摘要
利用1961-2020年降水资料、NCEP/NCAR 2.5°×2.5°和ERA5资料,对鄂东北春季极端强降水个例天气系统及物理量的异常度、配置与降水落区的关系进行分类对比研究.结果发现:(1)鄂东北春季极端强降水有3种典型形势,即地面倒槽型、冷锋前沿型、暖低压型.3类极端强降水过程500 hPa均有南支槽缓慢东移,湖北以东、东北地区到日本有异常强的高压或高压脊,东高西低的形势使降水持续时间长.850 hPa偏南急流异常强盛,鄂东北位于切变辐合区.强降水发生前地面暖低压异常发展,为强降水提供了有利的环境条件.(2)鄂东北大多数春季极端强降水与低层水汽、中低层垂直速度的异常密切相关.鄂东北及周边为低层水汽辐合和垂直速度异常度负值之和大值区.
Abstract
Based on the analysis of precipitation data from 1961 to 2020,in conjunction with NCEP/NCAR and ERA5 datasets,the study examines the correlation between the area of precipitation,the abnormality of the weather system,and physical quantities related to spring's extremely heavy precipitation events in northeast Hubei.The research categorizes and compares the relationship,yielding the following findings:(1)Three primary scenarios typify instances of extremely heavy precipitation:ground inverted trough,cold front,and warm low-pressure systems.Across all three types,the 500 hPa south branch trough moves sluggishly eastward.Abnormally robust high-pressure systems or high-pressure ridges are observed from the eastern regions of Hubei and northeast China to Japan.The interplay of the eastern high-pressure system and western low-pressure conditions contributes to prolonged precipitation.Additionally,the 850 hPa southerly jet exhibits exceptional strength,positioning northeast Hubei in the zone of shear convergence.Before the onset of heavy precipitation,abnormal ground heating and the development of low pressure create a conducive environment for the occurrence of extremely heavy precipitation.(2)The majority of spring's extremely heavy precipitation in northeast Hubei demonstrates a close association with anomalies in low-level water vapor and low-level vertical velocity.Particularly,the northeastern and surrounding areas of Hubei manifest an extensive area characterized by the summation of the negative values of low-level water vapor convergence and vertical velocity anomalies.
维普
万方数据