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1.
P. L. S. Rao 《Pure and Applied Geophysics》2003,160(12):2447-2462
In this paper, the maintenance of Asian summer monsoon circulation is compared in the National Centres for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis and National Centre for Medium Range Weather Forecasting (NCMRWF), India operational analysis. The time mean summer monsoon circulation is bifurcated into stable mean and transient eddy components. The mean component of the summer monsoon circulation is elucidated through the study of large-scale balances of kinetic energy, heat and moisture. Although the balance requirements are fairly satisfied by both NCEP/NCAR and NCMRWF fields, a major difference is noticed. Strong monsoon circulation is evinced by NCEP/NCAR over the Oceanic regions and NCMRWF over the landmass. The various mean budgets under consideration indicated this feature invariably. 相似文献
2.
A Study on Climatological Features of the Asian Summer Monsoon: Dynamics, Energetics and Variability 总被引：1，自引：0，他引：1
A continuing goal in the diagnostic studies of the atmospheric general circulation is to estimate various quantities that cannot be directly observed. Evaluation of all the dynamical terms in the budget equations for kinetic energy, vorticity, heat and moisture provide estimates of kinetic energy and vorticity generation, diabatic heating and source/sinks of moisture. All these are important forcing factors to the climate system. In this paper, diagnostic aspects of the dynamics and energetics of the Asian summer monsoon and its spatial variability in terms of contrasting features of surplus and deficient summer monsoon seasons over India are studied with reanalysis data sets. The daily reanalysis data sets from the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) are used for a fifty-two year (1948–1999) period to investigate the large-scale budget of kinetic energy, vorticity, heat and moisture. The primary objectives of the study are to comprehend the climate diagnostics of the Asian summer monsoon and the role of equatorial convection of the summer monsoon activity over India.It is observed that the entrance/exit regions of the Tropical Easterly Jet (TEJ) are characterized by the production/destruction of the kinetic energy, which is essential to maintain outflow/inflow prevailing at the respective location of the TEJ. Both zonal and meridional components contribute to the production of kinetic energy over the monsoon domain, though the significant contribution to the adiabatic generation of kinetic energy originates from the meridional component over the Bay of Bengal in the upper level and over the Somali Coast in the low level. The results indicate that the entire Indian peninsula including the Bay of Bengal is quite unstable during the summer monsoon associated with the production of vorticity within the domain itself and maintain the circulation. The summer monsoon evinces strong convergence of heat and moisture over the monsoon domain. Also, considerable heat energy is generated through the action of the adiabatic process. The combined effect of these processes leads to the formation of a strong diabatic heat source in the region to maintain the monsoon circulation. The interesting aspect noted in this study is that the large-scale budgets of heat and moisture indicate excess magnitudes over the Arabian Sea and the western equatorial Indian Ocean during surplus monsoon. On the other hand, the east equatorial Indian Ocean and the Bay of Bengal region show stronger activity during deficient monsoon. This is reflected in various budget terms considered in this study. 相似文献
3.
利用1979～2003年的NCEP/NCAR再分析资料探讨了亚澳季风区经向气流的季节性分支和结构特征. 结果表明,亚澳季风区经向气流的垂直斜压结构由冬到夏发生季节性转向,即从冬季时的低层北风、高层南风转换为夏季时的低层南风、高层北风. 季节反向的经向气流主体偏向北半球,其区域差异性在对流层中低层更为显著. 以印度半岛和中南半岛为界,亚洲热带季风区中低层经向气流在冬夏季均呈现三通道特征,与此相应,亚澳季风区自西向东存在三支相对独立的经向环流分支,且冬夏季的差异均很显著,如冬季的中心高度自西向东递减、夏季的经向跨度自西向东递增等. 相似文献
4.
亚洲地区是物质由对流层向平流层输送的主要通道,在平流层-对流层交换中扮演着积极的角色. 本文主要利用卫星资料和欧洲中心ERA40再分析资料,借助Wei诊断模式研究亚洲地区夏季上对流层-下平流层(UTLS)水汽分布和平流层-对流层水汽交换特征,重点着眼于水汽交换的年际变化,并探讨其与亚洲夏季风的联系. 结果表明,季风区UTLS水汽较赤道地区偏多,且通过磁带记录信号的传播,可穿越对流层顶影响下平流层水汽的多寡. 夏季平流层-对流层水汽交换表现出明显的年际特征,其年际变化与亚洲季风强弱变化有密切联系,尤其与南亚夏季风的关系更为显著. 在亚洲夏季风影响下,亚洲地区出现异常的大气环流和垂直运动,从而影响平流层-对流层之间水汽的交换. 这些结果对认识其它大气成分的输送过程也具有重要的指示意义. 相似文献
5.
