Tracking the Moisture Sources of an Extreme Precipitation Event in Shandong, China in July 2007：A Computational Analysis          下载免费PDF全文

ZHANG Chi  LI Qi 《Acta Meteorologica Sinica》2014,28(4):634-644

This paper utilizes a modified Water Accounting Model （WAM） to track the moisture sources of an extreme precipitation event in Shandong during 18-20 July 2007. It is found that different methods in dealing with the residual of the water budget always produce different results in moisture recycling calculations. In addition, results from the backward tracking without the residual are in complete agreement with those from the forward tracking with the residual, and vice versa, implying a mathematical consistency. We thus analyze and derive the conditions under which the two tracking approaches equate with each other. We applied the backward tracking to the Shandong extreme rainfall case and obtained quantitative estimates of moisture contributions of three selected regions away from the rainfall area. The results indicate that the spatial pattern rather than numerical value of the recycling moisture is more reliable in tracking the moisture sources. The moisture of this Shandong rainfall event comes mostly from the nearby upwind area in Southwest China, which is of the terrestrial origin; while the moisture originating from the neighboring West Pacific contributes little to this event.  相似文献   

Diagnostic Study of Global Energy Cycle of the GRAPES Global Model in the Mixed Space-Time Domain          下载免费PDF全文

ZHAO Bin  ZHANG Bo 《Acta Meteorologica Sinica》2014,28(4):592-606

Some important diagnostic characteristics for a model’s physical background are reflected in the model’s energy transport, conversion, and cycle. Diagnosing the atmospheric energy cycle is a suitable way towards understanding and improving numerical models. In this study, formulations of the “Mixed Space-Time Domain”energy cycle are calculated and the roles of stationary and transient waves within the atmospheric energy cycle of the Global-Regional Assimilation and Prediction System （GRAPES） model are diagnosed and compared with the NCEP analysis data for July 2011. Contributions of the zonal-mean components of the energy cycle are investigated to explain the performance of numerical models. The results show that the GRAPES model has the capability to reproduce the main features of the global energy cycle as compared with the NCEP analysis. Zonal available potential energy （AZ） is converted into stationary eddy available potential energy （ASE） and transient eddy available potential energy （ATE）, and ASE and ATE have similar values. The nonlinear conversion between the two eddy energy terms is directed from the stationary to the transient. AZ becomes larger with increased forecast lead time, reflecting an enhancement of the meridional temperature gradient, which strengthens the zonal baroclinic processes and makes the conversion from AZ to eddy potential energy larger, especially for CAT （conversion from AZ to ATE）. The zonal kinetic energy （KZ） has a similar value to the sum of the stationary and transient eddy kinetic energy. Barotropic conversions are directed from eddy to zonal kinetic energy. The zonal conversion from AZ to KZ in GRAPES is around 1.5 times larger than in the NCEP analysis. The contributions of zonal energy cycle components show that transient eddy kinetic energy （KTE） is associated with the Southern Hemisphere subtropical jet and the conversion from KZ to KTE reduces in the upper tropopause near 30？S. The nonlinear barotropic conversion between stationary  相似文献   

建设与破坏——土地变化中的人力作用     

马亮 《国土资源导刊(湖南)》2014,(7)

正如果人力是顺应自然规律的、与天地和谐参用的,其变化的结果当是田地自然元气的培正扶持,是人类生存环境的改善与进步,像都江堰;如果反其道而行之,结果就很危险了。"沧海桑田"一词,道出了中国人对大千世界奇异变化认识的极致。诗文曲赋中关于土地变化的就多有精妙震撼之作。最经典的莫过于杜牧《阿房宫赋》中的两句:第一句是"蜀山兀,阿房出"。蜀山山势连绵围裹,百里千里不绝,极高极大。但是,因为要造"覆压三百余里,隔离天日"的阿房宫,蜀山上的树木都被砍光了,山变秃了。这是第一层变化,显尽了人的能  相似文献   

Coupled Modes of Rainfall over China and the Pacific Sea Surface Temperature in Boreal Summertime     

LI Chun  MA Hao 《大气科学进展》2011,28(5):1201-1214

In this study,monthly NCEP/NCAR reanalysis data and NOAA ERSST as well as observed precipitation data from 160 stations in China were used to investigate coupled modes affecting the rainfall over China and sea surface temperature (SST) in the Pacific during boreal summertime based on singular value decomposition (SVD) method.The SVD analysis revealed three remarkable coupled modes:rainfall over North China associated with an ENSO-like SST pattern (ENSO-NC),rainfall over the Yangtze River valley associated with SST anomalies in the western tropical Pacific (WTP-YRV),and rainfall over the Yellow River loop valley associated with tropical Pacific meridional mode-like SST pattern (TPMM-YRLV).These coupled SVD modes appear robust and closely correlated with the single field.Furthermore,the covariabilities among of the three coupled modes have different characteristics at the decadal time scale.In addition,the possible atmospheric teleconnections of the coupled rainfall and SST modes were discussed.For the ENSO-NC mode,anomalous low-pressure and high-pressure over the Asian continent induces moisture divergence over North China and reduces summer rainfall there.For the WTP-YRV mode,East Asia-Pacific teleconnection induces moisture convergence over the Yangtze River valley and enhances the summer rainfall there.The TPMM SST and the summer rainfall anomalies over the YRVL are linked by a circumglobal,wave-train-like,atmospheric teleconnection.  相似文献   

