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  Subjects -> METEOROLOGY (Total: 110 journals)
Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 43)
Advances in Climate Change Research     Open Access   (Followers: 28)
Advances in Meteorology     Open Access   (Followers: 24)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 7)
Aeolian Research     Hybrid Journal   (Followers: 6)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18)
American Journal of Climate Change     Open Access   (Followers: 27)
Atmósfera     Open Access   (Followers: 3)
Atmosphere     Open Access   (Followers: 25)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 14)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 10)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 47)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 14)
Atmospheric Environment     Hybrid Journal   (Followers: 72)
Atmospheric Environment : X     Open Access   (Followers: 3)
Atmospheric Research     Hybrid Journal   (Followers: 69)
Atmospheric Science Letters     Open Access   (Followers: 36)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 31)
Bulletin of Atmospheric Science and Technology     Hybrid Journal   (Followers: 1)
Bulletin of the American Meteorological Society     Open Access   (Followers: 49)
Carbon Balance and Management     Open Access   (Followers: 4)
Change and Adaptation in Socio-Ecological Systems     Open Access   (Followers: 4)
Ciencia, Ambiente y Clima     Open Access   (Followers: 3)
Climate     Open Access   (Followers: 5)
Climate Change Economics     Hybrid Journal   (Followers: 14)
Climate Change Research Letters     Open Access   (Followers: 7)
Climate Change Responses     Open Access   (Followers: 8)
Climate Dynamics     Hybrid Journal   (Followers: 44)
Climate law     Hybrid Journal   (Followers: 7)
Climate of the Past (CP)     Open Access   (Followers: 5)
Climate of the Past Discussions (CPD)     Open Access  
Climate Policy     Hybrid Journal   (Followers: 37)
Climate Research     Hybrid Journal   (Followers: 6)
Climate Risk Management     Open Access   (Followers: 4)
Climate Services     Open Access   (Followers: 3)
Climate Summary of South Africa     Full-text available via subscription   (Followers: 2)
Climatic Change     Open Access   (Followers: 61)
Current Climate Change Reports     Hybrid Journal   (Followers: 4)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 27)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 5)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 18)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Economics of Disasters and Climate Change     Hybrid Journal   (Followers: 2)
Energy & Environment     Hybrid Journal   (Followers: 23)
Environmental and Climate Technologies     Open Access   (Followers: 4)
Environmental Dynamics and Global Climate Change     Open Access   (Followers: 6)
Frontiers in Climate     Open Access   (Followers: 2)
GeoHazards     Open Access   (Followers: 1)
Global Meteorology     Open Access   (Followers: 17)
International Journal of Atmospheric Sciences     Open Access   (Followers: 21)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climatology     Hybrid Journal   (Followers: 31)
International Journal of Environment and Climate Change     Open Access   (Followers: 3)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Journal of Agricultural Meteorology     Open Access  
Journal of Applied Meteorology and Climatology     Hybrid Journal   (Followers: 35)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 33)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 199)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 21)
Journal of Climate     Hybrid Journal   (Followers: 54)
Journal of Climate Change     Full-text available via subscription   (Followers: 2)
Journal of Climatology     Open Access   (Followers: 3)
Journal of Hydrology and Meteorology     Open Access   (Followers: 29)
Journal of Hydrometeorology     Hybrid Journal   (Followers: 11)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorological Research     Full-text available via subscription   (Followers: 1)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 14)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 79)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 6)
Journal of Weather Modification     Full-text available via subscription   (Followers: 2)
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
Mathematics of Climate and Weather Forecasting     Open Access   (Followers: 6)
Mediterranean Marine Science     Open Access   (Followers: 1)
Meteorologica     Open Access   (Followers: 2)
Meteorological Applications     Hybrid Journal   (Followers: 4)
Meteorological Monographs     Hybrid Journal  
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 3)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 26)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Modeling Earth Systems and Environment     Hybrid Journal  
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 14)
Monthly Weather Review     Hybrid Journal   (Followers: 34)
Nature Climate Change     Full-text available via subscription   (Followers: 126)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 35)
Nīvār     Open Access  
npj Climate and Atmospheric Science     Open Access   (Followers: 3)
Open Atmospheric Science Journal     Open Access   (Followers: 2)
Open Journal of Modern Hydrology     Open Access   (Followers: 6)
Revista Brasileira de Meteorologia     Open Access  
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 3)
Space Weather     Full-text available via subscription   (Followers: 24)
Studia Geophysica et Geodaetica     Hybrid Journal  
Tellus A     Open Access   (Followers: 22)
Tellus B     Open Access   (Followers: 21)
The Cryosphere (TC)     Open Access   (Followers: 5)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 4)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 27)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 12)
Tropical Cyclone Research and Review     Open Access   (Followers: 1)
Urban Climate     Hybrid Journal   (Followers: 4)
Weather     Hybrid Journal   (Followers: 19)
Weather and Climate Dynamics     Open Access  
Weather and Climate Extremes     Open Access   (Followers: 16)
Weather and Forecasting     Hybrid Journal   (Followers: 28)
Weatherwise     Hybrid Journal   (Followers: 4)
气候与环境研究     Full-text available via subscription   (Followers: 1)

