a radar–gauge spatial relationship is reconstructed. Based on this, the local real-time biases of the bin-average radar data were estimated for 12 selected events. Then, the reference mean local gauge rainfall, mean local bias, and adjusted radar rainfall calculated with and without consideration of the wind-drift effect are compared for different events and locations. There are considerable differences for three estimators, indicating that wind drift has a considerable impact on the real-time radar bias correction. Based on these facts, we suggest bias correction schemes based on the spatial correlation between radar and gauge measurements should consider the adjustment of the wind-drift effect and the proposed adjustment method is a promising solution to achieve this.

      PubDate: 2015-08-31T06:09:29Z
  • Review and discussion of homogenisation methods for climate data
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S. Ribeiro, J. Caineta, A.C. Costa
      The quality of climate data is of extreme relevance, since these data are used in many different contexts. However, few climate time series are free from non-natural irregularities. These inhomogeneities are related to the process of collecting, digitising, processing, transferring, storing and transmitting climate data series. For instance, they can be caused by changes of measuring instrumentation, observing practices or relocation of weather stations. In order to avoid errors and bias in the results of analysis that use those data, it is particularly important to detect and remove those non-natural irregularities prior to their use. Moreover, due to the increase of storage capacity, the recent gathering of massive amounts of weather data implies also a toilsome effort to guarantee its quality. The process of detection and correction of irregularities is named homogenisation. A comprehensive summary and description of the available homogenisation methods is critical to climatologists and other experts, who are looking for a homogenisation method wholly considered as the best. The effectiveness of homogenisation methods depends on the type, temporal resolution and spatial variability of the climatic variable. Several comparison studies have been published so far. However, due to the absence of time series where irregularities are known, only a few of those comparisons indicate the level of success of the homogenisation methods. This article reviews the characteristics of the most important procedures used in the homogenisation of climatic variables based on a thorough literature research. It also summarises many methods applications in order to illustrate their applicability, which may help climatologists and other experts to identify adequate method(s) for their particular needs. This review study also describes comparison studies, which evaluated the efficiency of homogenisation methods, and provides a summary of conclusions and lessons learned regarding good practices for the use of homogenisation methods.

      PubDate: 2015-08-31T06:09:29Z
  • Geochemical modelling and speciation studies of metal pollutants present
           in selected water systems in South Africa
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.M. Magu, P.P. Govender, J.C. Ngila
      Metal pollutants in water poses great threats to living beings and hence requires to be monitored regularly to avoid loss of lives. Various analytical methods are available to monitor these pollutants in water and can be improved with time. Modelling of metal pollutants in any water system helps chemists, engineers and environmentalists to greatly understand the various chemical processes in such systems. Water samples were collected from waste water treatment plant and river from highlands close to its source all the way to the ocean as it passing through areas with high anthropogenic activities. Pre-concentration of pollutants in the samples was done through acid digestion and metal pollutants were analysed using inductively coupled plasma-optical emission spectra (ICP-OES) to determine the concentration levels. Metal concentrations ranged between 0.1356–0.4658mg/L for Al; 0.0031–0.0050mg/L for Co, 0.0019–0.0956mg/L for Cr; 0.0028–0.3484mg/L for Cu; 0.0489–0.3474mg/L for Fe; 0.0033–0.0285mg/L for Mn; 0.0056–0.0222mg/L for Ni; 0.0265–0.4753mg/L for Pb and 0.0052–0.5594mg/L for Zn. Modelling work was performed using PHREEQC couple with Geochemist’s workbench (GWB) to determine speciation dynamics and bioavailability of these pollutants. Modelling thus adds value to analytical methods and hence a better complementary tool to laboratory-based experimental studies.

      PubDate: 2015-08-31T06:09:29Z
  • Simulated effects of cropland expansion on seasonal temperatures over
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhe Xiong
      Human activities result in deforestation, expansion of cropland, grassland degradation, urbanization and other large-scale land use/cover change; among these, cropland expansion is one of the most important processes. To understand the effects of cropland expansion on seasonal temperatures over China, two 21-year simulations (spanning January 1, 1980–December 31, 2000), using the Regional Integrated Environmental Model System (RIEMS 2.0), were performed. The two simulations comprised current realistic land use/cover patterns and the previous vegetation cover without crop expansion, to investigate the impact of crop expansion on seasonal temperatures over China. The results showed that due to cropland expansion: (1) the most obvious changes occurred in the maximum temperatures, followed by the mean surface air temperatures, and the minimum temperatures were the least affected; (2) the summer mean maximum temperatures decreased in most parts of eastern China, and the temperatures changed significantly in most parts of northeast China, north China and central China (p < 0.05); (3) the surface air temperatures, maximum temperatures and minimum temperatures in summer decreased in the different regions by between −0.03 and −0.76°C (the greatest temperature changes occurred in southwest China, and the smallest were in northeast China); (4) the net radiation flux and latent heat flux increased, while the sensible flux decreased, when semi-desert vegetation was replaced by dry land crops, in both summer and winter seasons, and the converse occurred when irrigated crops were replaced by dry land crops. In addition, the net radiation flux and sensible heat flux decreased, and the latent heat flux increased when short grass and tall grass were replaced dry land crops, as well as when dry land crops were replaced by irrigated crops.

      PubDate: 2015-08-31T06:09:29Z
  • Quantitative Analysis of Agricultural Land Use Change in China
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Chou Jieming, Dong Wenjie, Wang Shuyu, Fu Yuqing
      This article reviews the potential impacts of climate change on land use change in China. Crop Sown Area is used as index to quantitatively analyze the temporal-spatial changes and the utilization of the agricultural land. A new concept is defined as potential multiple cropping index to reflect the potential sowing ability. The impacting mechanism, land use status and its surplus capacity are investigated as well. The main conclusions are as following; 1. During 1949 to 2010, the agricultural land was the greatest in amount in the middle of China, followed by that in the country’s eastern and western regions. The most rapid increase and decrease of agricultural land were observed in Xinjiang and North China respectively, Northwest China and South China is also changed rapid. The variation trend before 1980 differed significantly from that after 1980. 2. Agricultural land was affected by both natural and social factors, such as regional climate and environmental changes, population growth, economic development, and implementation of policies. In this paper, the effects of temperature and urbanization on the coverage of agriculture land are evaluated, and the results show that the urbanization can greatly affects the amount of agriculture land in South China, Northeast China, Xinjiang and Southwest China. 3. From 1980 to 2009, the extent of agricultural land use had increased as the surplus capacity had decreased. Still, large remaining potential space is available, but the future utilization of agricultural land should be carried out with scientific planning and management for the sustainable development.

      PubDate: 2015-08-31T06:09:29Z
  • Impacts of temperature on rice yields of different rice cultivation
           systems in Southern China over the past 40 years
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jiahua Zhang, Fengmei Yao, Cui Hao, Vijendra Boken
      The impact of climate change on rice yield in China remains highly uncertain. we examined the impact of the change of maximum temperature (T max) and minimum temperature (T min) on rice yields in southern China from 1967 to 2007. The rice yields were simulated by using the DSSAT3.5 (Decision Support System for Agro-technology Transfer)-Rice model. The change of T max and T min in rice growing seasons and simulated rice yields as well their correlations were analyzed. The simulated yields of middle rice and early rice had a decreasing trend, but late rice yields showed a weak rise trend. There was significant negative correlation between T max and the early rice yields, as well as the late rice yieldsin most stations, but non-significant negative correlation for the middle rice yields. An obviously negative relationship was found between T min and the early and middle rice yields, and a significant positive relationship was found between T min and the late rice yields. It indicated that under the recent climate warming, the increasedT max brought strong negative impacts on early rice yields and late rice yields, but a weak negative impact on the middle rice yields; the increased T min had a strong negative impact on the middle rice yields and the early rice yields, but a significant positive impact on the late rice yields. It suggested that it is necessary to adjust rice planting date and adapt to higher T min.

