A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions a...A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.展开更多
in the latest version of the international Centre for Theoretical Physics＇ regional climate model, RegCM4, CLM was introduced as a new land surface scheme. The performance over China of RegCM4-CLM with different conv...in the latest version of the international Centre for Theoretical Physics＇ regional climate model, RegCM4, CLM was introduced as a new land surface scheme. The performance over China of RegCM4-CLM with different convection schemes is analyzed in this study, based on a series of short- term experiments.The model is driven by ERA-Interim data at a grid spacing of 25 km.The convection schemes employed are： Emanuel; Grell; Emanuel over land and Grell over ocean; Grell over land and Emanuel over ocean; and Tiedtke. The simulated mean surface air temperature and precipitation in December-February-January and June-July-August are compared against observation. In general, better performance of Emanuel is found both for temperature and precipitation, and in both seasons. Thus, the model physics of CLM and Emanuel for the land surface processes and convection, respectively, are recommended for further application of RegCM4 over the China region. The de^ciencies that remain in the model arealso outlined and discussed.展开更多
An enhancement mode p-GaN gate AlGaN/GaN HEMT is proposed and a physics based virtual source charge model with Landauer approach for electron transport has been developed using Verilog-A and simulated using Cadence Sp...An enhancement mode p-GaN gate AlGaN/GaN HEMT is proposed and a physics based virtual source charge model with Landauer approach for electron transport has been developed using Verilog-A and simulated using Cadence Spectre,in order to predict device characteristics such as threshold voltage,drain current and gate capacitance.The drain current model incorporates important physical effects such as velocity saturation,short channel effects like DIBL（drain induced barrier lowering）,channel length modulation（CLM）,and mobility degradation due to self-heating.The predicted Id–V（ds）,Id–V（gs）,and C–V characteristics show an excellent agreement with the experimental data for both drain current and capacitance which validate the model.The developed model was then utilized to design and simulate a single-pole single-throw（SPST）RF switch.展开更多
Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Mod...Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Model （DTVGM） into the Community Land Model （CLM 3.5）, replacing the TOPMODEL-based method to simulate runoff in the arid and semi-arid regions of China. The coupled model was calibrated at five gauging stations for the period 1980-2005 and validated for the period 2006-2010. Then, future runoff （2010-2100） was simulated for different Representative Concentration Pathways （RCP） emission scenarios. After that, the spatial distributions of the future runoff for these scenarios were discussed, and the multi-scale fluctuation characteristics of the future annual runoff for the RCP scenarios were explored using the Ensemble Empirical Mode Decomposition （EEMD） analysis method. Finally, the decadal variabilities of the future annual runoff