Abstract:

Based on the daily precipitation data from 1961 to 2010 in Zhejiang Province，and on the basis of trend analysis on different levels rainfall days，the Mann － Kendall test and contour distribution method were used to analyze the significant precipitation events，in order to explore the temporal evolution laws and spatial distribution characteristics of different levels precipitation days in Zhejiang Province． The results show that in recent 50 years，the total rainfall days in Zhejiang presented a significant decreasing trend with the rate of 4． 82 d /10 a，and the light rainfall days accounted for 73． 00% of total precipitation days． Both the total rainfall days and light rainfall days had an abrupt change into a sharp downward trend in the middle and late 1980s，and the decreasing trend of light rainfall days was a little ahead of that of total rainfall days． For spatial distribution，both annual total rainfall days and the light rainfall days were basically same with high － value centers in Taizhou and Ningbo，and low － value areas in the northeast and gentle change in the southwest of Zhejiang． The spatial distribution showed a consistent decreasing trend in the whole province，among which the east coast had a significant downward trend，while inland areas had a slow decline． The distribution of annual precipitation and its climate trend rate presented obvious characteristics of“East －West”，which was related to topography of Zhejiang． Annual precipitation showed an overall increasing trend． From the results described above，the probability of extreme weather events increased significantly in the past 50 years in Zhejiang，and the risk of drought or floods increased．

Key words: climatology, precipitation days, Mann － kendall test;

摘要：

利用甘肃民勤自动气象站观测的2004 ～ 2006 年夏季的5 min 一次的气温与沙尘PM10浓度资料，通过将数据分为实验组与对照组，研究了气温与沙尘天气之间的统计关系。个例显示，气温与沙尘PM10浓度之间存在降温、升温和混合型3 种对应关系。实验组统计分析表明，气温及其变化( 每5min 间隔气温变化绝对值和每24 h 间隔气温变化绝对值) 与沙尘PM10浓度及其变化呈现出非常显著的正相关关系; 沙尘暴天气下日平均气温变化与相应沙尘PM10浓度变化呈显著负相关。对照组结果表明，实验组统计关系是非常显著的。

关键词: 气温, 沙尘PM10浓度, 统计关系