      PubDate: 2015-08-31T06:09:29Z
  • Contribution of surface roughness to simulations of historical
    • Abstract: Publication date: Available online 29 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ye Wang, Zhaomin Wang
      Surface roughness which partitions surface net radiation into energy fluxes is a key parameter for estimation of biosphere-atmosphere interactions and climate variability. An earth system model of intermediate complexity (EMIC), MPM-2, is used to derive the impact of surface roughness on climate from simulations of historical land cover change effects. The direct change in surface roughness leads to a global surface warming of 0.08°C through altering the turbulence in the boundary layer. The regional temperature response to surface roughness associated deforestation is very strong at northern mid-latitudes with a most prominent warming of 0.72°C around 50°N in the Eurasia continent during summer. They can be explained mainly as direct and indirect consequences of decreases in surface albedo and increases in precipitation in response to deforestation, although there are a few significant changes in precipitation. There is also a prominent warming of 0.25°C around 40°N in the North American continent. This study indicates that land surface roughness plays a significant role which is comparable with the whole land conversion effect in climate change. Therefore, further investigation of roughness-climate relationship is needed to incorporate these aspects.

      PubDate: 2015-08-31T06:09:29Z
  • Expansion of agricultural oasis in the Heihe River Basin of China:
           patterns, reasons and policy implications
    • Abstract: Publication date: Available online 24 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Wei Song, Ying Zhang
      The Heihe River Basin (HRB) is the second largest inland river basin in the arid region of northwestern China. An agricultural oasis is a typical landscape in arid regions providing precious fertile soil, livingspace and ecological services. The agricultural oasis change has been one of the key issues in sustainable development in recent decades. In this paper, we examined the changes in the agricultural oasis in HRB and analyzed the socio-economic and climatic driving forces behind them. It was found that the agricultural oasis in HRB expanded by 25.11% and 14.82% during the periods of 1986–2000 and 2000–2011, respectively. Most of the newly added agricultural oases in HRB were converted from grassland (40.94%) and unused land (40.22%). The expansion in the agricultural oasis mainly occurred in the middle reaches of HRB, particularly in the counties of Shandan, Minle, Jinta and Jiuquan city. Changes in the rural labor force, annual temperature and precipitation have significant positive effects on agricultural oasis changes, while the ratio of irrigated agricultural oases has significant negative effects on agricultural oasis changes. The agricultural oasis expansion in HRB is the combined effect of human activity and climate change.

      PubDate: 2015-08-27T05:37:37Z
  • New Criteria to Assess Interbasin Water Transfers and a Case for Nzoia-
           Suam/Turkwel in Kenya
    • Abstract: Publication date: Available online 24 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Joel Kibiiy, Julius Ndambuki
      Although an interbasin water transfer project (IWT) is subject to many issues ranging from socio-economic to ecological, the final decision on implementation is always a political one, made in the best interest of sitting administrations. Therefore a sound pragmatic assessment process for IWTs should be used to inform the final (political) decision. Unfortunately, there is no universally agreed set of criteria for assessment of IWTs. Existing criteria vary and tend to be prescriptive and subjective. In addition, the assessment is often further complicated by paucity of data and transboundary issues. This paper proposes an evaluation approach that guarantees internal objectivity for specific projects. It is based on three basic requirements, firstly, the need to objectively justify the project, secondly, the need to show that the adverse effects of the project are minimized, and thirdly, the need to show that the expected benefits are maximized. Assessment of the sustainability of a project is made by tree-branching the three basic requirements and assigning an equal weight, a positive or a negative mark, to sub-branches at the highest branch level reached. A positive mark is given for an issue deemed to favour implementation of a project, or otherwise a negative mark. The final score for decision making is the percentage of the positive marks to the total marks. This method is demonstrated on a proposed IWT from the water-rich Nzoia River basin to the existing Turkwel Gorge Reservoir in the water-deficit Suam/Turkwel River basin, both in Kenya but having international issues.

      PubDate: 2015-08-27T05:37:37Z
  • Water ecological carrying capacity of urban lakes in the context of rapid
           urbanization: a case study of East Lake in Wuhan
    • Abstract: Publication date: Available online 15 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lei Ding, Kun-lun Chen, Sheng-gao Cheng, Xu Wang
      With the excessive development of social economy, water scarcity and water environment deterioration become a common phenomenon in metropolis. As a crucial component of urban water environment system, urban lake is mainly influenced by social economic system and tourism system. In this paper, a framework for quantitatively evaluating development sustainability of urban lake was established by a multi-objective model that represented water ecological carrying capacity (WECC). And nine key indicators including population, irrigation area, tourist quantity, the average number of hotel daily reception, TP, TN, CODMn, BOD5 were chosen from urban social-economy system and natural resilience aspects, with their index weight was determined by using the structure entropy weight method. Then, we took Wuhan East Lake, the largest urban lake in China as a case study, and selected five time sections including 2002, 2004, 2007, 2009 and 2012 to synthetically evaluate and comparatively analyze the dynamic change of WECC. The results showed that: firstly, the water ecological carrying capacity values of the East Lake in five time sections were 1.17, 1.07, 1.64, 1.53 and 2.01 respectively, which all exceeded 1 and increased fluctuation. The rapid growth of population and GDP lead to sharply increasing demand for water quantity. However, a large amount of the domestic sewage and industrial waste led by economic development increases pressure on ecological environment of urban lakes. Secondly, the carrying capacity of the East Lake for tourist activities was still low. The value in 2012 was only 0.22, keeping at a slowly increasing phase, which indicates that the East Lake has large opportunity and space for developing the water resource carrying capacity and could make further efforts to attract tourists. Moreover, the WECC of the East Lake was mainly affected by rapid social and economic development and water environment damage caused by organic pollutants. From the view of urban water sustainable management, we must deeply recognize the reality that water shortages and the limited carrying capacity, and dynamic assessment of WECC provides an early warning approach and control direction of water environment. For the East Lake, it is the primary target to mitigate the carrying capacity of social-economy, especially for prevention of lake area encroachment shrinking and domestic wastewater discharge.

      PubDate: 2015-08-19T05:31:00Z
  • Spatial and Temporal changes of phosphorus in coastal wetland soils as
           affected by a tidal creek in the Yellow River Estuary, China
    • Abstract: Publication date: Available online 15 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhaoqin Gao, Junhong Bai, Jia Jia, Xiaojun Wen, Guangliang Zhang, Qingqing Zhao
      In order to investigate spatial and temporal changes of soil phosphorus and its availability in coastal wetlands in the Yellow River Estuary, soil samples from five sampling sites (Sites1-5) in four sampling periods were collected and the contents of soil phosphorus and other properties were detected. Our results showed that there were no significant differences in total phosphorus (TP) in surface and subsurface soils among the five sampling sites (p>0.05), whereas significant differences were observed between June and other months (p<0.05) following the order June > August > November > April. Generally, available phosphorus (AP) contents also showed a fluctuation in different sampling periods and there were significant differences between November and August and April at 10-20 cm soil layer (p<0.05). The soil P supply was generally lower with lower AP: TP ratios less than 2%. Spatial changes along the sampling belt in AP: TP ratios were similar in surface soils except for April, whereas they decreased in subsurface soils in June and November, and fluctuated slightly in August and April. Lower C: P ratios (<50) in coastal wetland soils contributed to soil P mineralization. Spatial changes in the C: P ratios were similar the surface soils in four sampling periods, and the reverse changing tendencies were observed in subsurface soils between April and June and between August and November. Correlation analysis showed that TP had significant positive correlations with Al, Mg and bulk density and negative correlations with soil moisture and C: P ratio (p < 0.01). Comparatively, AP was just significantly correlated with soil organic matter. The findings indicated that seasonal changes in soil P should be given more concerns to minimize the eutrophication risk of water bodies in coastal wetlands and guide the flow and sediment regulation regime of the upstream reservoir.

