夏季亚洲季风区典型旱涝年大气热源(汇)的变化特征

Characteristics of summer atmospheric heating source/sink LFO over Asian monsoon area in drought/flood years of Yangtze and Huaihe Rivers

使用2001年和2003年NCEP/NCAR再分析资料计算夏季亚洲季风区大气热源(汇),再用BUTTER-WORTH带通滤波器对原始热源(汇)场进行带通滤波,得到2001与2003年夏季30-60天的大气热源(汇)的低频分量,然后分析两年夏季东亚各区域大气热源(汇)及其低频变化特征、传播特征和传播差异,得出以下结论:(1)2001年<Q1>呈连续带状分布;2003年热源中心分布零散且位置显著东移,热源(汇)强度比2001年减弱;(2)2001年和2003年<Q1>低频分量的平均分布有明显差异,且旱年低频分量强度远大于涝年;(3)2001年低频振荡向北传播范围仅到20°N-30°N的华南至江南地区,而2003年低频振荡多数可达30°N以北的江淮流域;(4)2001年低频分量纬向传播均为自西向东,而2003年在6-8月期间自东向西传播,5月和9月则主要由西向东传播。因此,江淮流域典型旱涝年分2001年和2003年在<Q1>低频分量的配置和低频波的传播上存在明显差异,这可能正是导致这两年气候巨大差异的原因之一。

The atmospheric heating source/sink over the Asian monsoon area are calculated by using the NCER-NCAR re-analyses data of 2001-- 2003 . Its 30 - 60 day low-frequency oscillation （LFO） is calculated with the band-pass filter. The differences of the LFO transformative transmittable characteristics between the drought and flood years are studied. The results show that ： （ 1 ） The distribution of （Q1） in 2003 is single and evidently eastward while it distributed cingulately with stronger centers in 2001. （2） The （Q1） LFO distributed reversely in2001 or 2003. and they are evidently stronger in the drought years like 2001. （3） The transformation of （Q） LFO in 2001 did not exceed 30°N while most of them arrive at the Yangtze and Huaihe Rivers in 2003. （4） Then zonal-transformation is from west to east in 2001 and 2003. They transferred as the same in June to August but reverse in May or September. The different precipitation is caused by the different travel and distribution of the OLR-LFO between drought and flood years.