【作者】 施晓晖；

【导师】 徐祥德；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 博士

【摘要】 在全球变暖的背景下,气候变化对环境、水资源、工农业生产和人民生活的影响日益显著,并越来越受到人们的关注。为了解近40年来中国区域气候及东亚季风的年代际变化规律及其成因,本文以揭示气候基本要素的空间结构及其年代际演变特征为主要目标,采用统计-动力综合分析方法(趋势转折判别模型、相关分析、EOF-SVD综合分析等),分析了中国大陆气候型年代际演变趋势及其转折特征;重点研究了东亚冬、夏季风的年代际时空演变特征和全球变暖背景下东亚区域的非均匀热力空间结构年代际演变特征,并分析了两者之间的相关联系;研究了中国东部日照时数、低云量等气象要素的年代际演变特征,初步探讨了气溶胶区域气候效应及其与东亚季风年代际变化的相关联系;并采用区域气候模式对东亚海陆热力差异演变特征的影响效应进行了模拟试验。本文获取了以下主要研究结果:NCEP/NCAR再分析资料可信度分析:本文采用计算标准化均方根误差、相关分析以及EOF分解等多种客观分析统计方法,讨论了NCEP/NCAR再分析资料在中国区域气候变化研究中的可信度的季节特征及其空间差异。从时间上看,NCEP/NCAR再分析风速资料在春、夏、秋季具有一定的可信度,但冬季的可信度较差;表面气温则是冬季的可信度最好,夏季的可信度较差。从空间来看,NCEP再分析风速、表面气温资料在中国东部地区的可信度均好于西部,表现出较显著的区域性差异特征,且随着高度升高,风速资料的可信度增大。气候型年代际转折空间结构特征:采用趋势转折判别模型对1961～2000年中国区域站点及分区的冬、夏季气候型年代际转折特征进行了分析。通过逐站检验,揭示了站点“群体”气候型年代际转折的区域“同步性”特征,即气候型年代际转折发生年份相近,且转折后趋势一致的站点呈明显的带状区域分布。站点“群体”及分区气候型的年代际转折检验结果表明,冬季气温由降温趋势转为增温趋势年代际转折的发生时间北方早于南方,夏季则是北方晚于南方,但转折后冬、夏季的增温趋势均为北方地区比南方地区显著;夏季降水最近一次的年代际趋势转折大多发生在20世纪80年代,转折后南方大部地区为增加趋势,北方除了西北地区西部外以减少趋势为主,呈显著的“南涝北旱”变化趋势。区域气候与东亚季风空间结构年代际演变特征:利用1961～2000年NCEP/NCAR更多还原