      PubDate: 2015-08-19T05:31:00Z
  • Reducing atmospheric noise in RST analysis of TIR satellite radiances for
           earthquakes prone areas satellite monitoring
    • Abstract: Publication date: Available online 19 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mariano Lisi, Carolina Filizzola, Nicola Genzano, Rossana Paciello, Nicola Pergola, Valerio Tramutoli
      Space-time fluctuations of the Earth’s emitted Thermal Infrared (TIR) radiation observed from satellite from months to weeks before an earthquake are reported in several studies. Among the others, a Robust Satellite data analysis Technique (RST) was proposed (and applied to different satellite sensors in various geo-tectonic contexts) to discriminate anomalous signal transients possibly associated with earthquake occurrence from normal TIR signal fluctuations due to other possible causes (e.g. solar diurnal-annual cycle, meteorological conditions, changes in observational conditions, etc.). Variations in satellite view angle depending on satellite’s passages (for polar satellites) and atmospheric water vapour fluctuations were recognized in the past as the main factors affecting the residual signal variability reducing the overall Signal-to-Noise (S/N) ratio and the potential of the RST-based approach in identifying seismically related thermal anomalies. In this paper we focus on both factors for the first time, applying the RST approach to geostationary satellites (which guarantees stable view angles) and using Land Surface Temperature (LST) data products (which are less affected by atmospheric water vapour variability) instead of just TIR radiances at the sensor. The first results, obtained in the case of the Abruzzo earthquake (6 April 2009, MW∼6.3) by analyzing 6 years of SEVIRI (Spinning Enhanced Visible and Infrared Imager on board the geostationary Meteosat Second Generation satellite) LST products provided by EUMETSAT, seem to confirm the major sensitivity of the proposed approach in detecting perturbations of the Earth’s thermal emission a few days before the main shock. The results achieved in terms of increased S/N ratio (in validation) and reduced “false alarms” rate (in confutation) are discussed comparing results obtained by applying RST to LST products with those achieved by applying an identical RST analysis (using the same MSG-SEVIRI 2005-2010 data-set) to the simple TIR radiances at the sensor.

      PubDate: 2015-08-19T05:31:00Z
  • Decline in the species richness contribution of Echinodermata to the
           macrobenthos in the shelf seas of China
    • Abstract: Publication date: Available online 14 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Shaofei Jin, Yongli Wang, Jiangjiang Xia, Ning Xiao, Junlong Zhang, Zhe Xiong
      Echinoderms play crucial roles in the structure of marine macrobenthic communities. They are sensitive to excess absorption of CO2 by the ocean, which induces ocean acidification and ocean warming. In the shelf seas of China, the mean sea surface temperature has a faster warming rate compared with the mean rate of the global ocean, and the apparent decrease in pH is due not only to the increased CO2 absorption in seawater, but also eutrophication. However, little is known about the associated changes in the diversity of echinoderms and their roles in macrobenthic communities in the seas of China. In this study, we conducted a meta-analysis of 77 case studies in 51 papers to examine the changes in the contribution of echinoderm species richness to the macrobenthos in the shelf seas of China since the 1980s. The relative species richness (RSR) was considered as the metric to evaluate these changes. Trends analysis revealed significant declines in RSR in the shelf seas of China, the Yellow Sea, and the East China Sea from 1997 to 2009. Compared with the RSR before 1997, no significant changes in mean RSR were found after 1997, except in the Bohai Sea. In addition, relative change in the RSR of echinoderms and species richness of macrobenthos led to more changes (decrease or increase) in their respective biomasses. Our results imply that changes in species richness may alter the macrobenthic productivity of the marine benthic ecosystem.

      PubDate: 2015-08-15T05:00:29Z
  • Multidecadal changes in moisture condition during climatic growing period
           of crops in Northeast China
    • Abstract: Publication date: Available online 5 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Junfang Zhao, Jianping Guo
      Investigating the spatiotemporal dynamics of agricultural water status during crop growth season can provide scientific evidences for more efficient use of water resources and sustainable development of agricultural production under climate change. In this study, the following were used to evaluate the multidecadal changes in moisture condition during climatic growth period of crops in Northeast China from 1961 to 2010: (1) the daily climate variables gathered from 101 meteorological stations in Northeast China for 1961-2010; (2) FAO (Food and Agriculture Organization) Penman-Monteith equation; (3) 80% guaranteed probability for agro-climatic indicators; and (4) the daily average temperature stably passing 0°C, which is the threshold temperature of climatic growth period for crops. Reference crop evapotranspiration (ET0) and relative moisture index were further calculated. The results showed that Northeast China’s climate in the main agricultural areas over the past 50 years was warmer and drier in general, with a growing range and intensity of drought. From 1961 to 2010, when the daily average temperature stably passed 0°C, the average annual total precipitation (P) and ET0 with 80% guaranteed probability in Northeast China both emerged as decreasing trends with averages of 555.0mm and 993.7mm, respectively. However, the decline in P was greater than that of annual total ET0. As a result, the annual relative moisture indices sharply decreased with an average of -0.44, mostly fluctuating from -0.59 to -0.25. As far as spatial distributions were concerned, the inter-regional reductions in P and relative moisture index over the past 50 years were conspicuous, especially in some agricultural areas of central Heilongjiang Province, northeastern Jilin Province and northeastern Liaoning Province. On the contrary, ET0 obviously increased in some agricultural areas of central and northwestern Heilongjiang Province (eg. Qiqiha’er, Shuangyashan, Hegang, Suihua, etc.), and northeastern Jilin Province (eg. Baicheng). This indicated that drought existed and was unfavorable for crop growth and development, especially during the period of 2001-2010. This finding revealed that drought was still one of the most important agricultural meteorological disasters in Northeast China. Some countermeasures should be formulated to adapt to climate change. Our findings have important implications for improving climate change impact studies, for breeding scientists to breed higher yielding cultivars, and for agricultural production to cope with ongoing climate change.

      PubDate: 2015-08-06T04:03:47Z
  • Effects of adjusting cropping systems on utilization efficiency of
           climatic resources in Northeast China under future climate scenarios
    • Abstract: Publication date: Available online 5 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jianping Guo, Junfang Zhao, Yanhong Xu, Zheng Chu, Jia Mu, Qian Zhao
      Quantitatively evaluating the effects of adjusting cropping systems on the utilization efficiency of climatic resources under climate change is an important task for assessing food security in China. To understand these effects, we used daily climate variables obtained from the regional climate model RegCM3 from 1981 to 2100 under the A1B scenario and crop observations from 53 agro-meteorological experimental stations from 1981 to 2010 in Northeast China. Three one-grade zones of cropping systems were divided by heat, water, topography and crop-type, including the semi-arid areas of the northeast and northwest (III), the one crop area of warm-cool plants in semi-humid plain or hilly regions of the northeast (IV), and the two crop area in irrigated farmland in the Huanghuaihai Plain (VI). An agro-ecological zone model was used to calculate climatic potential productivities. The effects of adjusting cropping systems on climate resource utilization in Northeast China under the A1B scenario were assessed. The results indicated that from 1981 to 2100 in the III, IV and VI areas, the planting boundaries of different cropping systems in Northeast China obviously shifted toward the north and the east based on comprehensively considering the heat and precipitation resources. However, due to high temperature stress, the climatic potential productivity of spring maize was reduced in the future. Therefore, adjusting the cropping system is an effective way to improve the climatic potential productivity and climate resource utilization. Replacing the one crop in one year model (spring maize) by the two crops in one year model (winter wheat and summer maize) significantly increased the total climatic potential productivity and average utilization efficiencies. During the periods of 2011-2040, 2041-2070 and 2071-2100, the average total climatic potential productivities of winter wheat and summer maize increased by 9.36%, 11.88% and 12.13% compared to that of spring maize, respectively. Additionally, compared with spring maize, the average utilization efficiencies of thermal resources of winter wheat and summer maize dramatically increased by 9.2%, 12.1% and 12.0%, respectively. The increases in the average utilization efficiencies of precipitation resources of winter wheat and summer maize were 1.78 kg·hm-2·mm-1, 2.07 kg·hm-2·mm-1 and 1.92 kg·hm-2·mm-1 during 2011-2040, 2041- 2070 and 2071 - 2100, respectively. Our findings highlight that adjusting cropping systems can dominantly contribute to utilization efficiency increases of agricultural climatic resources in Northeast China in the future.