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Acta Meteorologica Sinica
Journal Prestige (SJR): 0.638
Citation Impact (citeScore): 1
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0894-0525
Published by Springer-Verlag Homepage  [2626 journals]
  • Detecting Intensity Evolution of the Western North Pacific Super Typhoons
           in 2016 Using the Deviation Angle Variance Technique with FY Data
    • Abstract: Abstract This paper analyzes the complete lifecycle of super typhoons in 2016 in the western North Pacific (WNP) using the deviation angle variance technique (DAV-T). Based on the infrared images from Fengyun (FY) satellites, the DAV-T enables quantification of the axisymmetry of tropical cyclones (TCs) by using the DAV values; and thus, it helps improve the capability of TC intensity estimation. Case analyses of Super Typhoons Lionrock and Meranti were performed to explore the distribution characteristics of the DAV values at the various stages of TC evolution. The results show that the minimum DAV values (i.e., map minimum values: MMVs) gradually decreased and their locations constantly approached the circulation center with enhancement of the TC organization; however, when a ring or disk structure was formed around a TC, significant changes in MMV locations were no longer observed. Nonetheless, when large-scale non-closed deep convective cloud clusters appeared at the early stage or the dissipation stage of the typhoon, the axisymmetry of the TC was poor and the MMV locations tended to lie in the most convective region rather than in the TC circulation center. Overall, the MMVs and their locations, respectively, exhibited a strong correlation with the TC intensity and circulation center, and the correlation increased as the TCs became stronger. Combined with the China Meteorological Administration BestTrack dataset (CMA-BestTrack), statistical analysis of all research samples reveals that the correlation coefficient between the MMVs and maximum surface wind speeds (Vmax) was–0.80; the root mean square error (RMSE) of relative distance between the MMV locations and TC centers was 140.3 km; and especially, when the samples below the tropical depression (TD) intensity were removed, the RMSE of the relative distance decreased dramatically to 95.0 km. The value and location of the MMVs could be used as important indicators for estimating TC intensity and center.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8064-7
       
  • Remote Sensing of Tropical Cyclone Thermal Structure from Satellite
           Microwave Sounding Instruments: Impacts of Background Profiles on
           Retrievals
    • Abstract: Abstract A variational retrieval system often requires background atmospheric profiles and surface parameters in its minimization process. This study investigates the impacts of specific background profiles on retrievals of tropical cyclone (TC) thermal structure. In our Microwave Retrieval Testbed (MRT), the K-means clustering algorithm is utilized to generate a set of mean temperature and water vapor profiles according to stratiform and convective precipitation in hurricane conditions. The Advanced Technology Microwave Sounder (ATMS) observations are then used to select the profiles according to cloud type. It is shown that the cloud-based background profiles result in better hurricane thermal structures retrieved from ATMS observations. Compared to the Global Positioning System (GPS) dropsonde observations, the temperature and specific humidity errors in the TC inner region are less than 3 K and 2.5 g kg–1, respectively, which are significantly smaller than the retrievals without using the cloud-based profiles. Further experiments show that all the ATMS observations could retrieve well both temperature and humidity structures, especially within the inner core region. Thus, both temperature and humidity profiles derived from microwave sounding instruments in hurricane conditions can be reliably used for evaluation of the storm intensity with a high fidelity.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8094-1
       
