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PHYSICS (565 journals)            First | 1 2 3 4 5 6 | Last

Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
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Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 8)
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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)
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PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 12)
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Particle Physics Insights     Open Access   (Followers: 2)
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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)
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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: 2)
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  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 10)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
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Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 26)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 6)
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)
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Physics Research International     Open Access   (Followers: 1)
Physics Today     Hybrid Journal   (Followers: 35)
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: 468)
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)
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Radiological Physics and Technology     Hybrid Journal   (Followers: 1)
Reflets de la physique     Full-text available via subscription  
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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  

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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  [2800 journals]
  • 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
  • Integrating TRMM and MODIS satellite with socio-economic vulnerability for
           monitoring drought risk over a tropical region of India
    • Abstract: Publication date: Available online 19 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aradhana Yaduvanshi , Prashant K. Srivastava , A.C. Pandey
      Drought is a recurring feature of the climate, responsible for social and economic losses in India. In the present work, attempts were made to estimate the drought hazard and risk using spatial and temporal datasets of Tropical Rainfall Measuring Mission (TRMM) and Moderate Resolution Imaging Spectroradiometer (MODIS) in integration with socio-economic vulnerability. The TRMM rainfall was taken into account for trend analysis and Standardized Precipitation Index (SPI) estimation, with aim to investigate the changes in rainfall and deducing its pattern over the area. The SPI and average rainfall data derived from TRMM were interpolated to obtain the spatial and temporal pattern over the entire South Bihar of India, while the MODIS datasets were used to derive the Normalized Difference Vegetation Index (NDVI) deviation in the area. The Geographical Information System (GIS) is taken into account to integrate the drought vulnerability and hazard, in order to estimate the drought risk over entire South Bihar. The results indicated that approximately 36.90% area is facing high to very high drought risk over north-eastern and western part of South Bihar and need conservation measurements to combat this disaster.

      PubDate: 2015-06-26T14:37:28Z
  • On diurnal dependence and spatial scales of seismo-ionospheric effects in
           the E-layer
    • Abstract: Publication date: Available online 19 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): E.V. Liperovskaya , C.-V. Meister , D.H.H. Hoffmann , A.S. Silina
      In the present work, disturbances of the f b E s -frequency of the sporadic E-layer of the ionosphere are investigated in connection with earthquakes. The f b E s -frequency is proportional to the square root of the maximum ionisation density of the sporadic E-layer. In this work, it is shown that two days before a seismic shock with magnitude M > 5.5 , and during the shock, an increase of the f b E s -frequency is obtained around midnight at distances from the epicentre R < exp M + 100 km in the case that the focus of the shock was situated at depths smaller than 60km. Data obtained by the three ionospheric sounding stations “Kokubunji”, “Akita” and “Yamagawa” are analysed, which were recorded during a total time of 42years. The superimposed epoches method is applied for a few tens of earthquakes.

      PubDate: 2015-06-26T14:37:28Z
  • VLF/LF signal studies of the ionospheric response to strong seismic
           activity in the Far Eastern region combining the DEMETER and ground-based
    • Abstract: Publication date: Available online 21 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Rozhnoi , M. Solovieva , M. Parrot , M. Hayakawa , P.-F. Biagi , K. Schwingenschuh , V. Fedun
      The paper presents the results of a joint analysis of ground-based and satellite observations of very low-frequency and low-frequency (VLF/LF) signals during periods of strong seismic activity in the region of Kuril Islands and Japan in 2004–2010. Ground and satellite data was processed using a method based on the difference between the real signal in nighttime and that of a model. The results of the analysis show a good correlation between ground-based and satellite data for several cases of strong (M ⩾6.8) earthquakes.

      PubDate: 2015-06-26T14:37:28Z
  • Time–frequency analysis of VLF for seismic-ionospheric precursor
           detection: Evaluation of Zhao-Atlas-Marks and Hilbert-Huang Transforms
    • Abstract: Publication date: Available online 21 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Skeberis , Z.D. Zaharis , T.D. Xenos , S. Spatalas , D.N. Arabelos , M.E. Contadakis
      This work investigates the application of two post-processing methods of extracting spectra from VLF signals in order to detect disturbances that could be attributed to seismic-ionospheric precursory phenomena. Although precursory phenomena have been investigated in detail in past studies, a different application of time–frequency analysis methods may produce distinct patterns, which reveal disturbances in the VLF spectra received from stations that are in the propagation path over preparation zones, and also pinpoint disturbances that could be attributed to seismic-ionospheric precursors. To this purpose, three different methods of post processing are compared. These are the Wavelet Transform as a benchmark method in the form of the Continuous Wavelet Transform, a noise-assisted variant of the Hilbert-Huang Transform and the Zhao-Atlas-Marks Distribution. Comparative diagrams are presented and the advantages and weaknesses of each method are presented.