      PubDate: 2015-08-06T04:03:47Z
  • Evaluation of ecosystem services: a case study in the middle reach of the
           Heihe River Basin, Northwest China
    • Abstract: Publication date: Available online 4 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hongji Li, Zhihui Li, Zhaohua Li, Jing Yu, Bing Liu
      Ecosystem services evaluation aims at understanding the status of ecosystem services on different spatial and temporal scale. In this paper, we selected the middle reach of the Heihe River Basin (HRB), which is the second largest inland river basin in China, as one of the typical area to estimate the ecosystem services values (ESVs) corresponding to the land use changes. Based on the land use data and ecosystem service value coefficients, the total ecosystem services values (TESVs) of the middle reach of the HBR are quantitatively calculated, which were 9.244×108, 9.099×108, 9.131×108 and 9.146×108 USD in 1988, 2000, 2005 and 2008 respectively. During 1988-2008, the decrease of grassland, forest land, water area and unused land contributed 148.94%, 57.85%, 87.87% and 16.42% respectively to the net loss of TESVs, while the dramatic increase of cultivated land improved the TESVs with contribution of -211.08% to the net loss of TESVs. Expansion of cultivated land, which especially caused the loss of grassland and forest land, directly exerted negative impacts on the provision of ecosystem services in the study area. The findings of this research indicated that land use change was an important form of human activities, which had a strong impact on ecosystem services.

      PubDate: 2015-08-06T04:03:47Z
  • Microwave remote sensing of flood inundation
    • Abstract: Publication date: Available online 4 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Guy J-P. Schumann, Delwyn K. Moller
      Flooding is one of the most costly natural disasters and thus mapping, modelling and forecasting flood events at various temporal and spatial scales is important for any flood risk mitigation plan, disaster relief services and the global (re-)insurance markets. Both computer models and observations (ground-based, airborne and Earth-orbiting) of flood processes and variables are of great value but the amount and quality of information available varies greatly with location, spatial scales and time. It is very well known that remote sensing of flooding, especially in the microwave region of the electromagnetic spectrum, can complement ground-based observations and be integrated with flood models to augment the amount of information available to end-users, decision-makers and scientists. This paper aims to provide a concise review of both the science and applications of microwave remote sensing of flood inundation, focusing mainly on synthetic aperture radar (SAR), in a variety of natural and man-made environments. Strengths and limitations are discussed and the paper will conclude with a brief account on perspectives and emerging technologies.

      PubDate: 2015-08-06T04:03:47Z
  • Modeling the climatic effects of the land use/cover change in eastern
    • Abstract: Publication date: Available online 5 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mingna Wang, Zhe Xiong, Xiaodong Yan
      This study aims to quantify the contribution of land use/cover change (LUCC) during the last three decades to climate change conditions in eastern China. The effects of farmland expansion in Northeast China, grassland degradation in Northwest China, and deforestation in South China were simulated using the Weather Research and Forecasting (WRF) model in addition to the latest actual land cover datasets. The simulated results show that when forestland is converted to farmland, the air temperature decreased owing to an increase in surface albedo in Northeast China. The climatic effect of grassland degradation on the Loess Plateau was insignificant because of the negligible difference in albedo between grassland and cropland. In South China, deforestation generally led to a decrease in temperature. Furthermore, the temperature decrease caused by the increase in albedo counteracted the warming effects of the evapotranspiration decrease, so the summer temperature change was not significant in South China. Excluding the effects of urbanization in the North China Plain, the LUCC effects across the entire region of East China presented an overall cooling trend. However, the variation in temperature scale and magnitude was less in summer than that in winter. This result is due mainly to the cooling caused by the increase in albedo offset partly by the increase in temperature caused by the decrease in evaporation in summer. Summer precipitation showed a trend of increasing–decreasing–increasing from southeast to northwest after LUCC, which was induced mainly by the decrease in surface roughness and cyclone circulations appearing northwest of Northeast China, in the middle of the Loess Plateau, and in Yunnan province at 700 hPa after forests were converted into farmland. All results will be instructive for understanding the influence of LUCC on regional climate and future land planning in practice.

      PubDate: 2015-08-06T04:03:47Z
  • Shifts in vegetation growth in response to multiple factors on the
           Mongolian Plateau from 1982 to 2011
    • Abstract: Publication date: Available online 5 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lijuan Miao, Qiang Liu, Richard Fraser, Bin He, Xuefeng Cui
      The Mongolian Plateau (MP) steppe is one of the largest steppe environments in the world. To monitor the terrestrial vegetation dynamics on the MP and to ascertain what the driving forces, this study examined the vegetation dynamics in Republic of Mongolia (M) and the Inner Mongolia Autonomous Region (IM) of China from the period 1982 to 2011, based on the satellite-derived GIMMS NDVI3g (Normalized Difference Vegetation Index) data across three biomes (desert, grassland and forest). The results are as followed: (1) Vegetation coverage in IM was generally greater than that in M. Before 2002, time series of NDVI over the MP increased at an average rate of 0.05% yr-1. Additionally, after 2002, the NDVI increased at a rate of 0.21% yr-1. From 1982 to 2011, the area of IM and M with positive anomalies in the NDVI increased at a separate rate of 1.82% yr-1 and 1.76% yr-1, respectively. (2) At the biome scale, the inter-annual forest NDVI variation in IM and desert NDVI for the entire MP had a significant increasing trend (0.06% yr-1 and 0.04% yr-1, respectively). (3) Climate forcing was a dominant controlling factor affecting the vegetation, and the anthropogenic behavior exhibited no significant value in the whole region. However, overgrazing was the most important reason for the regional degradation, particularly in IM. (4) In the future, the forest biome will go to recovery, whereas both the grassland and desert biomes are predicted to degrade continuously.

      PubDate: 2015-08-06T04:03:47Z
  • Multiresolution wavelets and Natural time analysis before the
           January-February 2014 Cephalonia (Mw6.1 &amp; 6.0) sequence of strong
           earthquake events
    • Abstract: Publication date: Available online 30 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Filippos Vallianatos, Georgios Michas, George Hloupis
      On January 26 and February 3, 2014, Cephalonia Island(Ionian Sea, Greece) was struck by two strong, shallow earthquakes (moment magnitudes Mw6.1 and Mw6.0, respectively) that ruptured two sub-parallel, strike-slip faults, with right-lateral kinematics. The scope of the present work is to investigate the complex correlations of the earthquake activity that preceded the Mw6.1 event in the broader area of the Cephalonia Island and identify possible indications of critical stages in the evolution of the earthquake generation process. We apply the recently introduced methods of Multiresolution Wavelet Analysis (MRWA) and Natural Time (NT) analysis and for the first time we combine their results in a joint approach that may lead to universal principles in describing the evolution of the earthquake activity as it approaches a major event. In particular, the initial application of MRWA on the inter-event time series indicates a time marker 12 days prior to the major event. By using this time as the initiation point of the NT analysis, the critical stage of seismicity, where the κ1parameter reaches the critical value of κ1=0.070, is approached few days before the occurrence of the Mw6.1 earthquake.

      PubDate: 2015-08-02T03:30:17Z
  • Temperature and heat wave trends in northwest mexico
    • Abstract: Publication date: Available online 26 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Polioptro F. Martínez-Austria, Erick R. Bandala, Carlos Patiño-Gómez
      Increase in temperature extremes is one of the main expected impacts of climate change, as well as one of the first signs of its occurrence. Nevertheless, results emerging from General Circulation Models, while sufficient for large scales, are not enough for forecasting local trends and, hence, the IPCC has called for local studies based on on-site data. Indeed, it is expected that climate extremes will be detected much earlier than changes in climate averages. Heat waves are among the most important and least studied climate extremes, however its occurrence has been only barely studied and even its very definition remains controversial. This paper discusses the observed changes in temperature trends and heat waves in Northwestern Mexico, one of the most vulnerable regions of the country. The climate records in two locations of the region are analyzed, including one of the cities with extreme climate in Mexico, Mexicali City in the state of Baja California and the Yaqui River basin at Sonora State using three different methodologies. Results showed clear trends on temperature increase and occurrence of heat waves in both of the study zones using the three methodologies proposed. As result, some policy making suggestion are included in order to increase the adaptability of the studied regions to climate change, particularly related with heat wave occurrence.

