【作者】 刘晓云；

【导师】 李栋梁； 王劲松；

【作者基本信息】 南京信息工程大学 ， 气象学， 2012， 硕士

【摘要】 基于整理的中国589站50年(1961-2010年)的月降水、温度观测资料、美国气象环境预报中心和国家大气研究中心(NCEP/NCAR)提供的再分析资料和NOAA提供的海表温度(Sea Surface Temperature,简写SST)资料,通过计算干旱指数(DroⅠ),并采用REOF、小波、回归、合成、相关分析等方法,分析了近50a中国区域干湿变化的时空分布特征,研究了大尺度环流异常对第一显著干旱异常区(黄土高原中部)秋季干湿变化的影响,并对黄土高原中部干旱成因进行了深入探讨。文章取得的主要成果有：(1)中国区域可划分为16个主要干旱异常区。河套-华北(黄土高原中部)为第一显著异常区。通过对黄土高原中部四季标准化干旱指数作倾向分析,发现秋季干旱化趋势最为显著。(2)通过对黄土高原中部秋季DroⅠ年际(周期≤8a)和年代际(周期>8a)两种时间尺度对应的大气环流分析发现：年际尺度上表现为欧亚大陆中高纬的双阻型；200hPa西风急流显著减弱北移；日本海-鄂霍茨克海为反气旋控制,反气旋底部存在一致的偏东水汽输送输入研究区。年代际尺度上东亚大陆为一致的低值系统；200hPa东亚副热带西风急流减弱北移,但减弱程度没有年际尺度上明显；研究区水汽主要由中纬度的西风水汽输送以及经孟加拉湾在中南半岛转向的南风水汽输送组成。上述环流场的配置有利于黄土高原中部秋季偏湿情景,相反的异常分布对应的是黄土高原秋季偏干状况。(3) Nino3区SST指数(Nino3Ⅰ)超前黄土高原中部秋季DroⅠ5个月已经呈现显著的负相关关系,而孟加拉湾—中国南海SST指数(BayⅠ)超前3个月时便与DroⅠ呈现显著的负相关关系；在年际时间尺度上,秋季Nino3Ⅰ、BayⅠ均与DroⅠ存在显著相关(准4a,4～6a)；在年代际尺度上,只有BayⅠ与DroⅠ存在显著相关性(准10a)。(4) DroⅠ与夏季亚洲-太平洋涛动(APO)之间存在显著的正相关关系。夏季APO异常变化可以影响秋季大气环流进而对黄土高原中部干湿变化产生重要作用。因此,夏季APO的强度可以看作是黄土高原中部秋季旱涝预测的一个重要信号。更多还原

【Abstract】 Based on the monthly mean rainfall and temperature of589China stations,the National Centers for Environmental Prediction/National Centers for Atmospheric Research (NCEP/NCAR) reanalysis dataset and NOAA extended reconstructed SST data from1961to2010, the temporal evolution and spatial distribution of drought over China under global warming. The assosicated large-scale circulation anomalies and reasons are investigated over the middle Loess plateau drought with rotated empirical orthogonal function(REOF), wavelet transform, regression, composite and correlation methods. The main conclusions are as follows:The spatial characteristics of annual standard drought index can be divided into sixteen climatic subareas in China region under global warming. The middle Loess plateau is the first anmoly area. The seasonal drought index linear trend is analysed and the autumn standard drought trend is the significant (-0.29/10a).In this study two time scales are separated by:whose period is shorter than eight years as inerannual component,and whose period is longer than eight years as interdecadal component. The atmospheric circulation patterns associated with these two modes are quite different.The atmospheric circulation anomalies associated with the wet over the middle Loess plateau of the interannual component include the double blockings of mid-high latitude and the westerly jet streams shows significant negative, and the northeastern Pacific and Japan-Okhotsk Sea anticyclone is featured with an equivalent barotropic structure,and the east wind at the bottom of the anticyclone provided favorable moisture for the middle Loess plateau.And that of the interdecadal component include the negative geopotential height anomaly over East Asian and the East Asian subtropical westerly jet stream(EAWJ)turns to be weaken and northward, and the westerly water vapor transport in the middle latitude and The moisture transport that roots in the Arabian Sea and the Bay of Bengal, Turning northward at the Indo-China Peninsula, had very important contribution to the variability of the atmospheric water resource over the middle Loess plateau.Bay of Benga and South China Sea SST index (BayI) negatively correlates with the standard drought index over the middle Loess plateau in autumn(DroI) when Bayl lead DroI for5months. Nino3index(NinoI) negatively correlates with DroI when NinoI lead Drol for3months. It is found that the significant connections exist mainly at the inter-annual timescale of quasi～4a and4-6a, representing the relationships between the inter-annual BayI (Ninol) and the DroI,and significant connections exist at the interdecadal timescale of quasi～10a between BayI and DroI.The linkage between Asian-Pacific oscillation (APO)and the wet/drought over the middle Loess plateau in autumn is preliminarily addressed by using of the observed data.Results show that they correlate very well,with the positive/ngetive phase of APO tending to wet/drought the over the middle Loess plateau.Such a relationship can be explained by the autumn atmospheric circulation change over Aisian and the North Pacific in association with the anomalous summer APO. So, The summer APO variation provides a potential valuable signal for predicting the autumn wet/drought over the middle Loess plateau.更多还原