P. L. S. Rao 《Pure and Applied Geophysics》2001,158(5-6):965-988
—?In this paper, we examine the large-scale balances of kinetic energy, vorticity, angular momentum, heat and moisture over the Asian summer monsoon region. The five year (1986–1990) uninitialized daily analyses for the summer season comprising June, July and August (JJA), produced at the European Centre for Medium Range Weather Forecasts (ECMWF) under the aegis of Tropical Ocean and Global Atmosphere (TOGA) have been considered to carry out the study.¶The following features characterize the Asian summer monsoon domain. It acts as the source of kinetic energy as well as vorticity, and sink of heat and moisture. Kinetic energy and vorticity are produced in the monsoon region and transported horizontally. On the contrary, heat and moisture are transported into the monsoon region. The zonal and meridional components of adiabatic generation of kinetic energy contribute to the production of kinetic energy over the Arabian Sea and Bay of Bengal, respectively. The horizontal advection of relative vorticity is balanced by sub-grid scale generation. The angular momentum generated due to pressure torque (east-west pressure gradient) is balanced by the flux convergence of omega momentum. Further, the angular momentum budget delineates that flux convergence of relative momentum is necessary to maintain the surface westerlies against the friction. The horizontal convergence of heat and moisture facilitates enhancement of diabatic heating, and also leads to the formation of diabatic heat sources, which are crucial to sustain the summer monsoon circulation. 相似文献
6.
—The radiative-convective feedback and land-sea thermal forcing play significant roles in maintenance of the summer monsoon circulation over the Indian sub-continent. In this study, the role of radiative transfer in maintaining the monsoon circulation is examined with numerical sensitivity experiments. For this purpose, a sixteen layer primitive equation limited area model is used to perform numerical simulations with and without atmospheric radiative transfer processes parameterized in the model. The initial values and boundary conditions for the numerical integrations of the model are derived from operational analyses of the ECMWF, UK. The results show that the radiative transfer is essential in maintaining the intensity of the low level Somali Jet as well as the upper level Tropical Easterly Jet (TEJ) over the Indian sub-continent and adjoining seas. The meridional circulation over the region is also well simulated. As a result, enough moisture transports from the warm equatorial region to simulate more realistic orographic precipitation in the windward side of the mountains along the West coast of India. Without radiative transfer processes in the model atmosphere the simulated monsoon circulation weakens, moisture transport decreases and the precipitation lessens. 相似文献
7.
本文利用NCEP/NCAR再分析资料,分析了长江流域夏季风期间的水汽收支和循环,着重研究了不同月份与水汽收支的年际变化显著相关的大尺度水汽输送和环流异常.流域范围的西南夏季风水汽输送以6、7月最为强烈,经向输送在5～8月造成流域水汽辐合,9月造成辐散;纬向输送在5～7月造成流域水汽辐散,8、9月造成辐合.研究表明,在不同月份,流域的南北边界处的水汽输送在流域水汽收支的年际变化中起着不同的作用.这种变化与大气环流的异常密切相关.在夏季风相对较弱月份（5、8、9月）,流域水汽收支的年际变化极大地受到流域南边界南风水汽输入通道的影响,对应于水汽收入偏丰年,该3个月500 hPa高空在青藏高原东部都存在显著异常低压区,而且,8、9月在中南半岛及其以东洋面存在显著异常反气旋环流,与8月西太副高的向西向南异常伸展,以及9月副高的西伸较弱和南北范围较宽有关,这些异常环流均造成南边界的大量异常水汽输入.而在夏季风十分强盛的6、7月,流域北边界南风水汽输出极大增加,成为流域水汽收入年际变化的关键敏感通道,对应于水汽收入偏丰年,6月500 hPa高空主要受中纬度以黄海和东海为中心的异常低压系统和气旋性异常环流影响,与该区域副高偏南、偏弱有关,而7月则主要受中高纬以外兴安岭为中心的异常高压和反气旋性异常环流影响,应该是由于该区域大陆高压的频繁生成造成的,它们均造成流域北边界水汽输出的异常减少. 相似文献
8.