for the entire study area and the five catchments in it were investigated. The results showed that the future annual runoff had slowly decreasing trends for scenarios RCP 2.6 and RCP 8.5 during the period 2010-2100, whereas it had a non-monotonic trend for the RCP 4.5 scenario, with a slow increase after the 2050s. Additionally, the future annual runoff clearly varied over a decadal time scale, indicating that it had clear divisions between dry and wet periods. The longest dry period was approximately 15 years （2040-2055） for the RCP 2.6 scenario and 25 years （2045-2070） for the RCP 4.5 scenario. However, the RCP 8.5 scenario was predicted to have a long dry period starting from 2045. Under these scenarios, the water resources situation of the study area will be extremely severe. Therefore, adaptive water management measures addressing climate change should be adopted to proactively confront the risks of water resources.展开更多
土壤温度反映土壤的热状态,对地表能量交换起重要作用,是影响土壤水热再分配的关键性因素。高寒山区水热传输复杂且特殊,准确模拟土壤温度对于研究高寒山区水循环过程有重要意义。CLM 5.0(Community Land Model 5.0)是CLM模式的最新版本...土壤温度反映土壤的热状态,对地表能量交换起重要作用,是影响土壤水热再分配的关键性因素。高寒山区水热传输复杂且特殊,准确模拟土壤温度对于研究高寒山区水循环过程有重要意义。CLM 5.0(Community Land Model 5.0)是CLM模式的最新版本,是目前国际上最先进的陆面过程模式之一。本文基于黑河流域上游9个典型观测站实测数据,对CLM 5.0的土壤温度模拟性能进行评估。结果表明:(1)CLM 5.0可以很好地模拟土壤温度在高寒山区的年内变化和年际变化,但模拟值相较实测值普遍存在低估。(2)CLM 5.0对土壤温度的模拟性能在高寒草甸略高于草地,土壤浅层优于深层。(3)CLM 5.0模拟的土壤温度在生长季和非生长季均呈现低估,且非生长季低估更明显;在冻结期和非冻结期均为低估,且冻结期低估更明显。(4)非生长季土壤温度的明显低估主要是冻结期土壤温度的明显低估引起,CLM 5.0中土壤冰的模拟偏差是主要原因。以上结论可为陆面过程模式CLM 5.0在高寒山区的应用及改进提供科学依据。展开更多
Pan evaporation,an indictor of potential evaporation,has decreased during the last several decades in many parts of the world;the trend is contrary to the expectation that the increase of actual evaporation will accom...Pan evaporation,an indictor of potential evaporation,has decreased during the last several decades in many parts of the world;the trend is contrary to the expectation that the increase of actual evaporation will accompany global warming,known as the pan evaporation paradox.What is the essential relationship between pan evaporation and actual evaporation? This is still an uncertain problem.In this paper,the trends of pan evaporation and actual evaporation are investigated using observational data and observation-constrained simulation results using NCAR Community Land Model(CLM) in Xinjiang from 1960 to 2005.Our analysis suggests that the decreasing trend of annual pan evaporation accompanies the increasing trend of annual actual evaporation,the tendencies of them both have statistical significance(at 99% level and at 95% level,respectively).We also find that there is the same turning point in precipitation,pan evaporation and actual evaporation of 1986,and either before the point or after,pan evaporation has inverse trend comparing with actual evaporation and precipitation.The above analysis indicates that pan evaporation and actual evaporation have complementary relationship.These results support the issue of evaporation paradox described by Brutsaert and Parlange(1998) and suggest that decrease of pan evaporation indicates an increase of actual evaporation in Xinjiang in the past half century.The correlation analysis shows that diurnal temperature range(DTR),wind speed,low cloud cover and precipitation are the most likely driving forces for the reduced pan evaporation and the ascending actual evaporation.展开更多
