东亚冬季风异常的空间结构及与海陆热力差异的联系

Spatial Structure of East Asian Winter Monsoon and Its Relationship with Sea-Land Thermal Contrast

摘要:

对NCEP/NCAR再分析资料采用经验正交函数和奇异谱分析方法研究东亚冬季风异常的空间结构和时间变率,在进行相关分析的基础上用奇异值分解方法研究东亚冬季风异常与海陆热力差异的联系。分析结果表明:在东亚季风区内冬季风异常有明显的地理差异,根据经向风的气候平均图及均方差图上极值中心的位置、形态,确定三个区域。WM1、WM2、WM3区为东亚冬季风的三个子系统,分别位于南海、东海、日本海上。三个子系统强度的年际、年代际变率都不同。近40aWM3区冬季风呈减弱趋势,而WM1、WM2区冬季风没有明显的减弱趋势。不同地区海陆热力差异影响不同子系统的强度,WM1、WM2区冬季风与热带西太平洋海温相关紧密,WM3区冬季风与高纬度海陆热力差异相关密切。

关键词:东亚冬季风;变率;空间结构;海陆热力差异

Abstract:

Using NCEP/NCAR reanalysis data,spatial structure and time variability of East Asian winter monsoon are discussed and relationship between East Asian winter monsoon and land-sea thermal contrast is investigated with the means of EOF,SVD and SSA.Results show that there is spatial distribution in East Asian when monsoon is anomalous.Three subsystems(WM1?WM2?WM3)are defined according to the situation and pattern of extremum centers of climate mean and the variance of meridional wind.Interannual and interdecadal variations of winter monsoon in WM1?WM2 are different from WM3.Winter monsoon in WM3 is becoming weaker in recent 40 years and the monsoons of WM1 and WM2 have a vague strengthening trend.Land-sea thermal contrast affects monsoon of different subsystems.Monsoon anomaly of subsystems WM1 and WM2 are well relative to temperature of tropical west Pacific.Monsoon anomaly of subsystem WM3 bears a close relation to the thermal contrast in high latitude.

Key words:east Asian winter monsoon;variability;spatial structure;land-sea thermal contrast