      PubDate: 2015-06-26T14:37:28Z
  • Inferring land surface parameters from the diurnal variability of
           microwave and infrared temperatures
    • Abstract: Publication date: Available online 27 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hamidreza Norouzi , Marouane Temimi , Amir AghaKouchak , Marzieh Azarderakhsh , Reza Khanbilvardi , Gerarda Shields , Kibrewossen Tesfagiorgis
      This study investigates the properties of the diurnal cycle of microwave brightness temperatures (TB), namely the phase and the amplitude, and their variability in time and space over the globe to infer information on key land surface parameters like changes in soil texture spatial distribution, soil moisture conditions, and vegetation density. The phase corresponds to the lag between Land Surface Temperature (LST) and TB diurnal cycles. The amplitude is determined as the difference between the maximum and the minimum of TB diurnal cycle. The diurnal cycle of TB was constructed using observations from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the Special Sensor Microwave/Imager (SSM/I). The latter offer a series of sensors, namely, F13, F14, and F15 that were used in this study for a higher temporal coverage and more accurate diurnal cycle determination. LST estimates, which are available every 3h from the International Satellite Cloud Climatology Project (ISCCP) database were used to build the LST diurnal cycle. ISCCP LST data is an infrared-based temperature with almost no penetration and is the representative of top skin temperature. The analyses of the diurnal cycles showed that the diurnal amplitude of TB decreases as the vegetation density increases, especially in the case of low frequencies which penetrate deeper into the canopy which makes them more sensitive to changes in vegetation density. The interannual variations of TB diurnal amplitudes were also in agreement with the seasonality of the vegetation cover. Over desert and rain forest regions where surface conditions do not vary significantly throughout the year, the changes in diurnal amplitudes were the lowest. A relationship between phase and amplitude values was established. It was found that the amplitude of TB diurnal cycle decreases when the phase lag increases. The spatial distribution of the determined diurnal properties, namely, phase and amplitude of TB, showed an agreement with lithology maps in desert areas. Lower TB amplitudes were observed over regions with loose siliceous rocks. Phase lag values between 1.5 and 3h corresponded to 83% of the class “loose siliceous rocks” in the Sahara Desert, which corroborates the potential of using the diurnal properties of TB as an indicator of land surface parameters.

      PubDate: 2015-06-26T14:37:28Z
  • Evidence for tidal triggering on the earthquakes of the Hellenic Arc,
    • Abstract: Publication date: Available online 28 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): G. Vergos , D.N. Arabelos , M.E. Contadakis
      In this paper we investigate the tidal triggering evidence on the earthquakes of the seismic area of the Hellenic Arc using the Hist(ogram)Cum(mulation) method. We analyze the series of the earthquakes occurred in the area which is confined by the longitudes 22° and 28°E and latitudes 34° and 36°N in the time period from 1964 to 2012. In this time period 16,137 shallow and of intermediate depth earthquakes with ML up to 6.0 and 1,482 deep earthquakes with ML up to 6.2 occurred. The result of the this analysis indicate that the monthly variation of the frequencies of earthquake occurrence is in accordance with the period of the tidal lunar monthly variations, and the same happens with the corresponding daily variations of the frequencies of earthquake occurrence with the diurnal luni-solar (K1) and semidiurnal solar (S2) tidal variations. These results are in favor of a tidal triggering process on earthquakes when the stress in the focal area is near the critical level.