An overview of the influence of atmospheric circulation on the climate in arid and semi-arid region of Central and East Asia 总被引：1，自引：0，他引：1
The arid and semi-arid (ASA) region of Asia occupies a large area in the middle latitudes of the Northern Hemisphere, of which the main body is the ASA region of Central and East Asia (CEA). In this region, the climate is fragile and the environment is sensitive. The eastern part of the ASA region of CEA is located in the marginal zone of the East Asian monsoon and is jointly influenced by westerly circulation and the monsoon system, while in the western part of the ASA of CEA, the climate is mainly controlled by westerly circulation. To understand and predict the climate over this region, it is necessary to investigate the influence of general circulation on the climate system over the ASA region of CEA. In this paper, recent progress in understanding the relationship between the general circulation and climate change over the ASA region is systematically reviewed. Previous studies have demonstrated that atmospheric circulation represents a significant factor in climate change over the ASA region of CEA. In the years with a strong East Asian summer monsoon, the water vapor flux increases and precipitation is abundant in the southeastern part of Northwest China. The opposite situation occurs in years when the East Asian summer monsoon is weak. With the weakening of the East Asian summer monsoon, the climate tends to dry over the semi-arid region located in the monsoon marginal zone. Recently, owing to the strengthening of the South Asian monsoon, more water vapor has been transported to the ASA region of Asia. The Plateau summer monsoon intensity and the precipitation in summer exhibit a significant positive correlation in Central Asia but a negative correlation in North China and Mongolia. A significant positive correlation also exists between the westerly index and the temperature over the arid region of CEA. The change in the westerly circulation may be the main factor affecting precipitation over the arid region of Central Asia. 相似文献
9.
In this study an attempt has been made to examine the evolutionary features of the dynamic and thermodynamic characteristics
of the marine atmosphere over the South-East Arabian Sea near 9.22°N, 74.51°E just two to three days prior to the onset of
southwest monsoon over Kerala during 2003 and seek the linkages with the large-scale flow in the lower and middle troposphere
at that time over the region. The marine meteorological data collected onboard ORV Sagarkanya as part of the experiment ARMEX-2003
for 4–8 June, 2003 are used. The monsoon onset over Kerala occurred on 8 June, 2003. The observed changes in the marine atmospheric
boundary layer (MABL) characteristics just two days prior to the onset are discussed. It is observed that the MABL increased
in height up to 4 km on 6 June from an initial height 2.8 km on 5 June. The top of the MABL dried up (Relative Humidity RH
~ 30–40%) with weak and variable winds throughout the day on 6 June while the air at 850 hPa is relatively humid (RH ~ 50–80%)
but not saturated. A sequential increase in RH is associated with a change in the winds from southwesterly to westerly from
6 June onwards until the onset date. The changes in the lower and middle troposphere flow patterns over the Arabian Sea and
Indian region are highlighted. 相似文献
10.
This study addresses an understanding of the possible mutual interactions of sub-seasonal variability of the two neighboring
regional monsoon systems through data analysis. The NCEP/NCAR re-analysis and OLR data for three years was used to reveal
the large-scale organization of convective episodes on synoptic (~5 days) and low frequency (15–50 day) scales. It is found
that synoptic scale organization over both the sectors is influenced by the eastward migration of large-scale convective episodes
associated with the Madden Julian Oscillation (MJO) on the low frequency scale. The organization of convection associated
with the African monsoon on the synoptic scale is influenced by the pulsatory character of lower mid-troposphere and upper
troposphere wind regimes moving westward over the African sector. Over the Indian region formation of low pressure areas and
depressions in the monsoon trough occur in an overlapping manner under an envelope of low frequency seasonal oscillation.
We have also found some correspondence between the summer monsoon rainfall over tropical North Africa and India on a decadal
basis, which would suggest a common mode of multi-decadal variability in the two monsoon systems. The study points out the
need to organize simultaneous field campaigns over the Indian and the African monsoon regions so as to bring out observational
features of possible interactions between the two neighboring systems, which could then be validated through modeling studies. 相似文献
11.
