淮河流域夏季降水与低纬地区波列结构的关系

Relationship Between the Summer Precipitation in Huai River Basin and the Wavelike Structure in Low Latitude

利用NCEP/NCAR再分析资料,通过合成分析、诊断分析等方法,研究了淮河流域夏季降水异常年份的大尺度环流背景,并且分析了造成这种环流背景的可能原因。得到以下主要结论:在副热带地区,对流层低层存在一个自低纬向高纬传播的波列结构。在多雨年从低纬到高纬呈现"+-+-"相间的波列结构,而少雨年则相反,但是多雨年的波列强度要比少雨年强。利用波活动通量进行诊断发现:在多雨年,菲律宾到南海是明显的波源区,我国淮河流域和印度尼西亚是波汇区;在少雨年,印度尼西亚和我国淮河流域是明显的波源区,南海地区是明显的波汇区。这种波列结构的差异可能与淮河流域降水异常存在密切的联系。大气加热的不同可能是产生波列结构的一个重要原因。研究表明,赤道西太平洋大气热源的变化与我国淮河流域降水有密切的联系。印度尼西亚附近的赤道地区加热强,则淮河多雨;加热较弱,则淮河少雨。诊断分析表明,赤道地区加热强度的变化所产生的Rossby波的不同位相,与我国淮河流域降水的异常有密切的联系。

Using NCEP/NCAR reanalysis data, the synthetic analysis and diagnostic analysis methods, we studied the general circulation background of the abnormal precipitation year in Huai River basin, and analyzed the reason of this general circulation background. The main result showed that： there was a wavelike structure from low latitude to high latitude in bottom troposphere. In rainy year, the wavelike structure showed ＂ ＋ - ＋ - ＂, while it was an opponent structure in dry year. The strength of the wave was stronger in rainy year than that in dry year. By using WAF method to diagnose the wave, we found that in rainy year, the wave sources were located at Philippines-South China Sea, and the wave sinks were located at Huai River and Indonesia. In dry year, the wave sources were located at Huai River and Indonesia, and the wave sink was located at South China Sea. The difference of the wave structure might be an important reason of the abnormal precipitation in Huai River basin in summer. The difference of atmospheric heated between rainy year and dry year may have a close relationship with the generation of the wave. The study also showed that there was close relationship between the precipitation in Huai River basin and the change of the atmosphere heated source in equatorial western Pacific. If the atmosphere heated was strong in equator, the Huai River basin was rainy; or the Huai River basin was dry in summer. The result showed that there was a closely relationship between the difference of the phase of the Rossby wave in sub-tropical which was cased by the change of heated in equatorial western Pacific and the precipitation in Huai River basin in summer.