乌鲁木齐汛期降水集中度和集中期时空变化特征

Change in Precipitation Concentration Degree and Precipitation Concentration Period of Flood Season in Urumqi

利用乌鲁木齐5个国家级气象站1978—2019年5—9月逐日降水资料,统计分析逐候降水集中度(PCD)和集中期(PCP)变化趋势和时空分布特征。结果表明:近42 a乌鲁木齐汛期降水集中度和集中期均呈微弱下降趋势,表明汛期降水分配趋于均匀,降水集中期呈逐渐提前趋势。汛期降水集中度和集中期空间分布差异显著,降水集中程度由西向东逐渐增大,降水集中期出现时间由北向南逐渐推迟。汛期降水集中度在整个研究期内存在6、15 a左右周期变化,降水集中期存在12 a左右周期变化。对多降水年和少降水年降水集中度和集中期合成分析,发现少降水年降水集中程度高于多降水年,而降水集中期明显晚于多降水年。

Based on the daily precipitation data at 5 meteorological stations in Urumqi from May to September during 1978-2019,the variation trend and spatial-temporal distribution characteristics of precipitation concentration degree(PCD)and precipitation concentration period(PCP)were analyzed.The results show that:,the PCD and PCP of flood season in Urumqi show a weak downward trend during the recent 42 years,which indicates that the precipitation distribution in flood season tends to be uniform,and the PCP gradually advances.There are significant differences in the spatial distribution of PCD and PCP of flood season.The PCD increases gradually from west to east,and the occurrence time of PCP delays gradually from north to south.During the whole study period,the precipitation concentration in flood season varies about 6 years and 15 years,while the PCP varies about 12 years.It is found that the PCD in less precipitation years is higher than that in more precipitation years,and the PCP is obviously later than that in more precipitation years.