  • Simulation and Projection of Near-Surface Wind Speeds in China by BCC-CSM
           Models
    • Abstract: Abstract We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions (BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1m on approximately 110-km resolution) in simulating the nearsurface wind speeds (NWS) in China during 1961–2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961–2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value. This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1m under different Representative Concentration Pathway (RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21st century under both the middle (RCP4.5) and high (RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8043-z
       
  • Boreal Summer Intraseasonal Oscillation in the Asian–Pacific Monsoon
           Region Simulated in CAMS-CSM
    • Abstract: Abstract The boreal summer intraseasonal oscillation (BSISO) is simulated by the Climate System Model (CSM) developed at the Chinese Academy of Meteorological Sciences (CAMS), China Meteorological Administration. Firstly, the results indicate that this new model is able to reasonably simulate the annual cycle and seasonal mean of the precipitation, as well as the vertical shear of large-scale zonal wind in the tropics. The model also reproduces the eastward and northward propagating oscillation signals similar to those found in observations. The simulation of BSISO is generally in agreement with the observations in terms of variance center, periodicity, and propagation, with the exception that the magnitude of BSISO anomalous convections are underestimated during both its eastward propagation along the equator and its northward propagation over the Asian–Pacific summer monsoon region. Our preliminary evaluation of the simulated BSISO by CAMS-CSM suggests that this new model has the capability, to a certain extent, to capture the BSISO features, including its propagation zonally along the equator and meridionally over the Asian monsoon region.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8080-7
       
  • Diurnal Variations of Summer Precipitation over the Qilian Mountains in
           Northwest China
    • Abstract: Abstract Based on the high-density hourly rain-gauge data from 265 stations over the Qilian Mountains in Northwest China, climatic mean diurnal variations of summer rainfall over different topographies of this area are investigated. Influences of the gauge elevations on the diurnal variation of rainfall are also revealed. Distinct regional features of diurnal variations in rainfall are observed over the Qilian Mountains. Rainfall over the Qinghai Lake areas shows a single nocturnal peak. A dominant, late-afternoon peak of rainfall occurs over the mountain tops. Over the northeastern and southeastern slopes, a dominant diurnal peak appears in the late afternoon, and an evident second peak is found in the early morning, respectively. The strengths of the early-morning peaks in the rainfall frequency are closely related to the rainfall events with different durations over the two slopes. The early-morning peak is dominant across plains with low elevations. From the mountain tops to the plains, the diurnal peaks of rainfall gradually vary from the dominant late-afternoon peak to the dominant early-morning peak with the enhanced early-morning peak in concurrent with the decreasing gauge elevation over the northeastern and southeastern slopes. Further examination indicates that the rainfall at higher elevations over the northeastern and southeastern slopes occurs more readily in the afternoon, compared to the lower elevations. This phenomenon corresponds to the result that the proportion of the rainfall frequency occurring during the early-morning period decreases with increasing elevations over the two slopes.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8103-4
       
  • Below-Cloud Aerosol Scavenging by Different-Intensity Rains in Beijing
           City
    • Abstract: Abstract Below-cloud aerosol scavenging process by precipitation is important for cleaning the polluted aerosols in the atmosphere, and is also a main process for acid rain formation. However, the related physical mechanism has not been well documented and clarified yet. In this paper, we investigated the below-cloud PM2.5 (particulate matter with aerodynamic diameter being 2.5 μm or less) scavenging by different-intensity rains under polluted conditions characterized by high PM2.5 concentrations, based on in-situ measurements from March 2014 to July 2016 in Beijing city. It was found that relatively more intense rainfall events were more efficient in removing the polluted aerosols in the atmosphere. The mean PM2.5 scavenging ratio and its standard deviation (SD) were 5.1% ± 25.7%, 38.5% ± 29.0%, and 50.6% ± 21.2% for light, moderate, and heavy rain events, respectively. We further found that the key impact factors on below-cloud PM2.5 scavenging ratio for light rain events were rain duration and wind speed rather than raindrop size distribution. However, the impacts of rain duration and wind speed on scavenging ratio were not important for moderate and heavy rain events. To our knowledge, this is the first statistical result about the effects of rain intensity, rain duration, and raindrop size distribution on below-cloud scavenging in China.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8079-0
       