      PubDate: 2015-07-28T20:54:02Z
  • Regionalisation of precipitation for the iberian peninsula and climate
    • Abstract: Publication date: Available online 26 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A.C. Parracho, P. Melo-Gonçalves, A. Rocha
      Temporal variability of precipitation over the Iberian Peninsula (IP) has high spatial gradients. Therefore, statistics of the temporal behaviour of precipitation and derived quantities over the IP must be estimated taking into account these spatial gradients. Some statistics can be displayed over a map. However there are statistics, such as Probability Density Functions at each location of the IP, that are impossible to display in a map. Because of this, it is mandatory to reduce the number of degrees of freedom which, in this case, consists of a reduction of the time series representative of the IP domain. In this work, we present a spatial partition of the IP region into areas of similar precipitation. For that, an observed dataset of daily-total precipitation for the years between 1951 and 2003 was used. The land-only high resolution data was obtained on a regular grid with 0.2° resolution in the IP domain. This data was subjected to a K-means Cluster Analysis in order to divide the IP into K regions. The clustering was performed using the squared Euclidean distance. Four clusters of IP grid points, defining 4 IP regions, were identified. The grid points in each region share the same time-varying behaviour which is different from region to region. The annual precipitation discriminates the following regions: (i) northwest Iberia, (ii) north Iberia, (iii) a large region ranging from the centre to the western and southwestern shores of the Iberia, and (iv) another large region extending from the centre to the Mediterranean shores of the IP. The regions obtained for the four seasons of the year are similar. These results are consistent with the thermodynamic characteristics described in the available literature. These Iberian regions were used to assess climate change of seasonal precipitation from the multi-model ensemble of the fifteen simulations provided by the European project ENSEMBLES. Probability Density Functions of seasonal-total precipitation averaged in each region were estimated for a reference climate (1961-1960), a near-future climate (2021-2050), and a distant-future climate (2069-2098). Climate change projections are based on comparisons of these functions between each future climate and the reference climate. Finally we emphasize that: (i) the methodology used here, based on Cluster Analysis, can be used to regionalise other areas of the world, and (ii) the identified regions of the IP can be used to represent the Iberian precipitation by four time series that can be subjected to further analysis, and whose results can be presented in a concise manner.

      PubDate: 2015-07-28T20:54:02Z
  • Estimation of Snow Density Using Full-Polarimetric Synthetic Aperture
           Radar (SAR) Data
    • Abstract: Publication date: Available online 16 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Surendar, A. Bhattacharya, G. Singh, G. Venkataraman
      In this paper, a new snow density estimation methodology is proposed for full-polarimetric Synthetic Aperture Radar (SAR) data. The generalized four component polarimetric decomposition with unitary transformation (G4U) based generalized volume parameter is utilized to invert snowpack dielectric constant using the Fresnel transmission coefficients. The snow density is then estimated using an empirical relationship. Six Radarsat-2 fine resolution full-polarimetric C-band datasets were acquired over Himachal Pradesh, India. The near-real time in-situ measurements were collected with the satellite pass to validate the proposed method. The mean absolute error (MAE) of the proposed method is 0.027 gcm-3 and the root mean square error (RMSE) is 0.032 gcm-3. The snow density variation within a season were also analyzed using multi-temporal Radarsat-2 data.

      PubDate: 2015-07-16T21:35:44Z
  • Slope angle and aspect as influencing factors on the accuracy of the SRTM
           and the ASTER GDEM databases
    • Abstract: Publication date: Available online 2 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Gergely Szabó , Sudhir Kumar Singh , Szilárd Szabó
      Presently, the application of digital elevation or surface models have increasing relevance in all areas of scientific research and in practical engineering applications. The ASTER GDEM and SRTM databases are the most widely used digital surface models, due to their free accessibility and global coverage. The SRTM model was produced using a radar-based technique and the ASTER GDEM was developed using optical stereo image-pairs. Therefore, as all models contain errors (i.e. differences stemming from real surface or vertical biases), errors in these models will also differ. Our aim was to examine these vertical biases and to calculate the rate of error variance. A TIN (Triangulated Irregular Network) model was used as a reference surface, derived from the contour lines of a large scale topographic map. Errors were evaluated with statistical and geoinformation techniques. We discovered significant differences between the surfaces. The mean difference between topographic elevations minus the SRTM-V2 is +2.6±4 meters, while the mean difference between topographic elevations minus the SRTM-V3 is +2.7±2.5 meters. With the GDEM, the mean difference was 2.7±9.1 meters. Furthermore, we found that in the case of SRTM, the differences were significant considering the aspects and the steepness of the slopes: southern and eastern directions and larger slope angles showed greater differences compared to the reference data. ‘The GDEM V2 DEM had a larger error variance, but the error did not vary significantly with slope angle.

      PubDate: 2015-07-05T15:35:20Z
  • Evaluation of SMOS soil moisture retrievals over the central United States
           for hydro-meteorological application
    • Abstract: Publication date: Available online 2 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lu Zhuo , Qiang Dai , Dawei Han
      Soil moisture has been widely recognized as a key variable in hydro-meteorological processes and plays an important role in hydrological modelling. Remote sensing techniques have improved the availability of soil moisture data, however, most previous studies have only focused on the evaluation of retrieved data against point-based observations using only one overpass (i.e., the ascending orbit). Recently, the global Level-3 soil moisture dataset generated from Soil Moisture and Ocean Salinity (SMOS) observations was released by the Barcelona Expert Center. To address the aforementioned issues, this study is particularly focused on a basin scale evaluation in which the soil moisture deficit is derived from a three-layer Xinanjiang model used as a hydrological benchmark for all comparisons. In addition, both ascending and descending overpasses were analyzed for a more comprehensive comparison. It was interesting to find that the SMOS soil moisture accuracy did not improve with time as we would have expected. Furthermore, none of the overpasses provided reliable soil moisture estimates during the frozen season, especially for the ascending orbit. When frozen periods were removed, both overpasses showed significant improvements (i.e., the correlations increased from r =−0.53 to r =−0.65 and from r =−0.62 to r =−0.70 for the ascending and descending overpasses, respectively). In addition, it was noted that the SMOS retrievals from the descending overpass consistently were approximately 11.7% wetter than the ascending retrievals by volume. The overall assessment demonstrated that the descending orbit outperformed the ascending orbit, which was unexpected and enriched our knowledge in this area. Finally, the potential reasons were discussed.

      PubDate: 2015-07-05T15:35:20Z
  • Long-term SMOS soil moisture products: A comprehensive evaluation across
           scales and methods in the Duero Basin (Spain)
    • Abstract: Publication date: Available online 4 June 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ángel González-Zamora , Nilda Sánchez , José Martínez-Fernández , Ángela Gumuzzio , María Piles , Estrella Olmedo
      The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) Level 2 soil moisture and the new L3 product from the Barcelona Expert Center (BEC) were validated from January 2010 to June 2014 using two in situ networks in Spain. The first network is the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS), which has been extensively used for validating remotely sensed observations of soil moisture. REMEDHUS can be considered a small-scale network that covers a 1300km2 region. The second network is a large-scale network that covers the main part of the Duero Basin (65,000km2). At an existing meteorological network in the Castilla y Leon region (Inforiego), soil moisture probes were installed in 2012 to provide data until 2014. Comparisons of the temporal series using different strategies (total average, land use, and soil type) as well as using the collocated data at each location were performed. Additionally, spatial correlations on each date were computed for specific days. Finally, an improved version of the Triple Collocation (TC) method, i.e., the Extended Triple Collocation (ETC), was used to compare satellite and in situ soil moisture estimates with outputs of the Soil Water Balance Model Green-Ampt (SWBM-GA). The results of this work showed that SMOS estimates were consistent with in situ measurements in the time series comparisons, with Pearson correlation coefficients (R) and an Agreement Index (AI) higher than 0.8 for the total average and the land-use averages and higher than 0.85 for the soil-texture averages. The results obtained at the Inforiego network showed slightly better results than REMEDHUS, which may be related to the larger scale of the former network. Moreover, the best results were obtained when all networks were jointly considered. In contrast, the spatial matching produced worse results for all the cases studied. These results showed that the recent reprocessing of the L2 products (v5.51) improved the accuracy of soil moisture retrievals such that they are now suitable for developing new L3 products, such as the presented in this work. Additionally, the validation based on comparisons between dense/sparse networks and satellite retrievals at a coarse resolution showed that temporal patterns in the soil moisture are better reproduced than spatial patterns.

