宁夏汛期降水直接影响因子贡献的定量分析

Quantitative estimation of influence factors contribution to precipitation during rainy season in Ningxia

利用宁夏24个气象观测站1991—2012年汛期逐6 h降水量资料及相应时段ECMWF的垂直速度、温度、比湿资料,通过相关、岭回归和因子的定量贡献等方法研究了宁夏降水直接影响因子对降水量的贡献及不同地区降水的关键影响因子.结果表明,宁夏汛期降水和当地上空中高层的温度显著相关,但南北差异较明显;降水和比湿在中低层显著相关;南部降水和比湿在高层显著相关,南部汛期降水大多和整层上升运动显著相关;中北部降水只和高层上升运动显著相关,韦州站是降水影响因子相关差异的南北分界点.宁夏北部和南部地区低层比湿对降水贡献较大,地形对降水量也有一定的影响;对宁夏不同气候区域而言,引黄灌区和南部山区比湿对汛期降水的贡献最大,中部干旱带降水因子的贡献则尚存在一定不确定性.

Based on 6 hours interval precipitation data from 24 meteorological stations and vertical velocity, temperature, specific humidity data of ECMWF during Ningxia rainy season, 1991--2012, the key impact factors of precipitation and their contribution to the precipitation were analyzed by means of correlation analysis, ridge regression and quantitative estimation in different areas of Ningxia. Results showed that the correlation was significantly and very different in the north and the south between precipitation and the middle-upper level temperature. For specific humidity, the correlation was significantly at the lower-middle level and the upper level of south. For vertical velocity, the correlation was mostly significantly between the southern precipitation and the ascending motion throughout the whole layer, was significantly between the central and northern precipitation and the middle-upper level ascending motion. Weizhou station was north-south dividing point of the correlation. Specific humidity in north and lower level south made a larger contribution to precipitation; meanwhile, terrain also has some influence. For climate region, the biggest contribution had come from specific humidity in Yellow River irrigation region and southern mountain region, the contribution of influence factors to perception in the drought of middle area were still some uncertainties.