杭州市降水特征及极端降水趋势预估

Precipitation Characteristics and Projection of Extreme Precipitation Trend in Hangzhou City

利用国家气候观象台杭州站百年降水观测数据和CMIP5模式模拟预估数据,分析了杭州市降水长期变化特征,采用累积概率分布函数转换方式(CDF-T),降尺度预估了未来气候情景下杭州极端降水发生趋势。结果表明:杭州市年降水量在百年时序(1907—2015年)上无显著性增加或减小趋势,1980年后春季降水明显下降,下降速率约32.1mm·(10a)^(-1),冬季降水显著增加,增加速率约35.4mm·(10a)^(-1)。1988—2015年的3和6h及日降水的各重现期降水量均较1961—1987年有所增大,1961—1987年的100年一遇日最大降水已演变为1988—2015年的50年一遇甚至是20年一遇。CMIP5模式降水的降尺度分析表明,2020—2039年杭州市日极端降水强度将可能会进一步加强,2020—2039年日降水的R95值和R99p值均较现气候期(1981—2010年)有所提高,超R95p和超R99p的极端降水发生日数分别为11.08和2.24d·a^(-1),分别较现气候期平均值增加了3.52和0.69d·a^(-1)。

Based on the observational precipitation data from Hangzhou Climate Observatory and the simu- lated precipitation data of the global climate model CMIPS, the long-term trends of precipitation variation in Hangzhou City are investigated. Moreover, the risks of extreme precipitation in Hangzhou City under future climate scenarios are estimated by using a downscaling method that adopts the cumulative distribu- tion function transform （CDF-T）. The results show that there is no significantly increasing or decreasing trend in centennial precipitation series （1907--2015） at Hangzhou Climate Observatory, but the precipita- tion in spring obviously decreases with a rate of 32.1 mm·（10 a）-1 and the winter precipitation signifi- cantly increases with a rate of 35.4 mm · （10 a）-1 during 1980-2015. The extreme precipitation in Hang- zhou City has been intensifying, which can be interpreted by that the maximum values of 3 h, 6 h and dailyprecipitation have been increased and the return periods of extreme precipitation have been shortened. Du- ring the period from 1988 to 2015, the values of the 3 h, 6 h and daily precipitation of each return periods are higher than that of the period from 1961 to 1987. An extreme daily precipitation whose probability is once in 100 years during 1961--1987 has become an event with probability once in 50 years or once in 20 years during 1988-2015. The CDF-T downscaling analysis of simulated precipitation of the CMIP5 models indicates that the occurrence probability of extreme precipitation in Hangzhou City during 2020- 2039 might increase under all of the RCPs future climate scenarios. In the period from 2020 to 2039, the occur- rence probability of the extreme precipitation over R95p and R99p in Hangzhou City will be 11.08 d ·a- 1 and 2.24 d · a-1 respectively. Compared with the average values of current climate, the occurrence proba- bility of the over R95p and R99p is increased by 3.52 d · a-1 and 0.69 d · a-1 , respectively.