海洋性大陆西部夏季降水异常:独立和联系于IOD的模态
投稿时间: 2016-11-26  最后修改时间: 2017-01-22  点此下载全文
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作者单位E-mail
许琪 南京信息工程大学 xqaaron@163.com 
管兆勇 南京信息工程大学 guanzy@nuist.edu.cn 
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:摘要:受到诸多气候因素的影响,海洋性大陆(Maritime Continent, MC)降水异常表现出显著的区域性特征。利用1979-2013年的NCEP/NCAR、GPCP和GODAS月平均再分析资料,通过回归分析等方法,研究了MC地区偏印度洋一侧降水的区域性特征及其与热带、东亚地区环流变化的联系。结果表明:海洋性大陆西部,爪洼岛以西洋面(A区)与苏门答腊海以西赤道洋面(B区)降水存在一定程度相关的同时,还存在较大差异。两个区域夏季降水正异常时,来自赤道印度洋、赤道太平洋、南海及孟加拉湾地区的水汽输送偏强。A区降水与IOD现象密切相关,B区降水则与季风活动的变化联系密切。A区降水异常偏多时,混合层的暖海水向A区汇合,A区的海温异常偏高得以维持,对流层低层在A区及其西南部出现气旋性环流,产生气流辐合,有利于上升运动的发生,降水增多。当B区降水正异常时,对流层低层环流与A区降水正异常时较为相似,但气旋性环流范围偏小,偏西。B区的暖海温的维持主要与海洋中的垂直运动有关。这些结果有利于深刻认识MC区域气候变动特征及亚洲夏季风环流异常的成因。
中文关键词:海洋性大陆、降水异常、IOD、海温异常、北半球夏季
 
Summer precipitation anomaly in the western Maritime Continent: Modes independent and dependent of the IOD
Abstract:Abstract: Influenced by many climatic factors, the precipitation anomaly over Maritime Continent (MC) shows its strong regional features. Based on the NCEP/NCAR, GPCP and GODAS monthly mean reanalysis data from 1979 to 2013, we have investigated the regional characteristics of precipitation in the Indian Ocean side of MC and the relationships between different precipitation patterns with variations of the East Asian monsoon and tropical circulation using regression and other statistical methods. The results show that one oceanic area to the west of Java Island (Box-A) and the other part of equatorial Indian Ocean to the west of Sumatra (Box-B) are two key regions where the precipitation varies inter-annually with larger variance in the west of the Maritime Continent. It is found there are large differences of the rainfall variation in Box-A from that in Box-B although the rainfall variations are significantly correlated between these two key regions. When the summer precipitation is abnormally high in these two areas, the water vapor from the equatorial Indian Ocean, the equatorial Pacific, the South China Sea and the Bay of Bengal is strong. However, precipitation in Box-A is closely related to the IOD mode while the precipitation in Box-B has better relationship with monsoon activities. When the precipitation anomalies in Box-A is positive, the warm sea water in the mixed layer converges to Box-A to sustain the high than normal SST in this area, facilitating an anomalous cyclonic circulation over Box-A and its southwestern side to the Box-A in the lower troposphere. This warmer SSTA along with the cyclonic circulation are responsible for the anomalous upward motion and more precipitation there. When the precipitation is abnormally high over Box-B, the anomalous circulation looks similar to that in Box-A, but little weaker and more westward. The warmer SST in Box-B is mainly related to the upwelling anomalies in the ocean. All the results are helpful for our better understanding of the mechanisms of variations of both regional climate in MC and the Asian summer monsoon anomalies.
keywords:Maritime continent, precipitation anomaly, Indian Ocean dipole, SST anomaly, boreal summer
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