江门高温和降水的概率分布及极端事件重现水平

Distribution of the Probability of High Temperature and Precipitation in Jiangmen and Return Level of Extreme Events

利用1961—2015年江门6个气象观测站逐年最高气温、汛期降水、最大日降水资料,采用线性倾向估计、广义极值分布(GEV)等统计方法,研究了江门年最高气温、汛期降水、最大日降水的概率分布及其极端事件的重现水平。结果表明:1)各站年最高气温概率均属Weibull分布,概率密度峰值对应气温恩平最大、上川岛最小;变化幅度恩平最大、台山最小。较低重现期(20年或以内)时,极端高温事件阈值恩平最高;重现期超过50年时,鹤山最高。2)各站汛期降水概率均属Weibull分布,概率密度峰值对应雨量及变化幅度恩平最大、鹤山最小;不同重现期,恩平极端降水事件阈值均显著高于其它台站,鹤山最低。3)鹤山、恩平和上川岛最大日降水概率属Frechet分布,开平和台山属Weibull分布,新会属Gumbel分布;各站日降水峰值概率比汛期降水峰值概率大一个量级。不同重现期,上川岛极端日降水事件阈值均显著高于其它台站。

Using year-to-year maximum temperature, raining season precipitation and maximum daily precipitation data from six observation sites in Jiangmen from 1961 to 2015 and with the statistical methods of linear tendency estimation and generalized extreme value ( GEV ), the distribution of the probability of annu-al maximum temperature, raining season precipitation and maximum daily temperature as well as their return level are studied. The result is shown as follows. 1 ) The probability of annual maximum temperature for these sites is of Weibull distribution with Enping ( Shangchuandao Island) having the maximum (minimum) temperature for peak probability density, and Enping having the largest amplitude of variation and Taishan the smallest one. For relatively low return periods (20 years or less), the threshold of extremely high tem-perature events is the highest in Enping; for return periods more than 50 years, it is the highest in Heshan. 2) The probability of raining season precipitation for these sites is of Weibull distribution with Enping ( Hes-han) having the largest ( smallest) rainfall amount and amplitude of variation for peak probability density. For all periods of return, the threshold of extreme precipitation events is much higher in Enping than that of the other sites and it is the lowest in Heshan. 3 ) The probability of maximum daily precipitation is of the Frechet distribution for Heshan, Enping and Shangchuandao Island, the Weibull distribution for Kaiping and Taishan, and the Gumbel distribution for Xinhui. For all of the observation sites, the probability of daily precipitation peaks is one magnitude of order greater than that of the raining season precipitation peaks. For all return periods, the threshold of extreme daily precipitation events at the site of Shangchuandao Island is much higher than that of the other sites.