  • Sea-Salt Aerosol Effects on the Simulated Microphysics and Precipitation
           in a Tropical Cyclone
    • Abstract: Abstract We investigate the effects of sea-salt aerosol (SSA) activated as cloud condensation nuclei on the microphysical processes, precipitation, and thermodynamics of a tropical cyclone (TC). The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) was used together with a parameterization of SSA production. Three simulations, with different levels of SSA emission (CTL, LOW, HIGH), were conducted. The simulation results show that SSA contributes to the processes of autoconversion of cloud water and accretion of cloud water by rain, thereby promoting rain formation. The latent heat release increases with SSA emission, slightly increasing horizontal wind speeds of the TC. The presence of SSA also regulates the thermodynamic structure and precipitation of the TC. In the HIGH simulation, higher latent heat release gives rise to stronger updrafts in the TC eyewall area, leading to enhanced precipitation. In the LOW simulation, due to decreased latent heat release, the temperature in the TC eye is lower, enhancing the downdrafts in the region; and because of conservation of mass, updrafts in the eyewall also strengthen slightly; as a result, precipitation in the LOW experiment is a little higher than that in the CTL experiment. Overall, the relationship between the precipitation rate and SSA emission is nonlinear.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8108-z
       
  • An Assessment of ENSO Stability in CAMS Climate System Model Simulations
    • Abstract: Abstract We present an overview of the El Niño–Southern Oscillation (ENSO) stability simulation using the Chinese Academy of Meteorological Sciences climate system model (CAMS-CSM). The ENSO stability was quantified based on the Bjerknes (BJ) stability index. Generally speaking, CAMS-CSM has the capacity of reasonably representing the BJ index and ENSO-related air–sea feedback processes. The major simulation biases exist in the underestimated thermodynamic damping and thermocline feedbacks. Further diagnostic analysis reveals that the underestimated thermodynamic feedback is due to the underestimation of the shortwave radiation feedback, which arises from the cold bias in mean sea surface temperature (SST) over central–eastern equatorial Pacific (CEEP). The underestimated thermocline feedback is attributed to the weakened mean upwelling and weakened wind–SST feedback (μa) in the model simulation compared to observation. We found that the weakened μa is also due to the cold mean SST over the CEEP. The study highlights the essential role of reasonably representing the climatological mean state in ENSO simulations.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-018-8092-8
       
  • Climate Sensitivity and Feedbacks of a New Coupled Model CAMS-CSM to
           Idealized CO 2 Forcing: A Comparison with CMIP5 Models
    • Abstract: Abstract Climate sensitivity and feedbacks are basic and important metrics to a climate system. They determine how large surface air temperature will increase under CO2 forcing ultimately, which is essential for carbon reduction policies to achieve a specific warming target. In this study, these metrics are analyzed in a climate system model newly developed by the Chinese Academy of Meteorological Sciences (CAMS-CSM) and compared with multi-model results from the Coupled Model Comparison Project phase 5 (CMIP5). Based on two idealized CO2 forcing scenarios, i.e., abruptly quadrupled CO2 and CO2 increasing 1% per year, the equilibrium climate sensitivity (ECS) and transient climate response (TCR) in CAMS-CSM are estimated to be about 2.27 and 1.88 K, respectively. The ECS is near the lower bound of CMIP5 models whereas the TCR is closer to the multi-model ensemble mean (MME) of CMIP5 due to compensation of a relatively low ocean heat uptake (OHU) efficiency. The low ECS is caused by an unusually negative climate feedback in CAMS-CSM, which is attributed to cloud shortwave feedback (λSWCL) over the tropical Indo-Pacific Ocean. The CMIP5 ensemble shows that more negative λSWCL is related to larger increase in low-level (925–700 hPa) cloud over the tropical Indo-Pacific under warming, which can explain about 90% of λSWCL in CAMS-CSM. Static stability of planetary boundary layer in the pre-industrial simulation is a critical factor controlling the low-cloud response and λSWCL across the CMIP5 models and CAMS-CSM. Evidently, weak stability in CAMS-CSM favors lowcloud formation under warming due to increased low-level convergence and relative humidity, with the help of enhanced evaporation from the warming tropical Pacific. Consequently, cloud liquid water increases, amplifying cloud albedo, and eventually contributing to the unusually negative λSWCL and low ECS in CAMS-CSM. Moreover, the OHU may influence climate feedbacks and then the ECS by modulating regional sea surface temperature responses.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8074-5
       