地表温度是影响陆-气之间能量和物质交换的重要地球物理变量,对调节全球气候系统能量循环起着不可或缺的作用。为探讨美国国家大气研究中心(The National Center for Atmospheric Research,NCAR)公共陆面模式(Community Land Model,CLM...地表温度是影响陆-气之间能量和物质交换的重要地球物理变量,对调节全球气候系统能量循环起着不可或缺的作用。为探讨美国国家大气研究中心(The National Center for Atmospheric Research,NCAR)公共陆面模式(Community Land Model,CLM)对地表温度的模拟能力,利用1948—2004年美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)大气强迫场和NCAR陆面模式CLM3.0、CLM3.5、CLM4.0和CLM4.5对内蒙古地区1981—2004年的地表温度进行off-line模拟,并与观测地面温度资料进行对比。结果表明:NCAR/CLM系列陆面模式模拟地表温度都能较好地再现内蒙古地表温度的时空变化特征,与台站观测有着较好的一致性,其中CLM4.5在内蒙古地区模拟能力最好,与观测的相关系数最高、平均偏差和均方根误差都最小,这主要得益于CLM4.5对粗糙度计算的改进;不同版本CLM模拟地表温度普遍较观测数值偏低,在冬季各版本CLM模拟结果与观测值之间的平均偏差达到最小,在夏季的偏差增大,尤其是在东部地区,夏季偏差3℃以上,说明对最高地表温度的模拟能力东部和中部地区明显低于西部地区;西部地区各个版本差别并不如东部和中部地区明显,这与CLM4.0和CLM4.5改进了雪模式和水文过程有关。综上,CLM4.0和CLM4.5在内蒙古地区有较好的适用性,且模拟值均低于实测地表温度,冬季偏差较小,夏季偏差增大,东部地区偏差大于中部和西部地区。展开更多
将稳定同位素作为诊断工具引入CLM(Community Land Model),并对巴西马瑙斯站在平衡年的不同水体中稳定同位素的季节变化进行了模拟和分析,旨在通过对陆面过程中稳定水同位素的模拟试验,了解陆面过程中稳定水同位素的循环过程,以补充观...将稳定同位素作为诊断工具引入CLM(Community Land Model),并对巴西马瑙斯站在平衡年的不同水体中稳定同位素的季节变化进行了模拟和分析,旨在通过对陆面过程中稳定水同位素的模拟试验,了解陆面过程中稳定水同位素的循环过程,以补充观测资料之缺乏,并最终利用稳定同位素的变化特性进行水文气象过程的预测.模拟的结果表明,降水、水汽和地表径流中的δ18O均存在显著的季节性变化,并与相应的水量存在反比关系.与IAEA/WMO监测数据相比,CLM的模拟基本上揭示了降水中δ18O的实际分布特征.另外,模拟的月降水量与月δ18O之间的降水量效应以及大气水线(MWL)均接近实际状况.这在一定程度上说明,引入稳定同位素效应的CLM的模拟是合理的.但也看到,模拟的降水中δ18O的季节差异明显小于实际值,降水中δ18O的季节变化展示了赤道地区理想的双峰型特点,但实际的分布却是单峰型.这些差异的产生可能与CLM本身的模拟能力有关,也可能与强迫资料的准确性有关.展开更多
Nowadays,there is tremendous growth in biometric authentication and cybersecurity applications.Thus,the efficient way of storing and securing personal biometric patterns is mandatory in most governmental and private s...Nowadays,there is tremendous growth in biometric authentication and cybersecurity applications.Thus,the efficient way of storing and securing personal biometric patterns is mandatory in most governmental and private sectors.Therefore,designing and implementing robust security algorithms for users’biometrics is still a hot research area to be investigated.This work presents a powerful biometric security system(BSS)to protect different biometric modalities such as faces,iris,and fingerprints.The proposed BSSmodel is based on hybridizing auto-encoder(AE)network and a chaos-based ciphering algorithm to cipher the details of the stored biometric patterns and ensures their secrecy.The employed AE network is unsupervised deep learning(DL)structure used in the proposed BSS model to extract main biometric features.These obtained features are utilized to generate two random chaos matrices.The first random chaos matrix is used to permute the pixels of biometric images.In contrast,the second random matrix is used to further cipher and confuse the resulting permuted biometric pixels using a two-dimensional(2D)chaotic logisticmap(CLM)algorithm.To assess the efficiency of the proposed BSS,(1)different standardized color and grayscale images of the examined fingerprint,faces,and iris biometrics were used(2)comprehensive security and recognition evaluation metrics were measured.The assessment results have proven the authentication and robustness superiority of the proposed BSSmodel compared to other existing BSSmodels.For example,the proposed BSS succeeds in getting a high area under the receiver operating characteristic(AROC)value that reached 99.97%and low rates of 0.00137,0.00148,and 3516 CMC,2023,vol.74,no.20.00157 for equal error rate(EER),false reject rate(FRR),and a false accept rate(FAR),respectively.展开更多