S. Raman U. C. Mohanty N. C. Reddy K. Alapaty R. V. Madala 《Pure and Applied Geophysics》1998,152(4):781-809
—The influence of soil moisture and vegetation variation on simulation of monsoon circulation and rainfall is investigated. For this purpose a simple land surface parameterization scheme is incorporated in a three-dimensional regional high resolution nested grid atmospheric model. Based on the land surface parameterization scheme, latent heat and sensible heat fluxes are explicitly estimated over the entire domain of the model. Two sensitivity studies are conducted; one with bare dry soil conditions (no latent heat flux from land surface) and the other with realistic representation of the land surface parameters such as soil moisture, vegetation cover and landuse patterns in the numerical simulation. The sensitivity of main monsoon features such as Somali jet, monsoon trough and tropical easterly jet to land surface processes are discussed.¶Results suggest the necessity of including a detailed land surface parameterization in the realistic short-range weather numerical predictions. An enhanced short-range prediction of hydrological cycle including precipitation was produced by the model, with land surface processes parameterized. This parameterization appears to simulate all the main circulation features associated with the summer monsoon in a realistic manner. 相似文献
12.
Robert Pincus Anton Beljaars Stefan A. Buehler Gottfried Kirchengast Florian Ladstaedter Jeffrey S. Whitaker 《Surveys in Geophysics》2017,38(6):1399-1423
This paper addresses the representation of lower tropospheric water vapor in the meteorological analyses—fully detailed estimates of atmospheric state—providing the wide temporal and spatial coverage used in many process studies. Analyses are produced in a cycle combining short forecasts from initial conditions with data assimilation that optimally estimates the state of the atmosphere from the previous forecasts and new observations, providing initial conditions for the next set of forecasts. Estimates of water vapor are among the less certain aspects of the state because the quantity poses special challenges for data assimilation while being particularly sensitive to the details of model parameterizations. Over remote tropical oceans observations of water vapor come from two sources: passive observations at microwave or infrared wavelengths that provide relatively strong constraints over large areas on column-integrated moisture but relatively coarse vertical resolution, and occultations of Global Positioning System provide much higher accuracy and vertical resolution but are relatively spatially coarse. Over low-latitude oceans, experiences with two systems suggest that current analyses reproduce much of the large-scale variability in integrated water vapor but have systematic errors in the representation of the boundary layer with compensating errors in the free troposphere; these errors introduce errors of order 10% in radiative heating rates through the free troposphere. New observations, such as might be obtained by future observing systems, improve the estimates of water vapor but this improvement is lost relatively quickly, suggesting that exploiting better observations will require targeted improvements to global forecast models. 相似文献
13.
本文对长江中下游夏季旱涝年前期（3、4、5月的季节平均）和同期（6、7、8月的季节平均）的南半球环流作对比分析,探讨南半球环流异常与长江中下游夏季旱涝的关系. 结果表明前期和同期南半球环流均有显著差异,春季南极涛动对长江中下游旱涝的影响较夏季显著,南半球副热带高压在春、夏两季中有很好季节持续性. 因此,春季南半球环流异常可以作为长江中下游夏季旱涝主要短期气候预测因子. 南、北半球中高纬环流相互作用是长江中下游夏季降水的一个重要因素,其可能的联系机制是从南半球高纬到北半球东亚沿岸经向分布的正压遥相关. 研究中还发现在长江中下游的涝年,整个对流层中南半球春、夏两季有持续增温,这说明了南北半球的温度梯度减弱也是东亚夏季风减弱的原因之一. 相似文献
14.
青藏高原为亚洲季风区的典型代表区域,研究其水汽进入平流层的过程和机理对认识全球气候和大气环境变化具有一定的现实意义. 本文基于中尺度气象模式(WRF)的模拟输出结果(2006年8月20日至8月26)驱动拉格朗日大气输送模式FLEXPART,通过追踪并解析气块的三维轨迹以及温度、湿度等相关物理量的相关变化特征,初步分析了夏季青藏高原地区近地层-对流层-平流层的水汽输送特征. 研究结果表明,源于高原地区近地层的水汽在进入平流层的过程中受南亚高压影响下的大尺度环流和中小尺度对流的共同影响.首先,在对流抬升作用下,气块在短时间内(24 h)可抬升到9~12 km的高度,然后在南亚高压闭合环流影响下,相当部分气块在反气旋的东南侧穿越对流层顶进入平流层中,并继续向低纬热带平流层输送,进而参与全球对流层-平流层的水汽循环过程. 在对流抬升高度上气块位置位于高原的西北侧,然而气块拉格朗日温度最小值主要分布于高原南侧,两个位置上气块的平均位温差值可达15~35 K,这种显著的温度差异将导致气块进入平流层时"脱水". 比较而言,夏季青藏高原地区近地层水汽进入平流层的多寡主要和大尺度汽流的垂直输送有关,而深对流的作用相对较弱. 相似文献
15.
