| 近百年中国东部夏季降水年代际变化特征及其原因 |
| |
| 引用本文： | 吕俊梅,祝从文,琚建华,林祥.近百年中国东部夏季降水年代际变化特征及其原因[J].大气科学,2014,38(4):782-794. |
| |
| 作者姓名： | 吕俊梅 祝从文 琚建华 林祥 |
| |
| 作者单位： | 1.中国气象科学研究院, 北京 100081 |
| |
| 基金项目： | 中国科学院战略性先导科技专项子课题XDA05090408，国家重点基础研究发展计划（973计划）项目2012CB417205，公益性行业（气象）科研专项项目GYHY200906017，中国气象科学研究院基本科研业务费项目2010Z001、2013Z002，人力资源和社会保障部留学回国人员择优资助项目 |
| |
| 摘 要： | 本文利用测站降水观测资料分析过去一百多年中国东部华北、长江流域以及华南夏季降水的年代际变化特征发现，尽管这三个地区的夏季降水具有不同的年代际转折时期，但是均同时在1910年代初期、1920年代初期、1940年代中期、1960年代中期、1970年代末期以及1990年代初期发生了跃变。近一百年间不同年代际时期东部夏季降水的分布型主要以南正北负或者南负北正的偶极型为主，并且无论是偶极型分布还是三极型分布，两个相邻年代际时期中国东部降水分布型发生完全反向变化的概率较高（60%）。此外，夏季的PDO、冬季的AO以及春季的北极海冰也同时在1920年代末期、1940年代中期、1970年代末期以及1990年代中期左右发生了跃变，这几次跃变时期与中国东部三个不同地区夏季降水发生跃变的时期一致，表现出近百年来太平洋年代振荡（PDO）、北极涛动（AO）以及北极海冰这三个因子对中国东部夏季降水年代际变化的协同作用。在年代际时间尺度上，夏季的PDO与华北夏季降水显著负相关。PDO的年代际变化能够在500 hPa位势高度场中激发出太平洋—日本（PJ）型年代际遥相关波列；同时在850 hPa风场中激发出类似于影响华北夏季降水年代际变化的大气环流型，从而影响华北降水的年代际变化。冬半年的AO与长江流域夏季降水存在显著正相关关系。冬季到春季正位相的AO导致亚洲大陆南部处于湿冷状态，土壤湿度的记忆性可将这种状态延续到夏季。因此，夏季海陆热力对比减弱，东亚夏季风发生年代际减弱，相应地长江流域的降水年代际增多。春季北极海冰与华南夏季降水显著负相关，北极海冰的年代际异常能在500 hPa位势高度场中激发出与静止Rossby波异常传播相联系的欧亚—华南年代际遥相关波列，从而影响华南降水的年代际变化。
|
| 关 键 词： | 中国东部 夏季降水 年代际变化 |
| 收稿时间： | 2013/7/28 0:00:00 |
| 修稿时间： | 1/8/2014 12:00:00 AM |
Interdecadal Variability in Summer Precipitation over East China during the Past 100 Years and Its Possible Causes |
| |
| L&#; Junmei,ZHU Congwen,JU Jianhua and LIN Xiang.Interdecadal Variability in Summer Precipitation over East China during the Past 100 Years and Its Possible Causes[J].Chinese Journal of Atmospheric Sciences,2014,38(4):782-794. |
| |
| Authors: | L&#; Junmei ZHU Congwen JU Jianhua and LIN Xiang |
| |
| Institution: | 1.Chinese Academy of Meteorological Sciences, Beijing 1000812.Yunnan Provincial Meteorological Service, Kunming 650034 |
| |
| Abstract: | In this paper, the interdecadal variations of rainfall over North China, the Yangtze River valley, and South China during the past 100 years are examined using weather station data. The results show that the rainfall over these three regions underwent simultaneous shifts in the early 1910 s, the early 1920s, the middle 1940 s, the middle 1960s, the late 1970 s, and the early 1990 s, although there are different interdecadal shifting periods. During the past 100 years the distribution patterns of summer rainfall over eastern China are primarily characterized by dipoles, such as "positive south and negative north" or "positive north and negative south" in different interdecadal periods. Furthermore, the probability of the totally reverse distribution patterns during two adjacent interdecadal periods is higher (60%) whether they are dipolar or tripolar. In addition, summer Pacific Decadal Oscillation (PDO), winter Arctic Oscillation (AO), and spring arctic sea ice also showed synchronous shifts around the late 1920s, the middle 1940s, the late 1970s, and the middle 1990s, consistent with the shifting periods of summer precipitation over three regions of eastern China, suggesting that PDO, AO, and arctic sea ice have played a synergetic role in the interdecadal variation of summer rainfall over eastern China during the past 100 years.At interdecadal time scales, PDO in summer is significantly negatively correlated with summer rainfall in North China. The interdecadal variability of PDO may generate interdecadal wave trains of Pacific-Japan (PJ) interconnection pattern at 500-hPa geopotential height and atmospheric circulation in the 850-hPa wind field, which is similar to that affecting the interdecadal variation of summer rainfall over North China. Consequently, summer rainfall over North China showed interdecadal variation. The AO in wintertime is significantly positively correlated with summer rainfall over the Yangtze River valley. When AO enters its positive interdecadal phase from winter to spring, it causes an increase of precipitation and a decrease in temperature over the southern Eurasian continent. The cold and wet state over the southern Eurasian continent persists from winter to summer because of the memory of soil humidity. It causes the weakening of sea-land contrast in summer. As a result, the East Asian summer monsoon experiences interdecadal weakening. Correspondingly, the rainfall over the Yangtze River valley shows interdecadal increase. Spring Arctic sea ice is significantly negatively correlated with summer rainfall over South China. Interdecadal variation in Arctic sea ice can generate interdecadal wave trains of the Eurasia-South China interconnection pattern associated with the anomalous propagation of stationary Rossby waves at 500-hPa geopotential height, which affects the interdecadal variation in rainfall over South China. |
| |
| Keywords: | East China Summer precipitation Interdecadal variation |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《大气科学》浏览原始摘要信息 |
| 点击此处可从《大气科学》下载免费的PDF全文 |
|
