【摘要】 在分析华西秋雨气候特征的基础上,设计了综合考虑秋季降水量和降水日数的秋雨指数,并进行了EOF和REOF分解以及秋雨主要影响因素分析。结果表明:第一模态反映了长江中上游以北地区与以南地区降水相反的形势,第二模态反映了华西降水的一致性;REOF将华西秋雨可分为6个气候区。华西秋雨的变化趋势表明,1960年代到1970年代初期、1980年代初期为相对多秋雨期,1970年代中后期、1980年代中后期到20世纪末华西秋雨相对较少。21世纪开始又出现了较明显的华西秋雨现象。西太平洋副热带高压、印缅槽、贝加尔湖低槽是华西秋雨的主要影响系统,当贝加尔湖、印缅槽深且副热带高压强时,有利于华西多秋雨;反之,则秋雨不明显。更多还原

【Abstract】 On the basis of analying the climatic characterstics of autumn rain over Southwest China, the autumn rain index was designed by using the autumn precipitation and rain day numbers, meanwhile, the decompositions of EOF and REOF technique were carried out, and the main effective factors about autumn rain were analyzed. The results showed that the first mode indicates the precipitation trend to the north and to the south over the mid-and-upper reaches of Changjiang River is just oposite. The second load eigenvector fields reflectes the consistency of precipitation over Southwest China. The six climatic zones of autumn rain over Southwest China were respectively divided by REOF technique. The trend of climatic change indicated that there is more rain comparatively over Southwest China in autumn in the periods of from 1960′s to early 1970′s and 1980′s, and for less rain in the periods of mid-and-late 1970′s, from middle 1980′s to late 1990′s, however the autumn rain appeared obviouslyin early 21^st centurytoo. Western Pacific subtropical high, trough located at India and Burma, and Baikal trough were the main influence systems of autumn rain over southwest China. If the Baikal trough and India-Burma trough were well-developed and west Pacific subtropical high were strengthened, which would be favorable for more rain over Southwest China in autumn, on the contrary, if the condition was overturned, and then which would resulted in rainless.更多还原