三种探空资料在各类强对流天气中的应用对比分析   总被引：6，自引：4，他引：2  

魏东  孙继松  雷蕾  杨波  时少英 《气象》2011,37(4):412-422

使用2007和2008年5-9月常规探空资料、微波辐射计和风廓线数据构建的特种探空资料以及BJ-RUC模式探空资料计算的常用热动力物理参量,比较了在冰雹、雷暴大风和短时暴雨等强天气中特种探空和常规探空的各参量之间的差异,探讨了特种探空在强对流天气判别中定量应用的可靠性,最后选取不同强对流天气个例,详细对比分析了三种探空...  相似文献   

"三伏"的气候学定义和区划   总被引：1，自引：1，他引：0  

夏江江  严中伟  周家斌 《气候与环境研究》2011,16(1):31-38

三伏由秦汉时盛行的五行学说延伸而来,主要指中原地区气候上一年中最闷热的一段时期.利用1960~2004年我国范围内432站观测的逐日最低(Tmin)、最高气温(Tmax)和湿度值构建人体舒适度指数(THI),并分三伏区、准三伏区、潜在三伏区和非三伏区辨识了我国的气候三伏特征及其在时间上的跃变,得到华北、江淮和江南3个地...  相似文献   

Structure of South Asia High in the stratosphere and influence of ENSO   总被引：2，自引：1，他引：1  

李崇银  李琳  谭言科 《热带气象学报(英文版)》2011,17(3):293-301

The structure of the South Asia High(SAH)in the stratosphere and the influence of ENSO on the SAH are systematically investigated with the long-term ECMWF reanalysis data.The results show that the SAH only exists in low levels of the stratosphere.The maximum intensity of the High is located at around 150 hPa and there is no obvious anti-cyclonic structure above 50 hPa.The axis of the SAH center tends to be northwest slanting from lower levels to higher levels.Further analyses show that the geopotential height and temperature fields of the SAH have dramatic anomalies during El Ni?o years and La Ni?a years. Corresponding to the ENSO,the SAH is weaker(stronger)at the warm(cold)phase.  相似文献   

对流层和平流层温度中ENSO信号的多种资料比较   总被引：2，自引：0，他引：2  

于超越  周天军  李博 《大气科学》2011,35(6):1020-1032

本文利用1980～1999年卫星资料Microwave Sounding Unit (MSU)和5种再分析资料(ERA40、JRA25、NCEP1、NCEP2、MERRA),分析了北半球冬季全球对流层中层和平流层低层温度变化中的ENSO信号,讨论了ENSO暖冷位相时温度异常的对称性和非对称性,并以MSU卫星资料为标准,...  相似文献   

ENSO,火山活动与大气CO2的年际变化   总被引：1，自引：0，他引：1       下载免费PDF全文

陈中笑  程军 《气候变化研究进展》2011,7(3):171-177

利用大气CO2及其δ13C的观测数据分析了不同区域大气CO2的季节和年际变化特征,并结合δ13C的变化趋势判断大气CO2变化的主要影响因素是来自陆地还是海洋.结果表明:大气CO2的年际变化主要受ENSO引起的陆地植被初级生产量而不是海洋吸收变化的影响,且La Ni(n)a对大气CO2的影响大于El Ni(n)o.火山活...  相似文献   

干湿循环下含盐量变化对遗址土剪切强度影响的试验研究     

沈云霞  谌文武  杜伟飞  匡静 《地震工程学报》2011,33(Z1)

中国西北干旱和半干旱地区集中降雨和强烈蒸发的特殊气候环境加剧了对土遗址的破坏。以掺入不同含量Na2SO4和NaCl的重塑土样为研究对象,通过室内模拟开放系统下干湿循环过程,并采用声波测试,反映含盐类遗址土在干湿循环下的劣化过程;测试多次循环后的遗址土剪切强度随含盐量的变化规律,并从盐类性质及波速两方面分析了干湿循环对遗址土剪切强度的作用机理。结果表明:在含水率一定的情况下纵波波速随干湿循环次数的增加而减小;干湿循环后的土体黏聚力随着盐分含量的增加呈下降趋势,内摩擦角则出现先增大后减小的现象;纵波波速与黏聚力随着含盐量的增长整体变化趋势有较好的相关性,与内摩擦角的相关性则表现为纵波波速的间断性和内摩擦角阶段性的契合。  相似文献