      PubDate: 2015-06-26T14:37:28Z
  • The contribution of tropical cyclones to rainfall in Mexico
    • Abstract: Publication date: Available online 4 June 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J. Agustín Breña-Naranjo , Adrián Pedrozo-Acuña , Oscar Pozos-Estrada , Salma A. Jiménez-López , Marco R. López-López
      Investigating the contribution of tropical cyclones to the terrestrial water cycle can help quantify the benefits and hazards caused by the rainfall generated from this type of hydro-meteorological event. Rainfall induced by tropical cyclones can enhance both flood risk and groundwater recharge, and it is therefore important to characterise its minimum, mean and maximum contributions to a region or country’s water balance. This work evaluates the rainfall contribution of tropical depressions, storms and hurricanes across Mexico from 1998 to 2013 using the satellite-derived precipitation dataset TMPA 3B42. Additionally, the sensitivity of rainfall to other datasets was assessed: the national rain gauge observation network, real-time satellite rainfall and a merged product that combines rain gauges with non-calibrated space-borne rainfall measurements. The lower Baja California peninsula had the highest contribution from cyclonic rainfall in relative terms (∼40% of its total annual rainfall), whereas the contributions in the rest of the country showed a low-to-medium dependence on tropical cyclones, with mean values ranging from 0% to 20%. In quantitative terms, southern regions of Mexico can receive more than 2400mm of cyclonic rainfall during years with significant TC activity. Moreover, (a) the number of tropical cyclones impacting Mexico has been significantly increasing since 1998, but cyclonic contributions in relative and quantitative terms have not been increasing, and (b) wind speed and rainfall intensity during cyclones are not highly correlated. Future work should evaluate the impacts of such contributions on surface and groundwater hydrological processes and connect the knowledge gaps between the magnitude of tropical cyclones, flood hazards, and economic losses.

      PubDate: 2015-06-26T14:37:28Z
  • Evidence of non extensivity in the evolution of seismicity along the San
           Andreas Fault, California, USA: An approach based on Tsallis statistical
    • Abstract: Publication date: Available online 7 April 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Efstathiou , A. Tzanis , F. Vallianatos
      We examine the nature of the seismogenetic system along the San Andreas Fault (SAF), California, USA, by searching for evidence of complexity and non-extensivity in the earthquake record. We use accurate, complete and homogeneous earthquake catalogues in which aftershocks are included (raw catalogues), or have been removed by a stochastic declustering procedure (declustered catalogues). On the basis of Non-Extensive Statistical Physics (NESP), which generalizes the Boltzmann–Gibbs formalism to non-equilibrating (complex) systems, we investigate whether earthquakes are generated by an extensive self-excited Poisson process or by a non-extensive complex process. We examine bivariate cumulative frequency distributions of earthquake magnitudes and interevent times and determine the size and time dependence of the respective magnitude and temporal entropic indices, which indicate the level on non-equilibrium (correlation). It is shown that the magnitude entropic index is very stable and corresponds to proxy b-values that are remarkably consistent with the b-values computed by conventional means. The temporal entropic index computed from the raw catalogues indicate moderately to highly correlated states during the aftershock sequences of large earthquakes, progressing to quasi-uncorrelated states as these die out and before the next large event. Conversely, the analysis of the declustered catalogues shows that background seismicity exhibits moderate to high correlation that varies significantly albeit smoothly with time. This indicates a persistent sub-extensive seismogenetic system. The degree of correlation is generally higher in the southern SAF segment, which is consistent with the observation of shorter return periods for large earthquakes. A plausible explanation is that because aftershock sequences are localized in space and time, their efficient removal unveils long-range background interactions which are obscured by their presence! Our results indicate complexity in the expression of background seismicity along the San Andreas Fault, with criticality being a very likely mechanism as a consequence of the persistent non-equilibrium inferred from the temporal entropic index. However, definite conclusions cannot be drawn until the earthquake record is exhaustively studied in all its forms.

      PubDate: 2015-06-26T14:37:28Z
  • Laboratory measurements on radon exposure effects on local environmental
           temperature: Implications for satellite TIR measurements
    • Abstract: Publication date: Available online 15 April 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Giovanni Martinelli , Andrzej Tomasz Solecki , Dagmara Eulalia Tchorz-Trzeciakiewicz , Magdalena Piekarz , Katarzyna Karolina Grudzinska
      Surface latent heat flux (SLHF) is proportional to the heat released by phase changes during solidification, evaporation or melting. Effects of SLHF on the earth’s surface could be measured by satellite techniques capable of measuring thermal infrared radiation (TIR). Recent studies have found a possible correlation between SLHF and earthquakes, hence satellite techniques are widely used in research into the possible link between SLHF and earthquakes. Possible fluctuations in SLHF values during seismic periods have been attributed to different causes, such as the expulsion from the ground of greenhouse gases or because of radon. In particular, ionization processes due to radon decay could lead to changes in air temperature. Laboratory experiments have been carried out to highlight the possible role of radon in the thermal environmental conditions of a laboratory-controlled atmospheric volume.

      PubDate: 2015-06-26T14:37:28Z
  • TEC variations over the Mediterranean before and during the strong
           earthquake (M=6.5) of 12th October 2013 in Crete, Greece
    • Abstract: Publication date: Available online 16 April 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.E. Contadakis , D.N. Arabelos , G. Vergos , S.D. Spatalas , M. Skordilis
      In this paper, the total electron content (TEC) data from eight global positioning system (GPS) stations of the EUREF network, provided by IONOLAB (Turkey), were analyzed using discrete Fourier analysis to investigate the TEC variations over the Mediterranean before and during the strong earthquake of 12th October 2013, which occurred west of Crete, Greece. In accordance with the results of similar analyses in the area, the main conclusions of this study are the following: (a) TEC oscillations in a broad range of frequencies occur randomly over an area of several hundred km from the earthquake and (b) high frequency oscillations (f ⩾0.0003Hz, periods T ⩽60m) may point to the location of the earthquake with questionable accuracy. The fractal characteristics of the frequency distribution may point to the locus of the earthquake with higher accuracy. We conclude that the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanism through acoustic or gravity waves could explain this phenomenology.

      PubDate: 2015-06-26T14:37:28Z
  • Patterns of significant seismic quiescence on the Mexican Pacific coast
    • Abstract: Publication date: Available online 18 April 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Muñoz-Diosdado , A.H. Rudolf-Navarro , F. Angulo-Brown , A.G. Barrera-Ferrer
      Many authors have proposed that the study of seismicity rates is an appropriate technique for evaluating how close a seismic gap may be to rupture. We designed an algorithm for identification of patterns of significant seismic quiescence by using the definition of seismic quiescence proposed by Schreider (1990). This algorithm shows the area of quiescence where an earthquake of great magnitude may probably occur. We have applied our algorithm to the earthquake catalog on the Mexican Pacific coast located between 14 and 21degrees of North latitude and 94 and 106degrees West longitude; with depths less than or equal to 60km and magnitude greater than or equal to 4.3, which occurred from January, 1965 until December, 2014. We have found significant patterns of seismic quietude before the earthquakes of Oaxaca (November 1978, Mw =7.8), Petatlán (March 1979, Mw =7.6), Michoacán (September 1985, Mw =8.0, and Mw =7.6) and Colima (October 1995, Mw =8.0). Fortunately, in this century earthquakes of great magnitude have not occurred in Mexico. However, we have identified well-defined seismic quiescences in the Guerrero seismic-gap, which are apparently correlated with the occurrence of silent earthquakes in 2002, 2006 and 2010 recently discovered by GPS technology.

