黑龙江省夏季异常降水特征及其对总降水的贡献研究

利用黑龙江省80个气象站1971～2016年6～8月逐日降水资料,参照国家标准规定大雨、暴雨事件为异常降水,以数理统计和贡献率方法分析黑龙江省夏季和6、7、8月异常降水及其贡献率变化特征,探讨异常降水对总降水的贡献。结果表明,1971～2016年,研究区夏季异常降水在时间上呈非连续性发生特征,贡献率呈大幅度波动变化,年际间振幅较大,夏季相同月份内大雨贡献率震荡更强,不同月份内,6月大雨贡献率变化最剧烈,8月暴雨贡献率变化最剧烈;异常降水发生在空间上不存在显著经向或纬向变化规律,呈分散性特征,相同月份内暴雨分散性更突出,不同月份内,6月分散性最显著,7月异常降水则相对集中。贡献率空间离散程度较大站点多分布于松嫩平原、三江平原北部,变化不稳定,松嫩平原为异常降水多发区;1971～2016年,大雨、暴雨对总降水量贡献表征为复杂性和相对性。相同年份多以暴雨占主导地位;不同年份中,其他量级降水具有重要贡献。异常降水密集年份中,日降水量20.0～24.9 mm应多予关注。研究客观表征异常降水对总降水的贡献,避免"降水量"分析的绝对性。

Study on abnormal rainfall characteristics and its contribution to total precipitation in summer in Heilongjiang Province

Based on daily precipitation data from 80 meteorological stations in Heilongjiang Province from June to August during 1971 to 2016, according to the national standards, heavy rain and rainstorm were defined as abnormal rainfall. Change characteristics of the abnormal rainfall and its contribution rate during summer, June, July and August of Heilongjiang Province were investigated by using the mathematical statistics methods and contribution rate, and then this paper discussed the contribution of the abnormal precipitation to the total precipitation. The results showed that the temporal occurrence of the abnormal rainfall events was discontinuous and the contribution rate of the abnormal precipitation changed greatly during summer of each station in the research area, and change range of interannual contribution rate was large. Oscillate of contribution rate of heavy rain was more intense than oscillate of rainstorm in the same month of summer, and in the different months, contribution rate of heavy rain changed most dramatically in June and contribution rate of rainstorm changed most dramatically in August. During the research period, the spatial characteristic of abnormal rainfall was discrete and it did not have obvious change of longitude or latitude. Such characteristics of rainstorm were more prominent than characteristics of heavy rain in same month, and the such characteristics of the abnormal rainfall in June were most significant in different months, but the abnormal rainfall was relatively intensive in July. The stations with a high degree of discrete contribution rate were located on the Songnen Plain and the north of the Sanjiang Plain, where its contribution rate was unstable, and the Songnen Plain was the area of occurrence of abnormal rainfall easily. The contribution of heavy rain and rainstorm to the total precipitation was complicated and relative during 1971 to 2016, and rainstorm dominated in the same year, and the contribution rate was either large or small in different years, which meant that other levels of precipitation in the total precipitation tended to have important contribution. In the years with frequent abnormal precipitation, the daily precipitation which was 20.0 to24.9 mm could not be neglected and should be paid more attention to flood control. This paper used the contribution rate of precipitation to represent the contribution of abnormal precipitation to the total precipitation, which was objective and avoided the absoluteness of the "precipitation" analysis in the past.