2007年夏季淮河流域洪涝与亚洲地区大气低频振荡的关系

摘要

利用NCEP/NCAR再分析资料和我国地面观测站的逐日降水资料,研究了2007年夏季淮河流域洪涝与亚洲地区大气低频振荡的联系,通过分析研究表明:2007年夏季淮河流域降水低频振荡的主要周期是30～70天,该低频序列的方差大约占了总方差的47%;在降水低频振荡的位相5～8(1～4),亚洲季风区从阿拉伯海北部经孟加拉湾到我国南海地区,以及我国淮河流域经渤海到日本地区主要受低频热源(热汇)的控制;并且在极大降水位相7,我国东部地区(10°N～45°N,110°E～120°E),从北到南,低频分量的分布呈负正相间的低频热汇、热源、热汇、热源形式(位相3则呈相反的分布形式);在位相5～8(1～4),亚洲季风区低频分量的分布有利于(不利于)气流向淮河流域汇合并形成辐合上升;受低频环流变化的影响,在位相5～8,大量的水汽被输送到淮河流域,辐合上升形成降水;相反,在位相1～4,来自西太平洋上的水汽在该地区辐散,不利于降水的发生.%Floods and droughts often take place in the Changjiang-Huaihe basin. In the summer of 2007, the severe flood occurred again in the Huaihe River basin. In order to investigate the cause, using the NCEP/NCAR reanalysis data and observed daily rainfall from gauge stations, association of the atmospheric low-frequency oscillation (LFO) over Asia with the severe flood in the Huaihe River basin in the summer of 2007 has been studied in this paper. The result shows that: the low-frequency oscillation of rainfall over the Huaihe River basin in the summer of 2007 was mainly controlled by the 30-70-day oscillation, the variance of this time series can account for about 47% of the to-tal variance, thereby, the rainfall 30-70-day low-frequency oscillation plays an important role in the summer flood of 2007; during the period from phases 5 to 8 (1 to 4) of the rainfall low-frequency oscillation (LFO), the Asia monsoon regions from the northern Arabian Sea to the South China Sea across the Bay of Bengal and from the Hua-ihe River basin in China to Japan were mainly controlled by the heating source (sink) of the (Q_1) LFO; at extreme phase 7, the (Q_1) LFO presents the mode distribution of heating sink, heating source, heating sink and heating source from the north to south over eastern China (10°N-45°N, 110°E-120°E), and it is quite the reverse at ex-treme phase 3; from phases 5 to 8 (1 to 4), the distribution of the (Q_1) LFO over the Asia monsoon region is favor-able (unfavorable) for the air flow convergence over the Huaihe River basin and the resulting ascent in this region; because of the change of the circulation low-frequency oscillation (LFO), during the period from phases 5 to 8, more moisture was transported to the Huaihe River basin, convergence and ascent lead to the strong rainfall in this re-gion; reversely, from phases 1 to 4, the divergence of moisture from the westem Pacific took place in the Huaihe River basin, which makes against the rainfall occurring in this region.