  • ENSO Features, Dynamics, and Teleconnections to East Asian Climate as
           Simulated in CAMS-CSM
    • Abstract: Abstract This study evaluates the performance of CAMS-CSM (the climate system model of the Chinese Academy of Meteorological Sciences) in simulating the features, dynamics, and teleconnections to East Asian climate of the El Niño–Southern Oscillation (ENSO). In general, fundamental features of ENSO, such as its dominant patterns and phase-locking features, are reproduced well. The two types of El Niño are also represented, in terms of their spatial distributions and mutual independency. However, the skewed feature is missed in the model and the simulation of ENSO is extremely strong, which is found—based on Bjerknes index assessment—to be caused by underestimation of the shortwave damping effect. Besides, the modeled ENSO exhibits a regular oscillation with a period shorter than observed. By utilizing the Wyrtki index, it is suggested that this periodicity bias results from an overly quick phase transition induced by feedback from the thermocline and zonal advection. In addition to internal dynamics of ENSO, its external precursors—such as the North Pacific Oscillation with its accompanying seasonal footprinting mechanism, and the Indian Ocean Dipole with its 1-yr lead correlation with ENSO—are reproduced well by the model. Furthermore, with respect to the impacts of ENSO on the East Asian summer monsoon, although the anomalous Philippine anticyclone is reproduced in the post-El Niño summer, it exhibits an eastward shift compared with observation; and as a consequence, the observed flooding of the Yangtze River basin is poorly represented, with unrealistic air–sea interaction over the South China Sea being the likely physical origin of this bias. The response of wintertime lowertropospheric circulation to ENSO is simulated well, in spite of an underestimation of temperature anomalies in central China. This study highlights the dynamic processes that are key for the simulation of ENSO, which could shed some light on improving this model in the future.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8101-6
       
  • Projection of Landslides in China during the 21st Century under the RCP8.5
           Scenario
    • Abstract: Abstract More and more rainstorms and other extreme weather events occur in the context of global warming, which may increase the risks of landslides. In this paper, changes of landslides in the 21st century of China under the high emission scenario RCP8.5 (Representative Concentration Pathway) are projected by using a statistical landslide forecasting model and the regional climate model RegCM4.0. The statistical landslide model is based on an improved landslide susceptibility map of China and a rainfall intensity–duration threshold. First, it is driven by observed rainfall and RegCM4.0 rainfall in 1980–99, and it can reproduce the spatial distribution of landslides in China pretty well. Then, it is used to forecast the landslide changes over China in the future under the RCP8.5 scenario. The results consistently reveal that landslides will increase significantly in most areas of China, especially in the southeastern, northeastern, and western parts of Northwest China. The change pattern at the end of the 21st century is generally consistent with that in the middle of the 21st century, but with larger increment and magnitude. In terms of the probability, the proportion of grid points that are very likely and extremely likely to experience landslides will also increase.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-018-8083-9
       
  • Role of Differences in Surface Diurnal–Nocturnal Thermodynamics over
           Complex Terrain in a Squall Line Process
    • Abstract: Abstract Squall lines frequently invade the Yangtze–Huaihe River region (YHR), where the complex terrain of rivers, lakes, and mountains plays an important role in the initiation and maintenance of convection. The surface heat flux not only varies with surface conditions, but also changes between day and night. Coupled with the terrain forcing, such diurnal–nocturnal thermodynamic differences shift the low-level baroclinity, and thus further complicate the convective activities. To investigate the integrated impact of diurnal–nocturnal thermodynamic differences on the development of squall lines over complex terrain including disasters that might ensue, numerical modeling experiments on a squall line in July 2014 were performed by forcing a squall line to pass the YHR separately at daytime and nighttime. The results show that the low-level instability during the day is much larger than that during the night, and is determined predominantly by the shortwave heating of the surface. Specifically, the solar radiation enhances the temperature gradient between the warmland ahead of the squall line and the convectively generated cold pool in the region around Chaohu Lake and the Yangtze River. Such low-level baroclinity sets preconditions in the environment towards the occurrence of deep convection. The increased precipitation and the evaporation of rain in the daytime also enhance the cold pool and the associated downdraft, which further intensify the squall line. Meanwhile, the valley breeze is intensified during the day. Such scenarios promote convection that extends the squall line and the associated heavy precipitation and wind gusts southward. This research may have significant implications for enhancing the squall line prediction capability in the YHR and improving our understanding of the physical mechanisms of convective activities over complex terrain.
      PubDate: 2019-02-01
      DOI: 10.1007/s13351-019-8052-y
       
