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：

根据浙江省1961 ～ 2010 年逐日降水量资料，在对不同等级降水日数进行趋势分析的基础上，
运用Mann － Kendall 检验、等值线分布等方法对显著降水事件进行时空分布特征的研究，探讨浙江省
不同等级降水日数的时间演变趋势和空间分布特征。结果表明: 近50 a 来，浙江省总降水日数呈明
显的下降趋势，相当于每10 a 减少4． 82 d，其中小雨日数占总雨日的73． 00%。在时间变化上，总雨
日和小雨日均在1980 年代中后期发生突变，转为急剧下降趋势，且小雨日的减少趋势略超前于总雨
日。在空间分布上，年降水日数和小雨日数的空间分布基本一致，在台州、宁波出现了高值中心，低值
区域主要分布在浙江东北部，而浙西南地区变化平缓; 空间趋势分布表现为全省一致的减少趋势，东
部沿海下降趋势显著，而内陆地区下降缓慢。浙江省年雨量及其气候倾向率的分布，均表现出较明显
的“东—西”向差异，和地形高低有一定关系。年雨量整体表现为增加趋势。以上研究说明，在近50
a 来，浙江省发生极端天气事件的概率明显增加，干旱或洪涝的趋势或风险加大。

关键词: 降水日数, Mann － Kendall 检验, 降水等级