全球气候变暖背景下四川地区夜雨的变化特征

Night precipitation variation in Sichuan under global warming

采用趋势分析、Mann-Kendall突变检验、小波分析等方法,针对四川省39个测站1970—2010年逐日降水资料,分析四川地区近40年昼夜降水量、夜雨率、夜晚大降水日数的时空分布特征和变化规律。结果表明:四川地区昼夜降水量分布均呈"东多西少"特点,但川西高原降水量呈增多趋势,四川盆地呈减少趋势,且夜晚降水量的气候变化倾向率高于白天;夜晚年降水量变化存在准7年周期和准4年周期,白天年降水量变化则存在准11年周期、准5年周期和准3年周期;四川地区大部年夜雨率超过60%,其中乐山、雅安达到72%;四川地区夜雨率变化周期为准12年和准3年,但无明显突变现象;夜晚年大降水日数存在准8年周期和准4年周期,也无明显突变;甘孜东南部、雅安的夜晚大降水日数呈明显增多趋势,而阿坝等地夜晚的大降水日数呈减少趋势;四川地区夏季夜晚降水量与东亚夏季风指数呈反相关关系,这在雅安、广元、达州、甘孜、阿坝西南部等地尤为显著。

The precipitation variation and precipitation periodicity were investigated by means of trend analysis,Mann-Kendall method and Morlet wavelet analysis based on the daily precipitation data of 39 stations in Sichuan from 1970 to 2010.The results show that the spatial distribution of annual precipitation variation in Sichuan decreases from east to west.Precipitation in Western Sichuan Plateau increases while Sichuan Basin decreases.The climate inclination rate at night is higher than that at daytime.Pre-cipitation cycles of night are 7 years and 4 years while those of day are 11 years,5 years,and 3 years.The cycles of day above heavy rainfall are 8 years and 4 years.There is no significant mutation in Sichuan for day above heavy rainfall.The variation trend of heavy rain days shows that the days above heavy rainfall increase significantly in the southeast of Ganzi,Yaan while de-crease in Aba.Precipitation of night in Sichuan has a negative significantly correlation with EASMI over the northwest and east of Sichuan province.