      PubDate: 2015-06-26T14:37:28Z
  • A qualitative study of seismic-ionospheric precursor phenomena monitored
           by a very close to the epicenter VLF and LF receiver
    • Abstract: Publication date: Available online 5 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Skeberis , Z.D. Zaharis , T.D. Xenos , S. Spatalas , M.E. Contadakis
      This work investigates the occurrence of disturbances across a wide range of VLF and LF frequencies received prior to a seismic event (Mw=4), that took place on May 12th 2012, the epicenter of which was very close (14km) to the VLF/LF station. The signals analyzed were emitted from five VLF and five LF European transmitters. This seismic event produced precursory ionospheric disturbances, identified as spectral distortion, three days before its occurrence, providing a distinct pattern open to further investigation. Although the basis of the ionosphere interaction with seismic phenomena has been well documented in previous studies, the close proximity of the receiver to the seismic event provides a new perspective to this study. The monitored signals have undergone normalization and then they have been processed by means of the Hilbert-Huang Transform. Diagrams of the signals relevant to the phenomena are presented and the disturbances that are present in the raw data are accentuated through further processing.

      PubDate: 2015-06-26T14:37:28Z
  • Precursory signatures in the visibility graph analysis of seismicity: An
           application to the Kachchh (Western India) seismicity
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Luciano Telesca , Michele Lovallo , S.K. Aggarwal , P.K. Khan
      The Visibility Graph (VG) method maps time series into networks or graphs, converting dynamical properties of time series in topological properties of networks. The VG method was applied to the aftershock depleted catalogue of the Kachchh Gujarat (Western India) seismicity from 2003 to 2012, in order to identify possible precursory signatures in the pattern of the VG parameters. The k – M slope (the slope of the line fitting the relationship between the magnitude of the events and their connectivity degrees) seems to sharply increase significantly before the occurrence of the largest shocks (M ⩾4.5) of the sequence.

      PubDate: 2015-06-26T14:37:28Z
  • A temperature-dependent multi-relaxation spectroscopic dielectric model
           for thawed and frozen organic soil at 0.05–15GHz
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Valery Mironov , Igor Savin
      A dielectric model for thawed and frozen Arctic organic-rich soil (50% organic matter) has been developed. The model is based on soil dielectric measurements that were collected over ranges of gravimetric moisture from 0.03 to 0.55g/g, dry soil density from 0.72 to 0.87g/cm3, and temperature from 25 to −30°C (cooling run) in the frequency range of 0.05–15GHz. The refractive mixing dielectric model was applied with the Debye multi-relaxation equations to fit the measurements of the soil’s complex dielectric constant as a function of soil moisture and wave frequency. The spectroscopic parameters of the dielectric relaxations for the bound, transient bound, and unbound soil water components were derived and were complimented by the thermodynamic parameters to obtain a complete set of parameters for the proposed temperature-dependent multi-relaxation spectroscopic dielectric model for moist soils. To calculate the complex dielectric constant of the soil, the following input variables must be assigned: (1) density of dry soil, (2) gravimetric moisture, (3) wave frequency, and (4) temperature. The error of the dielectric model was evaluated and yielded RMSE ε ′ values of 0.348 and 0.188 for the soil dielectric constant and the loss factor, respectively. These values are on the order of the dielectric measurement error itself. The proposed dielectric model can be applied in active and passive microwave remote sensing techniques to develop algorithms for retrieving the soil moisture and the freeze/thaw state of organic-rich topsoil in the Arctic regions.

      PubDate: 2015-06-26T14:37:28Z
  • Anomalous CO2 content in the Gallicano thermo-mineral spring (Serchio
           Valley, Italy) before the 21 June 2013, Alpi Apuane earthquake (M=5.2)
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): L. Pierotti , F. Botti , V. D’Intinosante , G. Facca , F. Gherardi
      Since late 2002, a continuous automatic monitoring network is operating in Tuscany, Central Italy, to investigate the geochemical response of selected aquifers to local seismic activity. The monitoring is aimed at identifying possible earthquake geochemical precursors. The network is currently constituted by six stations, all equipped with sensors for the measurement of temperature, pH, redox potential, electrical conductivity, CO2 and CH4 dissolved concentration, that have been installed in the areas of highest seismic risk of the region. By combining geochemical data gathered from the automatic station of Gallicano (Garfagnana, Northern Tuscany), and obtained via chemical analyses of spring water samples collected during periodic field surveys in the area surrounding this station, the most significant aspects of the deep fluid circulation paths feeding the Gallicano thermo-mineral system have been investigated, and the geochemical baseline of the Gallicano spring defined. The CO2 continuous signal recorded by the Gallicano automatic station has been then processed over the period 2003–2013 in the search for anomalies possibly related to local seismic activity. A substantial anomaly in CO2 content has been observed at Gallicano in conjunction with the Alpi Apuane earthquake (M =5.2) of 21 June 2013.

