亚洲季风区大气热源和水汽汇的季节内变化Ⅱ. 水汽汇的季节内变化

INTRASEASONAL VARIATIONS OF THE ATMOSPHERIC HEAT SOURCES AND MOISTURE SINKS OVER ASIAN MONSOON REGION PART Ⅱ:MOISTURE SINKS

关键词:  大气水汽汇  季风  季节内变化

Key words:  Atmospheric moisture sink  Monsoon  Intraseasonal variation

摘要:

用ECMWF1980-1983年资料探讨了亚洲季风区水汽汇季节内变化的标准差分布、空间型及传播,并讨论了水汽汇与热源(本文第I部分)季节内变化特点的异同。结果表明:一方面,季节内时间尺度上水汽汇的变化特征与热源比较一致(尤其是在夏季),变化显着区主要位于季风活跃区及其附近地区,与季风雨带的位置极为接近,且夏季陆地上清楚,冬季海洋上明显;EOF分析的主要空间型反映了印缅地区、中国东部及沿海、西太平洋地区水汽汇变化存在一定的联系,相应的时间系数以30-60天振荡为主。另一方面,在冬半年两者间存在明显差异,这种差异反映了感热、蒸发或辐射变化的作用。夏半年水汽汇30-60天变化的传播在东亚和南亚两个季风区有不同的特点,这在一定程度上反映了两个季风系统的相对独立性。

Abstract:

Using the ECMWF data of 1980 to 1983, the intraseasonal component of the variation of the atmospheric moisture sink< Q₂ >(Vertically integrated) over Asian monsoon region is examined, including the standard deviation, EOF patterns and the propagation of the oscillation. The results show, consistant with< Q₁ > especially in summer, that the large intraseasonal variance of < Q₂ >is mainly confined over the active monsoon region of Asia and surround areas, and that the main EOF patterns indicate as well the relationship of intraseasonal oscillations between regions of India-Burma, the coast of East China and the western Pacific while the corresponding the EOF time coefficients have that their dominant period ranging from 3O to 60 days. On the other hand, between < Q₂ >and < Q₁ >there exist differences in the features of the intraseasonal variation between < Q₁ >and < Q₂ >especially in winter. The propagational difference of 30-60 day fluctuation over regions of East Asia and South Asia in summer was Found by means of lagged correlation analysis. To some extent, this regional difference indicates the difference of the two Asian monsoon systems.