Abstract:

Based on the data set of snow in east of Qinghai-Tibet Plateau and spring rainfall in Southwest China from 1961/1962 to 2011/2012, the relationship and its temporal variations between snow anomaly in prophase and spring rainfall in Southwest China were analyzed by using methods such as SVD, linear regression analysis, sliding correlation analysis, etc. The results indicate that snow in December and January in east of Qinghai-Tibet Plateau had a good indicative significance to spring rainfall in the Southwest region of Southwest China, and the key region of snow effect located at the southeast of Southern Qinghai Plateau, the north of western Sichuan Plateau and eastern Tibet gorge, with Banma, Shiqu and Dingqing as center, respectively. The main response of spring rainfall was positive, the remarkable regions covered almost the whole Southwest of Southwest China except the northwest and Southwest of Yunnan, especially the juncture region of Sichuan and Yunnan, with Huili and Huaping as center. By using sliding correlation analysis, it was found that the relationship between the prophase snow anomaly in the key area and spring rainfall in the Southwest region of Southwest China always kept positive correlation and its interdecadel change was significant. The period from 1961 to 2011 could be separated into three stages. The first stage from 1961 to 1984 was below 95% confidence level, the second stage from 1985 to 1995 was above 99% confidence level, and the third stage from 1996 to 2011 was between 95% and 99% confidence level. There happened an obvious shift when one stage changed to the next. The interdecadal variation characteristics of the correlationship were close agreement with winter snow in east of Qinghai-Tibet Plateau. In recent years, the correlationship showed the slight decline compared with the previous stage, but still stablely remained above 95% confidence level and could be taken as an important reference for spring rainfall prediction in the Southwest region of Southwest China.

Key words: Qinghai-Tibet Plateau, snow anomaly, Southwest China, spring rainfall

摘要：

选取1961/1962—2011/2012年青藏高原东部积雪和西南地区降水的测站资料，应用奇异值分解方法，结合相关分析和统计检验，分析前期积雪与春季降水的关系及其随时间的变化特征。结果表明：青藏高原东部12月、1月积雪对西南地区西南部春季降水有一定的指示意义；积雪影响关键区位于青藏高原东南缘的青南高原东南部、川西高原西北部和东部的藏东峡谷，分别以班玛、石渠、丁青为中心；春季降水以正响应为主，显著区域覆盖西南地区除滇西北和滇西南以外的整个西南部，以会理、华坪为中心的川滇交界周边地区最为突出；近50 a来，青藏高原东部关键区前期积雪异常与西南地区西南部春季降水间的关系始终保持正相关且表现出显著的年代际变化特征，根据滑动相关结果可分为3个阶段，各阶段之间的过渡均以气候突变的形式完成，1961—1984年相关低于95%置信水平，1985—1995年相关高于99%置信水平，1996—2011年相关介于95%与99%置信水平之间；两者间关系的年代际变化与高原东部冬季积雪的年代际变化基本一致，即高相关阶段对应积雪偏多期，反之亦然；近年来，两者间的相关稳定保持在95%的置信水平以上，较前一阶段略有下降，但仍可作为预测西南地区西南部春季降水的重要参考。

关键词: 青藏高原, 积雪异常, 西南地区, 春季降水