热带西北太平洋10～30d振荡对南海夏季风影响  

Impact of 10-30-day Oscillation Intensity over the Tropical Northwest Pacific Ocean on the South China Sea Summer Monsoon

作　　者：李春晖[1] 刘燕[2] 李霞[2] 潘蔚娟 

机构地区：[1]中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室,广州510080 [2]广州中心气象台,广州510080 [3]广东省广州市气候中心,广州510080

出　　处：《应用气象学报》2016年第3期293-302,共10页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(41205069;41375095;41505067;41575043);国家重点基础研究发展计划(2014CB953901);广东省科技计划重点项目(2012A030200006)

摘　　要：采用1958—2011年NCEP/NCAR再分析资料以及ERSST海温资料,分析热带西太平洋夏季对流10~30 d振荡对南海夏季风的影响。在年际变化尺度上,热带西北太平洋夏季10~30 d振荡强度指数（TWPI）与南海夏季风强度有很好的正相关关系。在TWPI增强年份,海温主要呈El Ni？o分布,南海周边区域增强的异常西风产生强的正涡度切变,导致异常气旋性环流,为季风槽的增强提供了热量和水汽,从而增强南海夏季风强度。反之,在TWPI减弱年份,海温主要呈La Ni？a分布,南海夏季风强度减弱。在不同的年代际背景下,垂直切变和水汽-对流的总体变化是影响TWPI总体变化的重要因子,但不能影响南海夏季风强度的总体变化。海陆热力对比的总体变化是导致南海夏季风强度总体变化的主要影响因素。Based on the NCEP reanalysis data and ERSST sea surface temperature（SST） data, using statistical methods, 10--30-day significant sub-seasonal variability periods are extracted from the summer （Jun-- Aug） convective in the tropical western Pacific, and these oscillations have different effects on the South China Sea summer monsoon intensity at different scales. At inter-annual time scale, a positive significant correlation is found between the intensity variation of 10--30-day oscillation over the tropical northwest Pacific Ocean regions （TWPI）, and the correlation coefficient is 0. 635. Influences of TWPI on the South China Sea summer monsoon intensity are mainly regulated by ENSO. Because of the asymmetric response of the lower troposphere Northwest Pacific atmospheric circulation to ENSO, TWPI is much more signi{i- cant in E1 Nifio developing years than in La Nifia years. During strong TWPI years, the SST anomalies are E1 Nifio pattern, which induces anomalously enhanced westerly in the South China Sea, the Philippines and the tropical northwest Pacific Ocean. The westerly anomalies generate strong positive vorticity shear, re- sulting in abnormal cyclonic circulation, and enhance TWPI and summer monsoon intensity through the wind-evaporation feedback mechanism. On the contrary, in La Nifia years, the anticyclonic anomaly circu- lation result in TWPI weakening and the monsoon strength weakening. Under different inter-decadal back- grounds, TWPI does not show a significant change in the decadal trend, mainly slightly weaker （1958-- 1976）, slightly stronger （1977--1993） and slightly weaker （1994--2011） change. The trend of the sum- mer monsoon intensity inter-decadal changes are more obvious, namely, much stronger, slightly weaker and much weaker. The overall change of vertical shear and water vapor-convection are consistent with TWPI, but are not consistent with the summer monsoon. Vertical shear of wind field and water vapor-con- vection play important roles on the inter-decadal variatio

关 键 词：热带西北太平洋 10~30 d振荡 南海夏季风 强度 

分 类 号：P461.2[天文地球—大气科学及气象学] P425.42