冬季北太平洋海温主模态年代际调整及其对东亚季风的影响

发布时间：2018-01-14 02:14

本文关键词：冬季北太平洋海温主模态年代际调整及其对东亚季风的影响　出处：《中国气象科学研究院》2015年硕士论文　论文类型：学位论文

【摘要】：本文利用中国160站观测降水、NECP/NACR大气再分析、Hadley环流中心海温等资料(HadISST1),采用EOF和时间位相EOF(T-EOF)等统计方法并利用ECHAM5大气环流模式,分析了冬季北太平洋海温PDO(Pacific Decadal Oscillation)和NPGO(North Pacific Grye Oscillation)主模态在1990之后发生调整的可能原因,探讨了冬季PDO和NPGO型海温模态对同期我国华南降水的可能影响和途径。主要结论如下:(1)冬季北太平洋海温主导模态由PDO调整为NPGO模态可能成因来自海洋和大气两方面。1990年前后,北太平洋中部(28-36?N,152?-178?W)与北部(44?-49?N,151?-177?W)海温异常关系由正相关演变成负相关,这是北太平洋主导模态发生调整的海洋内部原因,而冬季北太平洋涛动(NPO)在1990年之后的显著增强是海温主导模态调整的重要大气强迫;(2)冬季PDO和NPGO与北半球大气之间表现出明显的耦合。其中,与PDO耦合的大气异常表现为阿留申(AL)低压加强和30°N的850hPa显著的西风增强,而与NPGO耦合的大气模态表现为NPO正位相和40°N的850hPa显著西风异常,而对流层西风中心位置南北变化对我国冬季华南地区降水有重要影响,当NPGO正位相时冬季华南降水偏少;(3)数值模拟表明,在PDO型海-气耦合模态中副热带和热带东太平洋海温异常对维持大气AL效果相同,但是副热带太平洋的影响更重要。NPGO型海-气耦合模态中,赤道中太平洋海温对大气的影响更为重要。进一步分析发现,冬季华南地区降水在1990年之后的持续偏多与NPGO负位相增强的关系更加密切。
[Abstract]:In this paper, we use the precipitation observed at 160 stations in China (HadISST1) to analyze the sea surface temperature (SST) of Hadley Circulation Center in the NEP / NACR atmosphere reanalysis. The statistical methods such as EOF and time phase EOF- EOF) are used and the ECHAM5 atmospheric circulation model is used. In this paper, the PDO(Pacific Decadal scscillationof the North Pacific Ocean in winter is analyzed. North Pacific Grye orchestration) the possible cause of the adjustment of the main mode after 1990. The possible effects and approaches of winter PDO and NPGO SST modes on precipitation in South China during the same period are discussed. The main conclusions are as follows: 1). In winter, the dominant mode of sea surface temperature in the North Pacific Ocean is adjusted from PDO to NPGO mode, which may be caused by both ocean and atmosphere. About 1990. North Pacific Central China 28-36? N,152? -178? W) and North China 44? -49? N,151? -177? The relationship of sea surface temperature anomaly evolves from positive correlation to negative correlation, which is the internal reason for the adjustment of dominant modes in the North Pacific Ocean. The significant enhancement of NPO in winter after 1990 is an important atmospheric forcing for SST modal adjustment. (2) in winter, PDO and NPGO show obvious coupling with the atmosphere of the Northern Hemisphere. The atmospheric anomalies coupled with PDO are the enhancement of the low pressure of Aleutian (ALL) and the significant increase of the westerly wind at 850 HPA at 30 掳N. The atmospheric modes coupled with NPGO are NPO positive phase and 850hPa westerly anomaly at 40 掳N. The variation of the westerly center of the troposphere has an important influence on the precipitation in South China in winter. When the NPGO is positive, the precipitation in South China in winter is less. Numerical simulation shows that the subtropical and tropical eastern Pacific SST anomalies have the same effect on the maintenance of atmospheric AL in the PDO coupled mode. However, the influence of the subtropical Pacific is more important. In the coupled ocean-atmosphere mode of NPGO, the influence of SST in the central equatorial Pacific is more important. The continuous precipitation in South China after 1990 is more closely related to the enhancement of the negative phase of NPGO.
【学位授予单位】：中国气象科学研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P731.11;P461.2

【参考文献】