利用NCAR的公用陆面模式CLM4.0（Community Land Model 4.0），以1961～2010年普林斯顿大学的大气驱动场资料作为大气强迫场，对西南地区陆面过程变化进行了非耦合模拟试验。分析结果表明：西南地区降水呈现明显的干湿季节特征，季风期...利用NCAR的公用陆面模式CLM4.0（Community Land Model 4.0），以1961～2010年普林斯顿大学的大气驱动场资料作为大气强迫场，对西南地区陆面过程变化进行了非耦合模拟试验。分析结果表明：西南地区降水呈现明显的干湿季节特征，季风期降水量分布为东北-西南走向，以印度缅甸一带向东北方向递减；非季风期近似呈东西梯度，以两湖地区为中心向西递减。全年而言，西南地区约有16.7%的降水首先被冠层截留，到达地面后约有60.5%以渗透的形式进入土壤，另有约17.1%形成地表径流，还有少部分降水以直接蒸发的形式加湿低层大气。各水循环因子分布与降水分布密切相关，其中冠层截留、地表径流、冠层蒸发的季风期与非季风期特征差异不大，而地下排水和地表蒸发在非季风期均明显高于非季风期，渗透过程则相反。非季风期西南地区水循环的蒸发高、渗透小、地下排水量显著，这三个过程的共同作用，造成西南地区冬春季陆面水份显著流失，是引发西南春旱的可能原因之一。展开更多
基金jointly supported by the National Key Research and Development Program of China(Grant No.2016YFA0600704)the National Natural Science Foundation(Grant No.41375104)the Climate Change Specific Fund of China(Grant Nos.CCSF201626 and CCSF201509)
文摘A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.
基金supported by the National Natural Science Foundation of China[41375104]the Climate Change Specific Fund of China[CCSF201509]
文摘in the latest version of the international Centre for Theoretical Physics＇ regional climate model, RegCM4, CLM was introduced as a new land surface scheme. The performance over China of RegCM4-CLM with different convection schemes is analyzed in this study, based on a series of short- term experiments.The model is driven by ERA-Interim data at a grid spacing of 25 km.The convection schemes employed are： Emanuel; Grell; Emanuel over land and Grell over ocean; Grell over land and Emanuel over ocean; and Tiedtke. The simulated mean surface air temperature and precipitation in December-February-January and June-July-August are compared against observation. In general, better performance of Emanuel is found both for temperature and precipitation, and in both seasons. Thus, the model physics of CLM and Emanuel for the land surface processes and convection, respectively, are recommended for further application of RegCM4 over the China region. The de^ciencies that remain in the model arealso outlined and discussed.
基金TEQIP-II funded Silvaco TCADSMDP-II funded Cadence Tool in Department of Electronics and Communication Engineering,NIT Silchar for carrying out the research work
文摘An enhancement mode p-GaN gate AlGaN/GaN HEMT is proposed and a physics based virtual source charge model with Landauer approach for electron transport has been developed using Verilog-A and simulated using Cadence Spectre,in order to predict device characteristics such as threshold voltage,drain current and gate capacitance.The drain current model incorporates important physical effects such as velocity saturation,short channel effects like DIBL（drain induced barrier lowering）,channel length modulation（CLM）,and mobility degradation due to self-heating.The predicted Id–V（ds）,Id–V（gs）,and C–V characteristics show an excellent agreement with the experimental data for both drain current and capacitance which validate the model.The developed model was then utilized to design and simulate a single-pole single-throw（SPST）RF switch.