利用1979—2013年NCEP/DOE再分析资料的大气多要素日平均资料、美国NOAA日平均向外长波辐射资料和ERSST月平均海温资料,分析赤道大气季节内振荡(简称MJO)活动对南海夏季风爆发的影响及其与热带海温信号等的协同作用.结果表明,赤道MJO活动与南海夏季风爆发密切联系,MJO的湿位相(即对流活跃位相)处于西太平洋位相时,有利于南海夏季风爆发,而MJO湿位相处于印度洋位相时,则不利于南海夏季风爆发.赤道MJO活动影响南海夏季风爆发的物理过程主要是大气对热源响应的结果,当MJO湿位相处于西太平洋位相时,一方面热带西太平洋对流加强使潜热释放增加,导致处于热源西北侧的南海—西北太平洋地区对流层低层由于Rossby响应产生气旋性环流异常,气旋性环流异常则有利于西太平洋副热带高压的东退,另一方面菲律宾附近热源促进对流层高层南亚高压在中南半岛和南海北部的建立,使南海地区高层为偏东风,从而有利于南海夏季风建立;当湿位相MJO处于印度洋位相时,热带西太平洋对流减弱转为大气冷源,情况基本相反,不利于南海夏季风建立.MJO活动、孟加拉湾气旋性环流与年际尺度海温变化协同作用,共同对南海夏季风爆发迟早产生影响,近35年南海夏季风爆发时间与海温信号不一致的年份,基本上是由于季节转换期间的MJO活动特征及孟加拉湾气旋性环流是否形成而造成,因此三者综合考虑对于提高季风爆发时间预测水平具有重要意义. 相似文献
16.
本文利用"模式手术"方法研究了西北太平洋热带气旋(TC)对东亚—西北太平洋区域大尺度环流的影响.结果表明,夏季频繁的西北太平洋TC活动导致东亚夏季风增强,季风槽加深;西太平洋副热带高压东退,位置偏北;东亚副热带高空急流强度增强,北太平洋(东亚大陆)上急流轴偏北(偏南);热带地区(副热带地区)的对流层中低层出现异常上升气流(下沉气流),并且从低纬向高纬呈现异常上升气流和异常下沉气流交替分布特征.在中国东南沿海,TC降水导致夏季降水量明显增加;而在长江中下游和华北地区,TC活动引起的异常下沉气流使夏季降水量显著减少.因此,夏季西北太平洋TC活动对东亚—西北太平洋区域气候有显著影响. 相似文献
17.
This study examines the short-range forecast accuracy of the Pennsylvania State University-National Center for Atmospheric
Research Mesoscale Model (MM5) as applied to the July 2006 episode of the Indian summer monsoon (ISM) and the model's sensitivity
to the choice of different cumulus parameterization schemes (CPSs), namely Betts-Miller, Grell (GR) and Kain-Fritsch (KF).
The results showed that MM5 day 1 (0–24 h prediction) and day 2 (24–48 h prediction) forecasts using all three CPSs overpredicted
monsoon rainfall over the Indian landmass, with the larger overprediction seen in the day 2 forecasts. Among the CPSs, the
rainfall distribution over the Indian landmass was better simulated in forecasts using the KF scheme. The KF scheme showed
better skill in predicting the area of rainfall for most of the rainfall thresholds. The root mean square error (RMSE) in
day 1 and day 2 rainfall forecasts using different CPSs showed that rainfall simulated using the KF scheme agreed better with
the observed rainfall. As compared to other CPSs, simulation using the GR scheme showed larger RMSE in wind speed prediction
at 850 and 200 hPa over the Indian landmass. MM5 24-h temperature forecasts at 850 hPa with all the CPSs showed a warm bias
of the order of 1 K over the Indian landmass and the bias doubled in 48-h model forecasts. The mean error in temperature prediction
at 850 hPa over the Indian region using the KF scheme was comparatively smaller for all the forecast intervals. The model
with all the CPSs overpredicted humidity at 850 hPa. The improved prediction by MM5 with the KF scheme is well complemented
by the smaller error shown by the KF scheme in vertical distribution of heat and mean moist static energy in the lower troposphere.
