我国西北地区近50年降水和温度的变化

用近50年的每月温度和降水资料研究了我国西北地区的气候变化.结果表明:(1)该地区在1986年附近发生了一次明显的气候跃变,要比全国气候跃变晚6～8年;(2)跃变后比跃变前全区年平均气温上升了0.51℃,冬季上升了1.27℃;(3)跃变后比跃变前全区年降水总量上升了5.2%,夏季上升了6.8%.进而讨论了温度和降水的增加对该地区生态环境的影响.     

西南气候跃变及影响因子分析

通过ＥＯＦ展开，利用Ｍａｎｎ－Ｋｅｎｄａｌｌ方法，并结合Ｙａｍａｎｏｔ检验，对近４２年西南地区气温和降水进行了跃变分析。结果表明，年平均气温在１９６２年发生暖转冷强跃变，年平均降水无跃变发生。在此基础上，对高原加热指数、南方涛动指数、五组副高指数进行跃变分析，讨论了这些因子与西南气候跃变的联系，发现西南气温跃变的主要影响因子是：副高脊线位置和副高西伸点。     

济南市近80年来降水趋势变化及跃变的初步分析

本文分析了济南市近８０年来的降水趋势变化特征。结果表明，年降水大致呈“平减增减增”的变化趋势；夏季降水变化同年降水变化趋势基本一致；冬季降水先增多后减少。另外，引用气候跃变的概念，采用滑动的均值差异假设检验，对济南市的降水资料（１９１６～１９９６年）进行分析，发现年降水和夏季降水在１９６０年前后跃变增多，在１９６４年前后跃变性减少；冬季降水在１９４７年前后出现了跃变增多的现象。周期图分析表明，济南市降水的跃变具有明显的周期性     

近百年ElNino/LaNina事件与北京气候相关性分析

通过对近百年El Nino/La Nina事件与北京气候相关性研究发现，El Nino/La Nina事件与北京夏季（6－8月）降水、平均最高气温（7月）和冬季（1月）平均最低气温之间相互关系显著。El Nino事件与夏季降水、冬季平均最低气温呈负相关，与夏季平均最高气温呈正相关，造成降水减少，气温年较差较大，大陆性增强的气候特点。La Nina事件与夏季降水、冬季平均最低气温呈正相关，与夏季平均最高气温呈负关，使降水增加，气温年较差减小，大陆性减弱的气候特点。     

我国东部夏季气侯基本态特征研究

利用１８８１年～１９９８年２９个观测站的夏季降水、气温资料,研究了我国东部夏季降水、气温大于３０年的慢变平均值（气候基本态）的变化特征。用经验正交分解方法研究了夏季降水与气温的气候基本态的特征模态及时间演变规律。结果表明,我国东部夏季降水、气温的气候基本态与我国夏季天气及夏季大气活动中心的气候基本态关系密切。     

我国东部夏季气侯基本态特征研究

利用１８８１年￣１９９８年２９个观测站的夏季降水、气温资料,研究了我国东部夏季降水、气温大于３０年的慢变平均值（气候基本态）的变化特征。用经验正交分解方法研究了夏季降水与气温的气候基本态的特征模态及时间演变规律。结果表明,我国东部夏季降水、气温的气候基本态与我国夏季天气及夏季大气活动中心的气候基本态关系密切。     

60年代夏季海平面气压跃变及其与我国夏季温度,降水的相关分析

本文采用我国不同地理区域的４８个站１９５１－１９８８年月平均海平面气压资料，用主相关型和ＥＯＦ的分析，揭示了我国夏季海平面气压在６０年代发生大规模气候跃变的事实。其主信号空间结构特征为，除青藏高原外，全国大部地区海平面气压均为同相变化。东北区，长江中下游区和新疆区为主要气候跃变出现时间先于近表面层温度和降水场。     

北太平洋海温的气候跃度及其对中国汛期降水的影响

应用滑动Ｔ检验方法对北太平洋海温１０年际的气候跃变进行了研究，指出在７０年代末至８０年代初确实存在着一次明显的气候跃变，而跃变前后北太产洋海温结构，厄尔尼诺事件的发展过程都明显不同，进而讨论了北太平洋海温跃变前后对我国６－８月汛期降水量的影响，指出海温跃变前我国汛期降水量在东北地区偏少，华北偏多，长江流域偏水，华南偏多，而跃变后则相反。     