【Abstract】 Under global warming background, the impacts of climate change on environment, water resource,agriculture, industry and people’s life are becoming more and more remarkable and drawing more andmore attention. In order to study the change laws and their causes of regional climate in China and EastAsia monsoon (EAM) in recent 40 years, it is very necessary and urgent to disclose the spatial structureand its interdecadal change (IC) features of climatic basic factors. In virtue of the statistic-dynamicsynthetical methods such as climatic trend turning discriminating model (PLFIM), correlation analysis,EOF-SVD compositive analysis, this paper analyzes the ICs and trend turning characteristics of climatemodes in China, with emphases on the researches of spatial-temporal features of the ICs of EAM andthe heterogeneous thermal structure in East Asia under global warming and the correlation of ICsbetween EAM and the sea–land thermal difference in East Asia–West Pacific (SLTD). In addition, wealso studied the IC characters of meteorologic factors, such as sunshine duration and low cloud cover(LCC) etc. in East China and discussed the relations between IC of EAM and regional climate effect ofaerosol. Finally, the RegCM3 is used to investigate the influence effects of the changes of SLTD.The confidence of NCEP/NCAR reanalysis data: The seasonal characters and spatial differencesof the confidence of NCEP/NCAR reanalysis data in China are studied by using varied statisticalmethods, such as normalized root mean square (RMS), correlation analysis and empirical orthogonalfunction analyze (EOF) etc. Viewed from time, the confidence of reanalysis wind data in spring,summer and autumn is preferable, but that in winter is worse. The confidence of surface air temperature(SAT) data is best in winter and worst in summer. Viewed from space, the confidences of reanalysiswind and SAT data in eastern China are better than those in western China. Along with the heightincreases, the confidence of reanalysis wind data is better.The spatial structures of interdecadal turning of climate modes: Using climatic trend turningdiscriminating model (PLFIM), the interdecadal turnings of climate modes (CMIT) in winter andsummer of varied stations and sub-regions in China during 1961?2000 have been investigated. Resultsshow that the stations with close occurrence years of CMIT and coincident trends after the turningsexhibit a zonal distribution, indicating a notable regional “in-phase” feature. The test results of stationsand sub-regions show that the occurrence time of interdecadal trend turning (ITT) of temperature fromdecrease to increase in northern China is earlier than that in southern China in winter, while theoccurrence time in northern China is later than that in southern China in summer. The warming trendafter turning in northern China is more significant than that in southern China in both winter andsummer. The last ITTs of summer precipitation mostly occur in 1980s;afterwards, summer precipitationincreases in southern China and decreases in northern China except in Northwest China, exhibiting anotable “south-flooding and north-drought” trend.The interdecadal change characteristics of spatial structures of regional climate and EAM:The temporal and spatial distributions of the IC of EAM and SLTD in recent 40 years and theirrelationship are studied based on NCEP/NCAR reanalysis data and monthly observational data in China,such as SAT and precipitation, and using some statistic methods, such as running mean, correlationanalysis and EOF-SVD compositive analysis. Results suggest that the first eigenvector of interdecadalcomponent (FEIC) of sea level pressure (SLP) in winter displays a “negative in north and positive insouth” spatial structure, and its time coefficient (TC) happens a turning from negative to positive in thelast 1970s, reflecting the weakening and southward extending of East Asia winter monsoon (EAWM).The FEIC of SAT in winter exhibits a spatial distribution with distinctive warming over northern landand little change over southern land and sea, and its TC occurs a turning from negative to positive in theearly 1980s, suggesting the change of SLTD with decreasing in north and increasing in south. Theinterdecadal spatial-temporal changes (ISTC) of the above two meteorological elements are inaccordance, indicating the close correlation between the IC of EAWM and the ISTC of SAT in winter.Using SVD, it is found that the interdecadal correlation between SLP and SAT in winter over land ismore significant than that over sea, suggesting the IC of EAWM may be a regional response of theclimate in East Asia to the heterogeneous spatial structure of global warming. According to the analysisresults of ISTC of SAT in spring and 850hPa wind in summer and their correlation, it is discovered thatthe southerly at 850hPa over eastern China weakens decade by decade. The FEIC of 850hPa windexhibits the northerly or east-northerly anomalies in the eastern of East Asia, South China Sea and theeastern of Bay of Bengal, suggesting the weakening of East Asia summer monsoon (EASM). The year1978 is the turning point when its TC turns from negative to positive;that is to say, the EASM becomesweak after this year. The FEIC of SAT in spring displays a spatial structure with “positive in north andnegative in south” over land and positive over sea, indicating the decreasing of SLTD in spring. Its TCalso occurs a turning from negative to positive in 1978, suggesting that on the interdecadal time scale,SLTD between the south of East Asia and the West Pacific is characterized by two periods with differentintensity and they are consistent with the two periods with varied intensity of EASM. The results bySVD also show that there exists an important relation between the interdecadal weakening trend ofEASM and the ISTC of SAT in spring. As a whole, the interdecadal weakening trend of EASM isclosely correlated to the heterogeneous spatial structure of SAT over East Asia-West Pacific in spring.The spatial evolution of aerosol and its regional climatic effects: The primary discussion onaerosol influence domains and their regional climatic effects in Beijing and its peripheral in winter andEast China in summer half year in recent about 20 years are performed, and the viewpoint that aerosolregional climatic effect have a certain spatial range is proposed in this paper. Results show that thereexists an aerosol influence domain in Beijing and its south peripheral and the IC of sunshine duration,LCC and fog days show a distinctive difference within and out of the aerosol influence domain inwinter. The regional climate changes including decreasing sunshine duration, increasing LCC and fogdays exist in Beijing and its south peripheral, which are consistent with such trend that aerosol opticaldepth (AOD) in this region increases in recent 20 years. It is found in further investigation that thecorrelation coefficient fields of AOD with sunshine duration and SAT in summer half year in easternChina show a “south negative and north positive” distribution and the significant negative correlationregion is located in the south of eastern China that is also the significant positive correlation regionbetween AOD and LCC, which is similar to the marked interdecadal increasing region of summerprecipitation. It denotes that the regional climatic effects including increasing LCC and precipitation butdecreasing sunshine duration and SAT in summer half year might be caused by increasing aerosol in thesouth of eastern China. It also suggests that in summer half year, the aerosol influence domain overeastern China is located in its south. By calculating the correlation coefficients of AOD with verticalvelocity and meridional wind in summer half year in eastern China, it is found that the regional climaticeffects of aerosol have some impacts on the EASM.The response of regional climate to the change of SLTD: Shown for the sensitivityexperiments by RegCM3, it will cause reduction of east-west direction SLP difference and weakeningof low level northerly wind if winter long wave cooling rate over the northeast of East Asia is decreasedin RegCM3, which indicates that the regional climatic response to greenhouse effect is a possiblereason of the weakening of EAWM. In RegCM3, decreasing SAT over the southeast China andincreasing SAT over the ocean to south of China will lead to the weakening of the intensity of WestPacific subtropical high and leaning to south of its location in summer, as well as the weakening ofEASM. Furthermore, it will cause the “south-increasing and north-decreasing” distribution of summerprecipitation in East China. It is similar to the simulation result of the sensitivity experiment withdecreasing solar heating rate over the south of eastern China in spring and summer. These resultssuggest that the regional climatic response to the change of SLTD associated with aerosol influenceeffect is related to the variety of EASM intensity. These simulation results of sensitivity experimentsreasonably validate the diagnosis results of the ISTC of EAM.更多还原