基金supported by the National Basic Research Program of China(2012CB956204)We acknowledge the modeling groups for providing the data for analysis,the Program for Climate Model Diagnosis and Intercomparison(PCMDI)the World Climate Research Programme’s(WCRP’s)Coupled Model Intercomparison Project for collecting and archiving the model output and organizing the data analysis
文摘Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Model （DTVGM） into the Community Land Model （CLM 3.5）, replacing the TOPMODEL-based method to simulate runoff in the arid and semi-arid regions of China. The coupled model was calibrated at five gauging stations for the period 1980-2005 and validated for the period 2006-2010. Then, future runoff （2010-2100） was simulated for different Representative Concentration Pathways （RCP） emission scenarios. After that, the spatial distributions of the future runoff for these scenarios were discussed, and the multi-scale fluctuation characteristics of the future annual runoff for the RCP scenarios were explored using the Ensemble Empirical Mode Decomposition （EEMD） analysis method. Finally, the decadal variabilities of the future annual runoff for the entire study area and the five catchments in it were investigated. The results showed that the future annual runoff had slowly decreasing trends for scenarios RCP 2.6 and RCP 8.5 during the period 2010-2100, whereas it had a non-monotonic trend for the RCP 4.5 scenario, with a slow increase after the 2050s. Additionally, the future annual runoff clearly varied over a decadal time scale, indicating that it had clear divisions between dry and wet periods. The longest dry period was approximately 15 years （2040-2055） for the RCP 2.6 scenario and 25 years （2045-2070） for the RCP 4.5 scenario. However, the RCP 8.5 scenario was predicted to have a long dry period starting from 2045. Under these scenarios, the water resources situation of the study area will be extremely severe. Therefore, adaptive water management measures addressing climate change should be adopted to proactively confront the risks of water resources.
基金National Natural Science Foundation of China, No.40830956 No.40775055+1 种基金 No.40828004 Knowledge Innovation Project of the Chinese Academy of Sciences,No.KZCX3-SW-229
文摘Pan evaporation,an indictor of potential evaporation,has decreased during the last several decades in many parts of the world;the trend is contrary to the expectation that the increase of actual evaporation will accompany global warming,known as the pan evaporation paradox.What is the essential relationship between pan evaporation and actual evaporation? This is still an uncertain problem.In this paper,the trends of pan evaporation and actual evaporation are investigated using observational data and observation-constrained simulation results using NCAR Community Land Model(CLM) in Xinjiang from 1960 to 2005.Our analysis suggests that the decreasing trend of annual pan evaporation accompanies the increasing trend of annual actual evaporation,the tendencies of them both have statistical significance(at 99% level and at 95% level,respectively).We also find that there is the same turning point in precipitation,pan evaporation and actual evaporation of 1986,and either before the point or after,pan evaporation has inverse trend comparing with actual evaporation and precipitation.The above analysis indicates that pan evaporation and actual evaporation have complementary relationship.These results support the issue of evaporation paradox described by Brutsaert and Parlange(1998) and suggest that decrease of pan evaporation indicates an increase of actual evaporation in Xinjiang in the past half century.The correlation analysis shows that diurnal temperature range(DTR),wind speed,low cloud cover and precipitation are the most likely driving forces for the reduced pan evaporation and the ascending actual evaporation.