In this study, the KF scheme which explicitly resolve the downdrafts in the cloud column tended to produce more realistic
precipitation forecasts as compared to other schemes which did not explicitly incorporate downdraft effects. This is an important
result especially given that the area covered by monsoon-precipitating systems is largely from stratiform-type clouds which
are associated with strong downdrafts in the lower levels. This result is useful for improving the treatment of cumulus convection
in numerical models over the ISM region. 相似文献
18.
A. K. Mitra L. Stefanova T. S. V. Vijaya Kumar T. N. Krishnamurti 《Pure and Applied Geophysics》2005,162(8-9):1431-1454
Seasonal climate prediction for the Indian summer monsoon season is critical for strategic planning of the region. The mean features of the Indian summer monsoon and its variability, produced by versions of the ‘Florida State University Coupled Ocean-Atmosphere General Circulation Model’ (FSUCGCM) hindcasts, are investigated for the period 1987 to 2002. The coupled system has full global ocean and atmospheric models with coupled assimilation. Four member models were created by choosing different combinations of parameterizations of the physical processes in the atmospheric model component. Lower level wind flow patterns and rainfall associated with the summer monsoon season are examined from this fully coupled model seasonal integrations. By comparing with observations, the mean monsoon condition simulated by this coupled model for the June, July and August periods is seen to be reasonably realistic. The overall spatial low-level wind flow patterns and the precipitation distributions over the Indian continent and adjoining oceanic regions are comparable with the respective analyses. The anomalous below normal large-scale precipitation and the associated anomalous low-level wind circulation pattern for the summer monsoon season of 2002 was predicted by the model three months in advance. For the Indian summer monsoon, the ensemble mean is able to reproduce the mean features better compared to individual member models. 相似文献
19.
Based on analysis and simulation, the interaction of thermal forcing between the Tibetan Plateau (TP) and Iranian Plateau (IP) in summer is investigated. Associated influences on water vapor transport in the Asian subtropical monsoon region and the formation of a cold center in the lower stratosphere over Eurasia are also investigated. Results show that surface sensible heating (SH) over the two plateaus not only have mutual influences but also feedback to each other. SH over the IP can reduce the SH and increase the LH over the TP, whereas the SH over the TP can increase surface heating over the IP, thereby reaching quasi-equilibrium among the SH and LH over the TP, IP SH and atmosphere vertical motion. Therefore, the so-called Tibetan-Iranian Plateau coupling system (TIPS) is constructed, which influences atmosphere circulation. In the TIPS system, interaction between surface SH and LH over the TP plays a leading role. SH of the IP and TP influences on other regions not only have superimposed effects but also mutually offset. Accounting for contributions to the convergence of water vapor transport in the Asian subtropical monsoon region, TP SH contributes more than twice that of the IP. The combined influence of SH over TP and IP represents the major contribution to the convergence of water vapor transport in that region. In addition, the heating effect of TIPS increases the upper tropospheric temperature maximum and lifts the tropopause, cooling the lower stratosphere. Combined with large-scale thermal forcing of the Eurasian continent, the TIPS produces a strong anticyclonic circulation and the South Asian High that warms the upper troposphere and cools the lower stratosphere, thereby affecting regional and global weather and climate. 相似文献
20.
Moisture budget variations in the Yangtze River Basin, China, and possible associations with large-scale circulation 总被引：3，自引：2，他引：1
Zengxin Zhang Hui Tao Qiang Zhang Jinchi Zhang Nicola Forher Georg Hörmann 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):579-589
We analyzed seasonal and annual variations of the whole layer atmospheric moisture budget and precipitation during 1961–2005
and their associations with large-scale circulation in the Yangtze River basin, China. The results indicated increasing moisture
budget in summer and winter, but decreasing moisture budget in spring and autumn. Positive correlations between moisture budget
and precipitation illustrate tremendous impacts the moisture budget has on the precipitation changes across the Yangtze River
basin. In terms of seasonal variations, significant correlations were observed between precipitation and moisture budget in
spring and autumn in the upper Yangtze River basin. Besides, we also analyzed changes of geopotential height. The positive
trends of the geopotential height (850 hPa) were observed in the East Asia and the negative trends in the middle and west
Pacific Ocean, indicating increasing geopotential height from south to north in east Asia which largely limited the moisture
propagation to north China. While decreasing meridional geopotential height from west to east along the Yangtze River basin
caused more moisture propagation from the west to the east parts of the study region, which may benefit more precipitation
in the middle and lower Yangtze River basin. 相似文献