  • Impacts of Land-Use Data on the Simulation of Surface Air Temperature in
           Northwest China
    • Abstract: Abstract This study examines the impacts of land-use data on the simulation of surface air temperature in Northwest China by the Weather Research and Forecasting (WRF) model. International Geosphere–Biosphere Program (IGBP) landuse data with 500-m spatial resolution are generated from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products. These data are used to replace the default U.S. Geological Survey (USGS) land-use data in the WRF model. Based on the data recorded by national basic meteorological observing stations in Northwest China, results are compared and evaluated. It is found that replacing the default USGS land-use data in the WRF model with the IGBP data improves the ability of the model to simulate surface air temperature in Northwest China in July and December 2015. Errors in the simulated daytime surface air temperature are reduced, while the results vary between seasons. There is some variation in the degree and range of impacts of land-use data on surface air temperature among seasons. Using the IGBP data, the simulated daytime surface air temperature in July 2015 improves at a relatively small number of stations, but to a relatively large degree; whereas the simulation of daytime surface air temperature in December 2015 improves at almost all stations, but only to a relatively small degree (within 1°C). Mitigation of daytime surface air temperature overestimation in July 2015 is influenced mainly by the change in ground heat flux. The modification of underestimated temperature comes mainly from the improvement of simulated net radiation in December 2015.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-7151-5
       
  • Arctic Climate Changes Based on Historical Simulations (1900‒2013)
           with the CAMS-CSM
    • Abstract: Abstract The Chinese Academy of Meteorological Sciences Climate System Model (CAMS-CSM) is a newly developed global climate model that will participate in the Coupled Model Intercomparison Project phase 6. Based on historical simulations (1900‒2013), we evaluate the model performance in simulating the observed characteristics of the Arctic climate system, which includes air temperature, precipitation, the Arctic Oscillation (AO), ocean temperature/salinity, the Atlantic meridional overturning circulation (AMOC), snow cover, and sea ice. The model‒data comparisons indicate that the CAMS-CSM reproduces spatial patterns of climatological mean air temperature over the Arctic (60°‒90°N) and a rapid warming trend from 1979 to 2013. However, the warming trend is overestimated south of the Arctic Circle, implying a subdued Arctic amplification. The distribution of climatological precipitation in the Arctic is broadly captured in the model, whereas it shows limited skills in depicting the overall increasing trend. The AO can be reproduced by the CAMS-CSM in terms of reasonable patterns and variability. Regarding the ocean simulation, the model underestimates the AMOC and zonally averaged ocean temperatures and salinity above a depth of 500 m, and it fails to reproduce the observed increasing trend in the upper ocean heat content in the Arctic. The large-scale distribution of the snow cover extent (SCE) in the Northern Hemisphere and the overall decreasing trend in the spring SCE are captured by the CAMS-CSM, while the biased magnitudes exist. Due to the underestimation of the AMOC and the poor quantification of air–sea interaction, the CAMS-CSM overestimates regional sea ice and underestimates the observed decreasing trend in Arctic sea–ice area in September. Overall, the CAMS-CSM reproduces a climatological distribution of the Arctic climate system and general trends from 1979 to 2013 compared with the observations, but it shows limited skills in modeling local trends and interannual variability.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-7188-5
       
