广西地区1960～2017年降水结构变化特征

Structure Characteristics of Precipitation in Guangxi Region during 1960-2017

基于1960～2017年广西地区24个气象站的逐日降水资料,利用降水发生率和贡献率,分析了不同降水历时和不同降水等级的变化规律,根据Kendall's tau探讨了不同降水历时和不同降水等级的变化趋势。结果表明,各历时降水发生率随着降水历时增加呈逐渐减少趋势,各历时降水贡献率随着降水历时的增加,呈先增加后减少趋势,3d降水历时的贡献率最大,其次为4d降水历时的贡献率。河池、来宾、龙州、平果、柳州、百色、南宁和围洲岛的1～5d的降水贡献率较大,蒙山、桂平、钦州、东兴、防城、那坡和靖西大于10d的降水贡献率较大;各等级降水的发生率呈小雨>中雨>大雨>暴雨的趋势,而贡献率则呈相反的趋势。东兴、防城、北海、钦州和涠洲岛的暴雨贡献率较高,其次为融安、都安、桂林、平果、凤山和灵山;在研究时间段内,降水历时短的降水发生率呈增加趋势的站点较多,降水历时长的降水发生率呈减少趋势的站点较多。各历时降水贡献率的变化趋势和发生率基本一致。各等级降水的贡献率和发生率的变化趋势也基本一致,表现为小雨呈减少趋势,大雨和暴雨呈增加趋势,中雨则表现为发生率增加趋势的站点偏多,而贡献率减少趋势的站点偏多。

Based on the daily precipitation data of 24 rain gauge stations in Guangxi during 1960 to 2017, the incidence rate and contribution rate were used to analyze the change laws of different precipitation duration and precipitation grade, and its variation trends were discussed according to the Kendall’s taus. The results indicate that the incidence rate for different durations decreases with the increase of precipitation durations, while the corresponding contribution rate first increases then declines. The contribution rate of 3d precipitation duration has the maximum value, then is the 4 d precipitation duration. The contribution rates of 1 5 d precipitation duration are higher in Hechi, Laibin, Longzhou, Pingguo, Liuzhou, Baise, Nanning and Weizhoudao. The contribution rate of more than 10d precipitation duration are higher in Mengshan, Guiping, Qinzhou, Dongxing, Fangcheng, Napo and Jingxi. The trends of incidence rate for different precipitation are descending sort as light rain, moderate rain, heavy rain, and rainstorm, while the trends of contribution rate for different precipitation are reverse. The contribution rates of rainstorm are higher in Dongxing, Fangcheng, Beihai, Qinzhou and Weizhoudao stations, followed by Rongan, Duan, Guilin, Pingguo, Fengshan and Lingshan stations. For most of stations, the incidence rate of shorter precipitation durations increases, while the rate of longer precipitation durations decreases. The trends are similar between incidence rate and contribution rate for precipitation durations. The trends of light rain decrease, heavy rain and rainstorm increase for incidence rate and contribution rate. Most of stations are shown upward trends in moderate rain for incidence rates, but decrease for contribution rates.