      PubDate: 2015-06-26T14:37:28Z
  • WRF-chem sensitivity to vertical resolution during a saharan dust event
    • Abstract: Publication date: Available online 8 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.C. Teixeira , A.C. Carvalho , Paolo Tuccella , Gabriele Curci , A. Rocha
      The Saharan dust event that occurred between the 22nd and 30th of June 2012 influenced the atmospheric radiative properties over North Africa, the Iberian Peninsula, the Western Mediterranean basin, extending its effects to France and Southern England. This event is well documented in satellite imagery, as well as on the air quality stations over the Iberian Peninsula and the AERONET NASA network. In order to assess the effect of the model vertical resolution on the extinction coefficient fields, as a proxy to the particulate matter concentrations in the atmosphere, the WRF-Chem model was applied during this period over a mother domain with a resolution of 18km, covering Europe and North Africa. To this end five model setups differing in the number of vertical levels were tested. Model skills were evaluated by comparing the model results with CALIPSO and EARLINET LIDAR data. Results show that the model is able to simulate the higher level aerosol transport but it is susceptible to the vertical resolution used. This is due to the thickness of the transport layers which is, eventually, thinner than the vertical resolution of the model. When comparing model results to the observed vertical profiles, it becomes evident that the broad features of the extinction coefficient profile are generally reproduced in all model configurations, but finer details are captured only by the higher resolution simulations.

      PubDate: 2015-06-26T14:37:28Z
  • Radar altimetry backscattering signatures at Ka, Ku, C, and S bands over
           West Africa
    • Abstract: Publication date: Available online 14 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): F. Frappart , C. Fatras , E. Mougin , V. Marieu , A.T. Diepkilé , F. Blarel , P. Borderies
      This study presents a comprehensive comparison of radar altimetry signatures at Ka-, Ku-, C-, and S-bands using SARAL, ENVISAT and Jason-2 data over the major bioclimatic zones, soil and vegetation types encountered in West-Africa, with an emphasis on the new information at Ka-band provided by the recently launched SARAL–Altika mission. Spatio-temporal variations of the radar altimetry responses were related to changes in surface roughness, land cover and soil wetness. Analysis of time series of backscattering coefficients along the West African bioclimatic gradient shows that radar echoes at nadir incidence are well correlated to soil moisture in semi-arid savannah environments. Radar altimeters are able to detect the presence of water even under a dense canopy cover at all frequencies. But only measurements at Ka-band are able to penetrate underneath the canopy of non-inundated tropical evergreen forests.

      PubDate: 2015-06-26T14:37:28Z
  • Parametric exponentially correlated surface emission model for L-band
           passive microwave soil moisture retrieval
    • Abstract: Publication date: Available online 15 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tianjie Zhao , Jiancheng Shi , Rajat Bindlish , Thomas Jackson , Michael Cosh , Lingmei Jiang , Zhongjun Zhang , Huimin Lan
      Surface soil moisture is an important parameter in hydrology and climate investigations. Current and future satellite missions with L-band passive microwave radiometers can provide valuable information for monitoring the global soil moisture. A factor that can play a significant role in the modeling and inversion of microwave emission from land surfaces is the surface roughness. In this study, an L-band parametric emission model for exponentially correlated surfaces was developed and implemented in a soil moisture retrieval algorithm. The approach was based on the parameterization of an effective roughness parameter of Hp in relation with the geometric roughness variables (root mean square height s and correlation length l) and incidence angle. The parameterization was developed based on a large set of simulations using an analytical approach incorporated in the advanced integral equation model (AIEM) over a wide range of geophysical properties. It was found that the effective roughness parameter decreases as surface roughness increases, but increases as incidence angle increases. In contrast to previous research, Hp was found to be expressed as a function of a defined slope parameter m = s 2/l, and coefficients of the function could be well described by a quadratic equation. The parametric model was then tested with L-band satellite data in soil moisture retrieval algorithm over the Little Washita watershed, which resulted in an unbiased root mean square error of about 0.03m3/m3 and 0.04m3/m3 for ascending and descending orbits, respectively.

      PubDate: 2015-06-26T14:37:28Z
  • Various remote sensing approaches to understanding roughness in the
           marginal ice zone
    • Abstract: Publication date: Available online 15 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mukesh Gupta
      Multi-platform based measurement approaches to understanding complex marginal ice zone (MIZ) are suggested in this paper. Physical roughness measurements using ship- and helicopter-based laser systems combined with ship-based active microwave backscattering (C-band polarimetric coherences) and dual-polarized passive microwave emission (polarization ratio, PR and spectral gradient ratios, GR at 37 and 89GHz) are presented to study diverse sea ice types found in the MIZ. Autocorrelation functions are investigated for different sea ice roughness types. Small-scale roughness classes were discriminated using data from a ship-based laser profiler. The polarimetric coherence parameter ρ HHVH , is not found to exhibit any observable sensitivity to the surface roughness for all incidence angles. Rubble-ridges, pancake ice, snow-covered frost flowers, and dense frost flowers exhibit separable signatures using GR-H and GR-V at >70° incidence angles. This paper diagnosed changes in sea ice roughness on a spatial scale of ∼0.1–4000m and on a temporal scale of ∼1–240days (ice freeze-up to summer melt). The coupling of MIZ wave roughness and aerodynamic roughness in conjunction with microwave emission and backscattering are future avenues of research. Additionally, the integration of various datasets into thermodynamic evolution model of sea ice will open pathways to successful development of inversion models of MIZ behavior.

      PubDate: 2015-06-26T14:37:28Z
  • Study on the association of green house gas (CO2) with monsoon rainfall
           using AIRS and TRMM satellite observations
    • Abstract: Publication date: Available online 16 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): R.B. Singh , M. Janmaijaya , S.K. Dhaka , V. Kumar
      Monsoon water cycle is the lifeline to over 60 per cent of the world’s population. Throughout history, the monsoon-related calamities of droughts and floods have determined the life pattern of people. The association of Green House Gases (GHGs) particularly Carbon dioxide (CO2) with monsoon has been greatly debated amongst the scientific community in the past. The effect of CO2 on the monsoon rainfall over the Indian–Indonesian region (8–30°N, 65°–100°E) is being investigated using satellite data. The correlation coefficient (R xy) between CO2 and monsoon is analysed. The R xy is not significantly positive over a greater part of the study region, except a few regions. The inter-annual anomalies of CO2 is identified for playing a secondary role to influencing monsoon while other phenomenon like ENSO might be exerting a much greater influence.

      PubDate: 2015-06-26T14:37:28Z
  • Seasonal drought predictability in Portugal using
           statistical–dynamical techniques
    • Abstract: Publication date: Available online 16 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A.F.S. Ribeiro , C.A.L. Pires
      Atmospheric forecasting and predictability are important to promote adaption and mitigation measures in order to minimize drought impacts. This study estimates hybrid (statistical–dynamical) long-range forecasts of the regional drought index SPI (3-months) over homogeneous regions from mainland Portugal, based on forecasts from the UKMO operational forecasting system, with lead-times up to 6months. ERA-Interim reanalysis data is used for the purpose of building a set of SPI predictors integrating recent past information prior to the forecast launching. Then, the advantage of combining predictors with both dynamical and statistical background in the prediction of drought conditions at different lags is evaluated. A two-step hybridization procedure is performed, in which both forecasted and observed 500hPa geopotential height fields are subjected to a PCA in order to use forecasted PCs and persistent PCs as predictors. A second hybridization step consists on a statistical/hybrid downscaling to the regional SPI, based on regression techniques, after the pre-selection of the statistically significant predictors. The SPI forecasts and the added value of combining dynamical and statistical methods are evaluated in cross-validation mode, using the R 2 and binary event scores. Results are obtained for the four seasons and it was found that winter is the most predictable season, and that most of the predictive power is on the large-scale fields from past observations. The hybridization improves the downscaling based on the forecasted PCs, since they provide complementary information (though modest) beyond that of persistent PCs. These findings provide clues about the predictability of the SPI, particularly in Portugal, and may contribute to the predictability of crops yields and to some guidance on users (such as farmers) decision making process.