  • Classification and Diurnal Variations of Precipitation Echoes Observed by
           a C-band Vertically-Pointing Radar in Central Tibetan Plateau during
           TIPEX-III 2014-IOP
    • Abstract: Abstract This study investigates classification and diurnal variations of the precipitation echoes over the central Tibetan Plateau based on the observations collected from a C-band vertically-pointing frequency-modulated continuous-wave (C-FMCW) radar during the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX-III) 2014-Intensive Observation Period (2014-IOP). The results show that 51.32% of the vertical profiles have valid echoes with reflectivity >–10 dBZ, and 35.06% of the valid echo profiles produce precipitation at the ground (precipitation profiles); stratiform precipitation with an evident bright-band signature, weak convective precipitation, and strong convective precipitation account for 52.03%, 42.98%, and 4.99% of the precipitation profiles, respectively. About 59.84% of the precipitation occurs in the afternoon to midnight, while 40.16% of the precipitation with weaker intensity is observed in the nocturnal hours and in the morning. Diurnal variation of occurrence frequency of precipitation shows a major peak during 2100–2200 LST (local solar time) with 59.02% being the stratiform precipitation; the secondary peak appears during 1300–1400 LST with 59.71% being the weak convective precipitation; the strong convective precipitation occurs mostly (81.83%) in the afternoon and evening with two peaks over 1200–1300 and 1700–1800 LST, respectively. Starting from approximately 1100 LST, precipitation echoes develop with enhanced vertical air motion, elevated echo top, and increasing radar reflectivity. Intense upward air motion occurs most frequently in 1700–1800 LST with a secondary peak in 1100–1400 LST, while the tops of precipitation echoes and intense upward air motion reach their highest levels during 1600–1800 LST. The atmospheric conditions in the early morning are disadvantageous for convective initiation and development. Around noon, the convective available potential energy (CAPE) increases markedly, convective inhibition (CIN) is generally small, and a super-dry-adiabatic layer is present near the surface (0–400 m). In the early evening, some larger values of CAPE, level of neutral buoyancy, and total precipitable water are present, suggesting more favorable thermodynamic and water vapor conditions.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8084-8
       
  • An Assessment of CAMS-CSM in Simulating Land–Atmosphere Heat and
           Water Exchanges
    • Abstract: Abstract The Chinese Academy of Meteorological Sciences (CAMS) has been devoted to developing a climate system model (CSM) to meet demand for climate simulation and prediction for the East Asian region. In this study, we evaluated the performance of CAMS-CSM in regard to sensible heat flux (H), latent heat flux (LE), surface temperature, soil moisture, and snow depth, focusing on the Atmospheric Model Intercomparison Project experiment, with the aim of participating in the Coupled Model Intercomparison Project phase 6. We systematically assessed the simulation results achieved by CAMS-CSM for these variables against various reference products and ground observations, including the FLUXNET model tree ensembles H and LE data, Climate Prediction Center soil moisture data, snow depth climatology data, and Chinese ground observations of snow depth and winter surface temperature. We compared these results with data from the ECMWF Interim reanalysis (ERA-Interim) and Global Land Data Assimilation System (GLDAS). Our results indicated that CAMS-CSM simulations were better than or comparable to ERAInterim reanalysis for snow depth and winter surface temperature at regional scales, but slightly worse when simulating total column soil moisture. The root-mean-square differences of H in CAMS-CSM were all greater than those from the ERA-Interim reanalysis, but less than or comparable to those from GLDAS. The spatial correlations for H in CAMS-CSM were the lowest in nearly all regions, except for North America. CAMS-CSM LE produced the lowest bias in Siberia, North America, and South America, but with the lowest spatial correlation coefficients. Therefore, there are still scopes for improving H and LE simulations in CAMS-CSM, particularly for LE.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8055-0
       
  • Drivers of the Severity of the Extreme Hot Summer of 2015 in Western China
    • Abstract: Abstract Western China experienced an extreme hot summer in 2015, breaking a number of temperature records. The summer mean surface air temperature (SAT) anomaly was twice the interannual variability. The hottest daytime temperature (TXx) and warmest night-time temperature (TNx) were the highest in China since 1964. This extreme hot summer occurred in the context of steadily increasing temperatures in recent decades. We carried out a set of experiments to evaluate the extent to which the changes in sea surface temperature (SST)/sea ice extent (SIE) and anthropogenic forcing drove the severity of the extreme summer of 2015 in western China. Our results indicate that about 65%–72% of the observed changes in the seasonal mean SAT and the daily maximum (Tmax) and daily minimum (Tmin) temperatures over western China resulted from changes in boundary forcings, including the SST/SIE and anthropogenic forcing. For the relative role of individual forcing, the direct impact of changes in anthropogenic forcing explain about 42% of the SAT warming and 60% (40%) of the increase in TNx and Tmin (TXx and Tmax) in the model response. The changes in SST/SIE contributed to the remaining surface warming and the increase in hot extremes, which are mainly the result of changes in the SST over the Pacific Ocean, where a super El Niño event occurred. Our study indicates a prominent role for the direct impact of anthropogenic forcing in the severity of the extreme hot summer in western China in 2015, although the changes in SST/SIE, as well as the internal variability of the atmosphere, also made a contribution.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8004-y
       