吉林省夏季降水的气候跃变及其与印巴季风低压相关的分析

本文利用气候跃变的分析方法,对夏季吉林省降水量,印巴地区海平面气压距平值及500hPa高度距平值进行了分析。结果表明,它们在1967年前后均有气候跃变(或准气候跃变)出现。印巴地区夏季的海平面气压距平值和500hPa高度距平值均有超前吉林省夏季降水量一年的共同准周期变化,两者距平符号的持续性对吉林省夏季的降水有一定的影响。     

辽宁夏季气温降水气候分区研究

应用聚类分析方法，以气候平均为辅，对1961～2000年辽宁53个测站的夏季气温和降水资料进行标准化处理，并根据各站之间的相关程度差异和气候特点，对辽宁夏季平均气温和平均降水进行气候分区。结果表明：辽宁夏季气候特点为，降水东部多西部少；气温中北部偏高，南部沿海凉爽。     

Warm and cold events in the southeast Atlantic/southwest Indian Ocean region and potential impacts on circulation and rainfall over southern Africa

Summary An important pattern of interannual variability in the southern African region is one where sea surface temperature (SST) in neighbouring waters, particularly in the Agulhas Current, its retroflection region and outflow across the southern midlatitudes of the Indian Ocean, is anomalously warm or cool. Evidence exists of significant rainfall anomalies over large parts of southern Africa during these warm or cool SST events. Here, a general circulation model is used to study the response of the atmosphere in the region to an idealised representation of these SST anomalies. The induced atmospheric circulation and precipitation anomalies over the adjacent southern African landmass on intraseasonal through to interannual time scales are investigated.A nonlinear response to the SST anomalies is found in that the changes to the model atmosphere when warm SST forcing is used are not the reverse (in either pattern or magnitude) to that when cold SST forcing is imposed. For the warm SST anomaly, it is found that the atmospheric response is favourable for enhancement of the original SST anomaly on scales up to, and including, annual. However, as the scale becomes interannual (i.e., 15–21 months after imposition of the anomaly), the model response suggests that damping of the original SST anomaly becomes likely. However, no such coherent timescale dependent response is found when the cold SST anomaly is impose. It is suggested that the relationship of the SST anomaly to the background seasonal climatology may help explain this fundamental difference in the response.Examination of the circulation and rainfall patterns under warm SST forcing indicates that there are significant anomalies over large parts of southern Africa on all scales from intraseasonal through to interannual. On the south coast, rainfall anomalies result from enhanced evaporation of moisture off the SST anomaly. Over the interior, changer in the convergence of moist air streams together with suggestions of a shift in the Walker circulations between southern Africa and the bordering tropical South Atlantic and Indian Oceans appear to be associated with the rainfall anomalies. Similar mechanisms of rainfall perturbation are found when the cold SST anomaly is imposed; however, there is a significant response only on intra-annual to interannual scales. In all cases, the magnitude of the rainfall anomalies accumulated over a 90 day season were of the order of 90–180 mm, and therefore represent a significant fraction of the annual total of many areas. These model results re-inforce previous observational work suggesting that SST anomalies south of Africa, particularly in the retroflection region of the Agulhas Current, are linked with significant rainfall anomalies over the adjacent subcontinent.With 12 Figures     

Diurnal responses of tropical convective and stratiform rainfall to diurnally varying sea surface temperature

Two experiments were carried out using a two-dimensional cloud-resolving model to study the effects of diurnally varying sea surface temperature (SST) on diurnal variations of tropical convective and stratiform rainfall. Experiment SST29 is imposed by a constant SST of 29°C, whereas experiment SST29D is imposed by a diurnally varying SST with a time-mean of 29°C and a diurnal difference of 1°C. Both experiments are also zonally uniformly imposed by a zero vertical velocity and a constant zonal wind, and are integrated for 40 days to reach quasi-equilibrium states. The model domain mean surface rain rate is larger in SST29D than in SST29 in the late afternoon, when the ocean surface is warmer in SST29D. Convective-stratiform rainfall partitioning analysis reveals that the late-afternoon convective rainfall is larger in SST29D than in SST29, whereas the stratiform rainfalls are similar in both experiments. Further analysis of surface rainfall and cloud microphysical budgets over convective regions shows that, in the late afternoon, the larger amount of water vapor is pumped into the non-raining region through the larger surface evaporation associated with the warmer SST. This water vapor is then transported into convective regions to produce more vapor condensation and greater collection of cloud water by raindrops and larger convective rainfall in SST29D than in SST29.     