      PubDate: 2015-06-26T14:37:28Z
  • Socioeconomic impacts of hydropower development on the
           Yibin–Chongqing section, upper reaches of the Yangtze River
    • Abstract: Publication date: Available online 18 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jing Ma , Yu Liu , Hao Wang , Deng Hua Yan , Ying Kang Lv , Zhaohui Yang
      The aim of this paper is to quantify the socioeconomic impacts of hydropower development to reflect its positive functions from multiple perspectives and dimensions. By applying the multi-regional Computable General Equilibrium (CGE) model to a case study of the Yibin–Chongqing section along the upper reaches of the Yangtze River, the analysis shows that hydropower development has outstanding benefits for the regional economy and livelihood improvement, as proved by various indicators including consumption, investment, GDP, employment, and income. Meanwhile, application of the CGE model provides an effective way to quantitatively assess the socioeconomic impact of hydropower and other clean energy development.

      PubDate: 2015-06-26T14:37:28Z
  • Geospace perturbations induced by the Earth: The state of the art and
           future trends
    • Abstract: Publication date: Available online 22 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. De Santis , G. De Franceschi , L. Spogli , L. Perrone , L. Alfonsi , E. Qamili , G. Cianchini , R. Di Giovambattista , S. Salvi , E. Filippi , F.J. Pavón-Carrasco , S. Monna , A. Piscini , R. Battiston , V. Vitale , P.G. Picozza , L. Conti , M. Parrot , J.-L. Pinçon , G. Balasis , M. Tavani , A. Argan , G. Piano , M.L. Rainone , W. Liu , D. Tao
      A systematic multi-parameter and multi-platform approach to study the slow process of earthquake preparation is fundamental to gain some insights on this complex phenomenon. In particular, an important contribution is the integrated analysis between ground geophysical data and satellite data. In this paper we review some of the more recent results and suggest the next directions of this kind of research. Our intention is not to detect a particular precursor but to understand the physics underlying the various observations and to establish a reliable physical model of the preparation phase before an impending earthquake. In this way, future investigation will search for suitable fore-patterns, which the physical model of multi-layers coupling predicts and characterizes by quasi-synchronism in time and geo-consistency in space. We also present alternative explanations for some anomalies which are not actually related to earthquakes, rather to other natural or anthropic processes.

      PubDate: 2015-06-26T14:37:28Z
  • Recursive cross-entropy downscaling model for spatially explicit future
           land uses: A case study of the Heihe River Basin
    • Abstract: Publication date: Available online 1 June 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xinxin Zhang , Tatiana Ermolieva , Juraj Balkovic , Aline Mosnier , Florian Kraxner , Junguo Liu
      Downscaling methods assist decision makers in coping with the uncertainty regarding sustainable local area developments. In particular, they allow investigating local heterogeneities regarding water, food, energy, and environment consistently with global, national, and sub-national drivers and trends. In this paper, we develop a conceptual framework that integrates a partial equilibrium Global Biosphere Management Model (GLOBIOM) with a dynamic cross-entropy downscaling model to derive spatially explicit projections of land uses at 1-km spatial resolution from 2010 to 2050 relying on aggregate land demand projections. The fusion of the two models is applied in a case study in Heihe River Basin to analyze the extent of potential cropland, grassland, and unused land transformations, which may exacerbate already extensive water consumption caused by rapid expansion of irrigated agriculture in the case study region. The outcomes are illustrated for two Shared Socioeconomic Pathway scenarios. The kappa coefficients show that the downscaling results are in agreement with the land use and land cover map of the Heihe River Basin, which indicates that the proposed approach produces realistic local land use projections. The downscaling results show that under both SSP scenarios the cropland area is expected to increase from 2010 to 2050, while the grassland area is projected to increase sharply from 2010 to 2030 and then gradually come to a standstill after 2030. The results can be used as an input for planning sustainable land and water management in the study area, and the conceptual framework provides a general approach to creating high-resolution land-use datasets.

      PubDate: 2015-06-26T14:37:28Z
  • Aspects regarding the use of the INFREP network for identifying possible
           seismic precursors
    • Abstract: Publication date: Available online 4 June 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Paul Dolea , Octavian Cristea , Paul Vladut Dascal , Iren-Adelina Moldovan , Pier Francesco Biagi
      In the last decades, one of the main research directions in identifying seismic precursors involved monitoring VLF (Very Low Frequency) and LF (Low Frequency) radio waves and analysing their propagation characteristics. Essentially this method consists of monitoring different available VLF and LF transmitters from long distance reception points. The received signal has two major components: the ground wave and the sky wave, where the sky wave propagates by reflection on the lower layers of the ionosphere. It is assumed that before and during major earthquakes, unusual changes may occur in the lower layers of the ionosphere, such as the modification of the charged particles number density and the altitude of the reflection zone. Therefore, these unusual changes in the ionosphere may generate unusual variations in the received signal level. The International Network for Frontier Research on Earthquake Precursors (INFREP) was developed starting with 2009 and consists of several dedicated VLF and LF radio receivers used for monitoring various radio transmitters located throughout Europe. The receivers’ locations were chosen so that the propagation path from these VLF/LF stations would pass over high seismicity regions while others were chosen to obtain different control paths. The monitoring receivers are capable of continuously measuring the received signal amplitude from the VLF/LF stations of interest. The recorded data is then stored and sent to an INFREP database, which is available on the Internet for scientific researchers. By processing and analysing VLF and LF data samples, collected at different reception points and at different periods of the year, one may be able to identify some distinct patterns in the envelope of the received signal level over time. Significant deviations from these patterns may have local causes such as the electromagnetic pollution at the monitoring point, regional causes like existing electrical storms over the propagation path or even global causes generated by high-intensity solar flares. As a consequence, classifying these perturbations and minimizing them (when possible) would represent an important step towards identifying significant pattern deviations caused by seismic activities. Taken into consideration some of the issues mentioned above, this paper intends to present some aspects meant to improve the overall performance of the existing INFREP network. The signal-to-noise ratio improvement of the monitoring receiver may be achieved by relocating the antenna (or even the entire monitoring system if possible) in areas with less electromagnetic pollution within the VLF and LF bands. Other solution may involve replacing the existing electric “whip” antennas with magnetic loop antennas. Regarding the measuring method, long-term averaging of the received signal to reduce the electromagnetic noise should be carefully applied. If the averaging time is too long, there is a risk that, during a seismic event, the details of the received signal envelope would be lost. Moreover, this may reduce the possibility of making correlations between the monitored stations and INFREP receivers in case of sudden ERP (Effective Radiated Power) variations of the VLF/LF stations. For the same reason, the time synchronization of the recorded data using (for instance) GPS technology is highly recommended. Other aspects related to the overall performance improvement of the INFREP network consist of monitoring other VLF/LF stations such as the Krasnodar station (south of Russia), part of the ALPHA/RSDN-20 VLF navigation system, or the 77.5kHz DCF77 time signal transmitter (near Frankfurt am Main, Germany). Moreover, the installation of a new reception point in Romania (near Cluj-Napoca) for monitoring the Vrancea area (within the Carpathians Mountains) and the Adriatic region will provide complementary scientific data within the network.

      PubDate: 2015-06-26T14:37:28Z
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