中国西北春季降水与太平洋秋季海温的异常特征及其相关分析

A STUDY ON SPRING RAINFALL ANOMALY IN NORTHWEST CHINA AND PACIFIC SSTA FEATURES IN AUTUMN AND THEIR CORRELATIONS

利用中国西北五省 (区 ) 89个测站的 1 960～ 1 994年历年春季 (3～ 5月 )的月、季总降水量和北太平洋 1 0°S～ 50°N ,1 2 0°E～ 80°W范围内的秋季 (9～ 1 1月 )平均海表温度 ,通过EOF ,REOF,SVD等方法 ,对我国西北地区春季降水和前期秋季太平洋海温的异常特性以及两者之间的空间遥相关特征进行了统计分析。结果表明 ,秋季北太平洋SSTA的主要型态是ElNi no/LaNi na分布型 ,其次是副热带太平洋海温东西反相变化的异常型态 ,而最强的异常信号区位于赤道中东太平洋。大范围区域性异常是中国西北地区春季降水的主要空间分布特征。另外还有南北反相和东西反相分布型。西北地区春季降水有 5个主要异常区域 :高原东部边缘区、西北东部区、北疆区、青海高原区、南疆东部及河西区。秋季赤道中东太平洋SSTA与次年春季西北地区区域性降水异常之间有较为明显的正相关关系 ,这种关系在两者的其它空间关系中是第一位的。副热带太平洋海温东正 (负 )西负 (正 )异常空间型态与西北东部的降水负 (正 )异常相对应。另外 ,秋季ElNi no/LaNi na之后的次年 3月和 5月 ,中国西北地区降水普遍以偏多 /偏少为主 ,而 4月份则相反 ,表现为高原东部边缘区的降水异常偏少

With EOF, REOF and SVD, the spatial anomaly features of both the North Pacific SSTA and the spring rainfall in West China and the correlations are studied by using the pricipitation data in spring for the period 1960～1994 from 89 observational stations and the North Pacific sea surface temperature of 286 grid points in the area of 10°S～50°N, 120°E～80°W in autumn. The results show that the first six rotated loading vector fields represent six principal SSTA areas, among which the east equatorial Pacific is the most sensitive signal area. There are five principal spring rainfall anomerly areas in Northwest China: the Eastern Plateau, the eastern part of Northweat China, the Northern Xinjiang, the Qinghai Plateau, the Southern Xinjiang Hexi Corridor. Clear teleconnections really exist between the SSTA in east equatorial Pacific in autumn and the next spring rainfall in Northweat China. When the SSTA is high(low), that is to say, when El Nio(La Nia) appears in autumn, Northwest China is wet(dry) in the next spring. The cases are same in the next March and May. But the wet(dry) center in March is near Xining, Qinghai province; while in May, Pingliang, Gansu province, is the center. In April, the case is contrary with March and May.