Indo-Pacific remote forcing in summer rainfall variability over the South China Sea

This study investigates summer rainfall variability in the South China Sea (SCS) region and the roles of remote sea surface temperature (SST) forcing in the tropical Indian and Pacific Ocean regions. The SCS summer rainfall displays a positive and negative relationship with simultaneous SST in the equatorial central Pacific (ECP) and the North Indian Ocean (NIO), respectively. Positive ECP SST anomalies induce an anomalous low-level cyclone over the SCS-western North Pacific as a Rossby-wave type response, leading to above-normal precipitation over northern SCS. Negative NIO SST anomalies contribute to anomalous cyclonic winds over the western North Pacific by an anomalous east–west vertical circulation north of the equator, favoring more rainfall over northern SCS. These NIO SST anomalies are closely related to preceding La Niña and El Niño events through the “atmospheric bridge”. Thus, the NIO SST anomalies serve as a medium for an indirect impact of preceding ECP SST anomalies on the SCS summer rainfall variability. The ECP SST influence is identified to be dominant after 1990 and the NIO SST impact is relatively more important during 1980s. These Indo-Pacific SST effects are further investigated by conducting numerical experiments with an atmospheric general circulation model. The consistency between the numerical experiments and the observations enhances the credibility of the Indo-Pacific SST influence on the SCS summer rainfall variability.     

印度洋春、夏季海温对西藏高原夏季降水的影响

利用NCEP提供的1950—1997年全球月平均海表面温度场资料，首先通过EOF分解得到不同季节印度洋海温场空间分布特征，并在此基础上使用合成分析、相关分析和SVD分解等多种方法讨论了印度洋前期和同期海温异常与西藏高原夏季降水变化的关系。寻找出影响高原夏季降水的关键海区，目的为高原夏季早涝预测提供参考依据。     

江淮流域梅雨期降水的空间非均匀分布与前期海温的关系

利用中国气象局提供的1978-2007年全国753站逐日降水资料、NECP/NCAR提供的逐日再分析资料和NOAA提供的第2套扩展重建海温资料,从区域整体角度确定了近30 a（1978-2007年）江淮流域梅雨期.采用EOF（empirical orthogonal function,经验正交函数）分析,讨论了江淮流域梅雨期降水空间非均匀分布特征,着重研究了影响江淮梅雨空间非均匀分布的前期海温关键区及关键时段.结果表明：全区一致梅雨旱涝与前期冬季北太平洋鄂霍次克海附近的海温异常有密切的联系.当前期冬季该海域海温偏高时,冬季风偏弱,对应后期梅雨一致偏涝,反之则偏旱.5月南海至台湾和菲律宾以东附近海温偏低,江淮流域梅雨量偏多,反之则偏少.梅雨的南北反相分布与前期秋冬季中印度洋的海温有非常密切的关系,当前一年10月至当年1月中印度洋海温偏高时,梅雨期850 hPa江淮之间易形成切变线,有利于梅雨区“南旱北涝”,反之则“南涝北旱”.梅雨的东西反相分布与前期秋、冬季热带中东太平洋的海温关系密切,ENSO事件有可能通过影响西太平洋副热带高压的东西位置,从而引起东亚大气环流异常,导致梅雨东西分布反相.前期秋季和冬季热带中东太平洋海温偏高年（对应ENSO暖事件）,西太副高位置偏西,有利于梅雨区“东旱西涝”,反之则“东涝西旱”.     

