近30年六盘山东与西坡降水及空中水汽条件差异特征分析

利用1989—2018年欧洲中期天气预报中心(ECMWF)的ERA-Interim高时空分辨率(0.125°×0.125°)再分析资料以及气象站降水观测资料,对六盘山区近30年东坡与西坡降水及空中水汽条件差异特征进行诊断分析。结果表明:①近30年六盘山区大气可降水量、700hPa比湿、水汽通量与降水量空间分布特征较为一致,呈东高西低、南大北小的特征。②六盘山区的水汽主要来源于低层孟加拉湾、南海及印度洋暖湿气流的水汽输送。③六盘山区的水汽输送特征表现为700hPa和750hPa以西南风水汽输送为主导,750hPa以下六盘山东侧为东南风迎风坡,受地形强迫的影响,东南暖湿气流在东坡抬升。④六盘山系东坡存在高层辐散、低层辐合或弱辐散的动力场配置,加之地形、东亚季风与天气系统之间相互作用的共同影响,造成六盘山区降水及空中水汽条件呈东高西低的分布特征。初步的研究结果可揭示区域空中水汽条件的分布特征,为该地云水资源开发提供可参考性依据。

Analysis of Difference Characteristics of Precipitation and Air Water Vapor Conditions over East and West Slopes of Liupan Mountain in Recent 30 Years

Based on the high spatial and temporal resolution(0.125°×0.125°)reanalysis data of ERAInterim issued by the European Centre for Medium-Range Weather Forecasts(ECMWF)and the precipitation observation data of the meteorological stations from 1989to 2018,the characteristics of precipitation and air water vapor conditions on the east and west slopes of Liupan Mountain in recent 30 years are analyzed.The results show that:(1)The spatial distribution characteristics of the atmospheric precipitation,700hPa specific humidity and water vapor flux in the Liupan mountain area are relatively consistent with these of the precipitation in recent 30years,with the characteristics of high in the east and low in the west,large in the south and small in the north.(2)During the summer main precipitation processes,the water vapor in the Liupan mountain area mainly comes from the lower layer of the Bay of Bengal,South China Sea and Indian Ocean.(3)The water vapor transport characteristics over the Liupan Mountain area are as follows:the water vapor transport is dominated by the southwest wind in 700hPa and 750hPa;the east side of the Liupan Mountain is the windward slope of the southeast wind below 750 hPa;influenced by the landform forcing,the southeast warm and wet air flow rises on the east slope.(4)The divergence field of water vapor flux has a structure of divergence at upper levels and convergence or weak divergence at lower levels over the eastern slope of the Liupan Mountain.Combined with the interaction of topography,East Asian monsoon,and various weather systems,the distribution characteristics of precipitation and air water vapor conditions in the Liupan mountain area are high in the east and low in the west.The preliminary results can reveal the characteristics of regional air water vapor conditions and provide a reference basis for the development of cloud water resources.