文摘地表温度是影响陆-气之间能量和物质交换的重要地球物理变量,对调节全球气候系统能量循环起着不可或缺的作用。为探讨美国国家大气研究中心(The National Center for Atmospheric Research,NCAR)公共陆面模式(Community Land Model,CLM)对地表温度的模拟能力,利用1948—2004年美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)大气强迫场和NCAR陆面模式CLM3.0、CLM3.5、CLM4.0和CLM4.5对内蒙古地区1981—2004年的地表温度进行off-line模拟,并与观测地面温度资料进行对比。结果表明:NCAR/CLM系列陆面模式模拟地表温度都能较好地再现内蒙古地表温度的时空变化特征,与台站观测有着较好的一致性,其中CLM4.5在内蒙古地区模拟能力最好,与观测的相关系数最高、平均偏差和均方根误差都最小,这主要得益于CLM4.5对粗糙度计算的改进;不同版本CLM模拟地表温度普遍较观测数值偏低,在冬季各版本CLM模拟结果与观测值之间的平均偏差达到最小,在夏季的偏差增大,尤其是在东部地区,夏季偏差3℃以上,说明对最高地表温度的模拟能力东部和中部地区明显低于西部地区;西部地区各个版本差别并不如东部和中部地区明显,这与CLM4.0和CLM4.5改进了雪模式和水文过程有关。综上,CLM4.0和CLM4.5在内蒙古地区有较好的适用性,且模拟值均低于实测地表温度,冬季偏差较小,夏季偏差增大,东部地区偏差大于中部和西部地区。
文摘将稳定同位素作为诊断工具引入CLM(Community Land Model),并对巴西马瑙斯站在平衡年的不同水体中稳定同位素的季节变化进行了模拟和分析,旨在通过对陆面过程中稳定水同位素的模拟试验,了解陆面过程中稳定水同位素的循环过程,以补充观测资料之缺乏,并最终利用稳定同位素的变化特性进行水文气象过程的预测.模拟的结果表明,降水、水汽和地表径流中的δ18O均存在显著的季节性变化,并与相应的水量存在反比关系.与IAEA/WMO监测数据相比,CLM的模拟基本上揭示了降水中δ18O的实际分布特征.另外,模拟的月降水量与月δ18O之间的降水量效应以及大气水线(MWL)均接近实际状况.这在一定程度上说明,引入稳定同位素效应的CLM的模拟是合理的.但也看到,模拟的降水中δ18O的季节差异明显小于实际值,降水中δ18O的季节变化展示了赤道地区理想的双峰型特点,但实际的分布却是单峰型.这些差异的产生可能与CLM本身的模拟能力有关,也可能与强迫资料的准确性有关.
文摘Nowadays,there is tremendous growth in biometric authentication and cybersecurity applications.Thus,the efficient way of storing and securing personal biometric patterns is mandatory in most governmental and private sectors.Therefore,designing and implementing robust security algorithms for users’biometrics is still a hot research area to be investigated.This work presents a powerful biometric security system(BSS)to protect different biometric modalities such as faces,iris,and fingerprints.The proposed BSSmodel is based on hybridizing auto-encoder(AE)network and a chaos-based ciphering algorithm to cipher the details of the stored biometric patterns and ensures their secrecy.The employed AE network is unsupervised deep learning(DL)structure used in the proposed BSS model to extract main biometric features.These obtained features are utilized to generate two random chaos matrices.The first random chaos matrix is used to permute the pixels of biometric images.In contrast,the second random matrix is used to further cipher and confuse the resulting permuted biometric pixels using a two-dimensional(2D)chaotic logisticmap(CLM)algorithm.To assess the efficiency of the proposed BSS,(1)different standardized color and grayscale images of the examined fingerprint,faces,and iris biometrics were used(2)comprehensive security and recognition evaluation metrics were measured.The assessment results have proven the authentication and robustness superiority of the proposed BSSmodel compared to other existing BSSmodels.For example,the proposed BSS succeeds in getting a high area under the receiver operating characteristic(AROC)value that reached 99.97%and low rates of 0.00137,0.00148,and 3516 CMC,2023,vol.74,no.20.00157 for equal error rate(EER),false reject rate(FRR),and a false accept rate(FAR),respectively.
文摘利用NCAR的公用陆面模式CLM4.0（Community Land Model 4.0），以1961～2010年普林斯顿大学的大气驱动场资料作为大气强迫场，对西南地区陆面过程变化进行了非耦合模拟试验。分析结果表明：西南地区降水呈现明显的干湿季节特征，季风期降水量分布为东北-西南走向，以印度缅甸一带向东北方向递减；非季风期近似呈东西梯度，以两湖地区为中心向西递减。全年而言，西南地区约有16.7%的降水首先被冠层截留，到达地面后约有60.5%以渗透的形式进入土壤，另有约17.1%形成地表径流，还有少部分降水以直接蒸发的形式加湿低层大气。各水循环因子分布与降水分布密切相关，其中冠层截留、地表径流、冠层蒸发的季风期与非季风期特征差异不大，而地下排水和地表蒸发在非季风期均明显高于非季风期，渗透过程则相反。非季风期西南地区水循环的蒸发高、渗透小、地下排水量显著，这三个过程的共同作用，造成西南地区冬春季陆面水份显著流失，是引发西南春旱的可能原因之一。