      PubDate: 2015-06-26T14:37:28Z
  • Surface soil moisture retrievals from remote sensing: Current status,
           products &amp; future trends
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): George P. Petropoulos , Gareth Ireland , Brian Barrett
      Advances in Earth Observation (EO) technology, particularly over the last two decades, have shown that soil moisture content (SMC) can be measured to some degree or other by all regions of the electromagnetic spectrum, and a variety of techniques have been proposed to facilitate this purpose. In this review we provide a synthesis of the efforts made during the last 20years or so towards the estimation of surface SMC exploiting EO imagery, with a particular emphasis on retrievals from microwave sensors. Rather than replicating previous overview works, we provide a comprehensive and critical exploration of all the major approaches employed for retrieving SMC in a range of different global ecosystems. In this framework, we consider the newest techniques developed within optical and thermal infrared remote sensing, active and passive microwave domains, as well as assimilation or synergistic approaches. Future trends and prospects of EO for the accurate determination of SMC from space are subject to key challenges, some of which are identified and discussed within. It is evident from this review that there is potential for more accurate estimation of SMC exploiting EO technology, particularly so, by exploring the use of synergistic approaches between a variety of EO instruments. Given the importance of SMC in Earth’s land surface interactions and to a large range of applications, one can appreciate that its accurate estimation is critical in addressing key scientific and practical challenges in today’s world such as food security, sustainable planning and management of water resources. The launch of new, more sophisticated satellites strengthens the development of innovative research approaches and scientific inventions that will result in a range of pioneering and ground-breaking advancements in the retrievals of soil moisture from space.

      PubDate: 2015-06-26T14:37:28Z
  • A model of the generation of electromagnetic emissions detected prior to
    • Abstract: Publication date: Available online 16 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.K. Kachakhidze , N.K. Kachakhidze , T.D. Kaladze
      Recent satellite and ground-based observations prove that during the formative period of earthquakes VLF/LF and ULF electromagnetic emissions are observed in seismogenic areas. This work offers an original model of self-generated electromagnetic oscillations of local segments of the lithospheric origins of the emissions. In the paper, the seismogenic area is considered to be an oscillatory-distributed system. This model simplifies physical analyses of the nonlinear effects and qualitatively explains the mechanisms that generate very low frequency electromagnetic waves in the period prior to an earthquake.

      PubDate: 2015-06-26T14:37:28Z
  • Changes in animal activity prior to a major (M=7) earthquake in the
           Peruvian Andes
    • Abstract: Publication date: Available online 17 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rachel A. Grant , Jean Pierre Raulin , Friedemann T. Freund
      During earthquake preparation geophysical processes occur over varying temporal and spatial scales, some leaving their mark on the surface environment, on various biota, and even affecting the ionosphere. Reports on pre-seismic changes in animal behaviour have been greeted with scepticism by the scientific community due to the necessarily anecdotal nature of much of the evidence and a lack of consensus over possible causal mechanisms. Here we present records of changes in the abundance of mammals and birds obtained over a 30day period by motion-triggered cameras at the Yanachaga National Park, Peru, prior to the 2011 magnitude 7.0 Contamana earthquake. In addition we report on ionospheric perturbations derived from night-time very low frequency (VLF) phase data along a propagation paths passing over the epicentral region. Animal activity declined significantly over a 3-week period prior to the earthquake compared to periods of low seismic activity. Night-time ionospheric phase perturbations of the VLF signals above the epicentral area, fluctuating over the course of a few minutes, were observed, starting 2weeks before the earthquake. The concurrent observation of two widely different and seemingly unconnected precursory phenomena is of interest because recently, it has been proposed that the multitude of reported pre-earthquake phenomena may arise from a single underlying physical process: the stress-activation of highly mobile electronic charge carriers in the Earth’s crust and their flow to the Earth’s surface. The flow of charge carriers through the rock column constitutes an electric current, which is expected to fluctuate and thereby emit electromagnetic radiation in the ultralow frequency (ULF) regime. The arrival of the charge carriers can lead to air ionization at the ground-to-air interface and the injection of massive amounts of positive airborne ions, known to be aversive to animals.