降水对热带海表温度异常的邻域响应 I．数值模拟

基于低阶大气环流谱模式，本文设计了太平洋及印度洋４个不同海域的海表温度异常试验，去研究大气环流及降水对热带海表温度异常强迫作用的“同时”性响应。结果表明尽管暖性的海表温度异常均激发出低空辐合及高空辐散，但在不同海域所激发的异常流场却差异甚大。不过降水异常均发生在海表温度异常区及其毗邻处。它在对称的ＳＳＴＡ区的分布一般是非对称的。对水汽收支的分解分析表明，海表温度异常区异常降水的大小主要由异常的低空辐合决定，而异常降水的分布形态则由异常的水汽平流过程所决定。由于异常的低空辐合及异常的水汽平流过程主要发生在海表温度异常区及毗邻处，因此，降水对热带海表温度异常的响应基本Ｌ是一种邻域响应。它发生在气候平均低空气流沿海表温度异常的下风方向，或在海表温度异常所激发的低空异常气流沿气候平均海温降低的方向。     

我国夏季降水与全球海温的耦合关系分析

利用我国160个台站从1951~2000年的月降水观测资料和NCEP/NCAR的全球海表温度(SST)资料,分析了我国夏季(6、7、8月)降水的时空变化特征及其与海温的相关,并应用奇异值分解(SVD)方法研究了我国夏季降水分布异常与海温变化的耦合关系。结果表明,我国夏季降水异常的雨型分布主要有3种,这些雨型的时间变化除了有明显的年际变化外,还存在显著的年代际变化。尤其是华北地区的降水从1965年左右开始减少,特别是大约1976年后有显著的减少。SVD分析揭示的我国夏季降水和全球海温异常的耦合关系表明,这种耦合关系最主要的时空变化特征表现在年代际变化的时间尺度上。我国华北和东北南部的夏季降水从1976年前后明显减少,与之显著关联的海温异常的关键区包括太平洋、印度洋以及热带和南大西洋。特别是热带中、东太平洋,印度洋,以及热带和南大西洋海水,从1976年前后也明显增暖。本研究揭示的华北持续干旱与印度洋和大西洋海温的年代际变化的耦合关系,在以往的研究中还未见到,因而有必要在今后的研究中加以重视。我国夏季降水和海温的耦合关系,还表现在长江中下游地区的降水异常与太平洋和大西洋海温异常的显著相关上。当南海和黑潮区域以及相邻的热带西太平洋海区海温为正异常时,热带和北大西洋海温也为正异常;而热带中、东太平洋海温为负异常时,长江中下游地区往往偏涝;反之,该地区则偏旱。     

EFFECT OF WINTER MONSOON ON SUMMER MONSOON THROUGH AIR-SEA INTERACTION*

In this paper the relationships between the sea surface temperature (SST) of Xisha and that in the northern Indian and northern Pacific Oceans,the geopotential height at 500 hPa level of the Northern Hemisphere,and rainfall in China are studied statistically using data in the period of 1961-1992.Results show that in winter,the interannual variation in SST of Xisha describes that for a large oceanic region off the East Asia coast,and is closely related to the activity of East Asia winter monsoon.On the other hand,there exist very high values of auto-correlation of Xisha SST anomaly from December through the following July,but the anomalous condition is hardly correlated to that in the preceding autumn.The winter monsoon related anomalous SST condition in Xisha has a strong tendency to persist through the succeeding summer monsoon season with the same sign.In addition,correlation maps of monthly mean rainfall in China with respect to Xisha SST of the same month show positive correlations with confidence level above 95% to the east of 110°E and to the south of Changjiang (Yangtze) River during the months of October through April;the region becomes smaller in May and changes correlation sign in June;the positive correlation region is located in the middle and lower reaches of Changjiang River from July to September.The air-sea interaction plays an important role in these processes.     

Interannual winter rainfall variability in SW South Africa and large scale ocean–atmosphere interactions

Summary The Southwestern Cape (SWC) region of South Africa is characterized by winter rainfall mainly via cold fronts and by substantial interannual variability. Evidence is presented that interannual variability in SWC winter rainfall is related to sea-surface temperature (SST) and sea-ice anomalies in the central South Atlantic and adjoining Southern Ocean and to large scale ocean–atmosphere interaction in this region. During wet winters, the jet is strengthened just upstream of the SWC and significant cyclonic anomalies extend from the SW Atlantic over the region. SST tends to be anomalously warm (cool) in the SW Atlantic and SE Atlantic (central South Atlantic) and sea-ice extent increased in the central South Atlantic sector of the Southern Ocean. These patterns favor increased cyclogenesis upstream, a more northward track of midlatitude depressions, local intensification near the SWC and enhanced rainfall. Roughly the reverse patterns occur during dry winters. Some preliminary results from atmospheric GCM experiments are presented which help support these findings. Received November 9, 2001 Revised December 28, 2001