甘肃省近40a汛期无雨日数异常的气候特征分析

ANALYSIS ON THE CHARACTERISTIC OF THE RAINLESS DAYS ANOMALY IN FLOOD SEASON IN GANSU PROVINCE OF CHINA

本文利用1960～2001年甘肃省59个气象站的逐日降水资料,统计出汛期(4～9月)各站无雨日数,分析了甘肃汛期无雨日数的基本时空分布特征,并对其标准化后进行经验正交展开(EOF)和旋转经验正交展开(REOF),研究其异常的空间结构及时间演变规律。结果表明:甘肃省汛期无雨日数自东南向西北呈台阶状增加,甘肃汛期无雨日数异常在空间上表现为一致的增多或减少。旋转载荷向量场(RVL)反映出5个无雨日数异常型。旋转主分量(RPC)揭示了42a甘肃汛期无雨日数的时间演变特征,即甘肃中部、陇南、甘南区无雨日数经历了少～多～少的过程,河西为多～少～多的反抛物线型,气候向更干旱化发展,而陇东无雨日数增加趋势较为明显。

With EOF and REOF the spatial anomaly features and time evolution rules for the rainless days in flood season in Gansu province are studied in detail by using the daily precipitation data for the period of 1960-2001 from 59 observational stations in the area of Gansu province. The results show that spatial rainless days anomaly is consistent in whole Gansu province(LV), and the rotated loading vector fields(RLV) represent 5 main anomaly regions. The rotated principal component(RPC) reveals the temporal evolution features of rainless days in flood season.