  • Conjugate Gradient Algorithm in the Four-Dimensional Variational Data
           Assimilation System in GRAPES
    • Abstract: Abstract Minimization algorithms are singular components in four-dimensional variational data assimilation (4DVar). In this paper, the convergence and application of the conjugate gradient algorithm (CGA), which is based on the Lanczos iterative algorithm and the Hessian matrix derived from tangent linear and adjoint models using a non-hydrostatic framework, are investigated in the 4DVar minimization. First, the influence of the Gram-Schmidt orthogonalization of the Lanczos vector on the convergence of the Lanczos algorithm is studied. The results show that the Lanczos algorithm without orthogonalization fails to converge after the ninth iteration in the 4DVar minimization, while the orthogonalized Lanczos algorithm converges stably. Second, the convergence and computational efficiency of the CGA and quasi-Newton method in batch cycling assimilation experiments are compared on the 4DVar platform of the Global/Regional Assimilation and Prediction System (GRAPES). The CGA is 40% more computationally efficient than the quasi-Newton method, although the equivalent analysis results can be obtained by using either the CGA or the quasi-Newton method. Thus, the CGA based on Lanczos iterations is better for solving the optimization problems in the GRAPES 4DVar system.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8053-2
       
  • The CAMS Climate System Model and a Basic Evaluation of Its Climatology
           and Climate Variability Simulation
    • Abstract: Abstract A new coupled climate system model (CSM) has been developed at the Chinese Academy of Meteorological Sciences (CAMS) by employing several state-of-the-art component models. The coupled CAMS-CSM consists of the modified atmospheric model [ECmwf-HAMburg (ECHAM5)], ocean model [Modular Ocean Model (MOM4)], sea ice model [Sea Ice Simulator (SIS)], and land surface model [Common Land Model (CoLM)]. A detailed model description is presented and both the pre-industrial and “historical” simulations are preliminarily evaluated in this study. The model can reproduce the climatological mean states and seasonal cycles of the major climate system quantities, including the sea surface temperature, precipitation, sea ice extent, and the equatorial thermocline. The major climate variability modes are also reasonably captured by the CAMS-CSM, such as the Madden–Julian Oscillation (MJO), El Niño–Southern Oscillation (ENSO), East Asian Summer Monsoon (EASM), and Pacific Decadal Oscillation (PDO). The model shows a promising ability to simulate the EASM variability and the ENSO–EASM relationship. Some biases still exist, such as the false double-intertropical convergence zone (ITCZ) in the annual mean precipitation field, the overestimated ENSO amplitude, and the weakened Bjerknes feedback associated with ENSO; and thus the CAMS-CSM needs further improvements.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8058-x
       
  • Identification Standard for ENSO Events and Its Application to Climate
           Monitoring and Prediction in China
    • Abstract: Abstract The El Niño–Southern Oscillation (ENSO) reflects anomalous variations in the sea surface temperature (SST) and atmospheric circulation over the tropical central–eastern Pacific. It remarkably impacts on weather and climate worldwide, so monitoring and prediction of ENSO draw intensive research. However, there is not yet a unique standard internationally for identifying the timing, intensity, and type of ENSO events. The National Climate Center of China Meteorological Administration (NCC/CMA) has led the effort to establish a national identification standard of ENSO events, which was officially endorsed by the National Standardization Administration of China and implemented operationally in NCC/CMA in 2017. In this paper, two key aspects of this standard are introduced. First, the Niño3.4 SST anomaly index, which is well-recognized in the international ENSO research community and used operationally in the US, has replaced the previous Niño Z index and been used to identify the start, end, and peak times, and intensity of ENSO events. Second, two new indices—the eastern Pacific ENSO (EP) index and the central Pacific ENSO (CP) index, based on the SST conditions in Niño3 and Niño4 region respectively, are calculated to first determine the ENSO type before monitoring and assessing the impacts of ENSO on China’s climate. With this standard, all historical ENSO events since 1950 are consistently re-identified; their distinct properties are diagnosed and presented; and the impacts of ENSO events under different types on China’s climate are re-assessed. This standard is also employed to validate the intensity, grade, and type of the ENSO events predicted by the NCC/CMA operational ENSO prediction system. The new standard and the thus derived unified set of re-analyzed historical ENSO events and associated information provide a good reference for better monitoring and prediction of future ENSO events.
      PubDate: 2018-12-01
      DOI: 10.1007/s13351-018-8078-6
       
 
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