      PubDate: 2015-06-26T14:37:28Z
  • Identification of the meta-instability stage via synergy of fault
           displacement: An experimental study based on the digital image correlation
    • Abstract: Publication date: Available online 21 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yan-Qun Zhuo , Jin Ma , Yan-Shuang Guo , Yun-Tao Ji
      In stick–slip experiments modeling the occurrence of earthquakes, the meta-instability stage (MIS) is the process that occurs between the peak differential stress and the onset of sudden stress drop. The MIS is the final stage before a fault becomes unstable. Thus, identification of the MIS can help to assess the proximity of the fault to the earthquake critical time. A series of stick–slip experiments on a simulated strike-slip fault were conducted using a biaxial servo-controlled press machine. Digital images of the sample surface were obtained via a high speed camera and processed using a digital image correlation method for analysis of the fault displacement field. Two parameters, A and S, are defined based on fault displacement. A, the normalized length of local pre-slip areas identified by the strike-slip component of fault displacement, is the ratio of the total length of the local pre-slip areas to the length of the fault within the observed areas and quantifies the growth of local unstable areas along the fault. S, the normalized entropy of fault displacement directions, is derived from Shannon entropy and quantifies the disorder of fault displacement directions along the fault. Based on the fault displacement field of three stick–slip events under different loading rates, the experimental results show the following: (1) Both A and S can be expressed as power functions of the normalized time during the non-linearity stage and the MIS. The peak curvatures of A and S represent the onsets of the distinct increase of A and the distinct reduction of S, respectively. (2) During each stick–slip event, the fault evolves into the MIS soon after the curvatures of both A and S reach their peak values, which indicates that the MIS is a synergetic process from independent to cooperative behavior among various parts of a fault and can be approximately identified via the peak curvatures of A and S. A possible application of these experimental results to field conditions is provided. However, further validation is required via additional experiments and exercises.

      PubDate: 2015-06-26T14:37:28Z
  • Glacier changes and their impacts on the discharge in the past
           half-century in Tekes watershed, Central Asia
    • Abstract: Publication date: Available online 31 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Baorong Xu , Zhixiang Lu , Shiyin Liu , Jing Li , Jiali Xie , Aihua Long , Zhenliang Yin , Songbing Zou
      The glacier is an important and stable water supply in Central Asia. Monitoring the change of glacier and understanding the impacts of glacier change on river discharge are critical to predict the downstream water availability change in future. Glacier changes were discussed and their impacts on river discharge were evaluated by hydrological modeling with a distributed hydrological model SWAT under two land use and land cover scenarios (1970 and 2007) in Tekes watershed, the most important source of water discharge to the Ili River. Compared to the glacier area of 1511km2 in 1970s it decreased by 332km2 in 2007, which resulted in the contribution the discharge from precipitation in the glacier area to the average annual discharge of the watershed changing from 9.8% in the period 1966–1975 to 7.8% in the period 2000–2008. In the month scale, with the decrease of glacier area, the distribution of the contribution of monthly discharge from precipitation in the glacier area to the total of the watershed changed from bimodal pattern to unimodal pattern. By linking a hydrological model to remote sensing image analysis and Chinese glacier inventories to determine glacier area change our approach in quantifying the impacts of glacier changes on hydrology at different scales, will provide quantitative information for stakeholders in making decisions for water resource management.

      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
  • Temporal correlation patterns in pre-seismic electromagnetic emissions
           reveal distinct complexity profiles prior to major earthquakes
    • Abstract: Publication date: Available online 7 April 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Reik V. Donner , Stelios M. Potirakis , Georgios Balasis , Konstantinos Eftaxias , Jürgen Kurths
      In the last years, continuous recordings of electromagnetic emissions from geophysical observatories have been recognized to exhibit characteristic fluctuation patterns prior to some major earthquakes. To further evaluate and quantify these findings, this work presents a detailed assessment of the time-varying correlation properties of such emissions during the preparatory phases preceding some recent earthquakes in Greece and Italy. During certain stages before the earthquakes’ occurrences, the electromagnetic variability profiles are characterized by a marked increase in the degree of organization of fluctuations, which allow developing hypotheses about the underlying physical mechanisms. Based on the preparatory phases of selected seismic events, the information provided by different statistical properties characterizing complementary aspects of the time-varying complexity based on temporal correlations is systematically assessed. The obtained results allow further insights into different pre-seismic stages based on the variability of electromagnetic emissions, which are probably associated with distinct geophysical processes.

      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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