甘肃东西区夏季不同强度降水事件天气成因分析  

Analysis of the Weather Causes of Summer Precipitation Events with Different Intensities in the Eastern and Western Regions of Gansu Province

作　　者：杨庆怡 朱姜韬 田韬 YANG Qing-yi;ZHU Jiang-tao;TIAN Tao(Lanzhou Resources and Environment Vocational and Technical University,Lanzhou,Gansu 730021;School of Atmospheric Science,Lanzhou University,Lanzhou,Gansu 730000;Chinese People’s Liberation Army 93811 Unit,Lanzhou,Gansu 730000)

机构地区：[1]兰州资源环境职业技术大学,甘肃兰州730021 [2]兰州大学大气科学学院,甘肃兰州730000 [3]中国人民解放军93811部队,甘肃兰州730000

出　　处：《安徽农业科学》2024年第2期197-203,共7页Journal of Anhui Agricultural Sciences

基　　金：兰州资源环境职业技术大学科技创新团队项目“甘肃河西NDVI演变特征及其对不同强度降水变化的响应”(X2022A-04)。

摘　　要：基于1961—2018年甘肃省逐日降水格点资料和NECP/NCAR再分析资料,依据逐年降水变化“东西反向”型分布模态,将甘肃以104°E为界分为东西两区开展不同强度的降水事件变化研究及成因分析。结果表明:中降水事件在两区夏季降水的占比均超46%,占主导作用;西区强、中降水事件发生频次呈上升趋势,东区各强度降水事件频次均呈下降趋势。天气成因分析表明,甘肃东西区降水偏强时,南亚高压异常增强,提供了较好的高空辐散条件,西太平洋副热带高压偏强、偏北或偏西,中纬度地区“+-+”的位势高度异常促使冷暖空气增强并交汇于甘肃地区,西风带波动小槽的发展,配合近地层高原东侧低涡将低纬度水汽接力向西北输送,导致降水发生;相较于东区,西区降水夏季风系统异常更强,西风带波动显著,位势高度负异常位置偏北。Based on the daily precipitation grid data and NECP/NCAR reanalysis data from 1961 to 2018 in Gansu Province,and based on the“east⁃west reverse”distribution mode of annual precipitation changes,Gansu was divided into two regions with 104°E as the boundary to conduct research on precipitation event changes of different intensities and analyze their causes.The results showed that the proportion of moder⁃ate precipitation events in summer precipitation in both regions exceeded 46%,accounting for the dominant role;the frequency of strong and moderate precipitation events in the western region showed an upward trend,while the frequency of various intensity precipitation events in the eastern region showed a downward trend.The analysis of weather causes showed that when the precipitation in the eastern and western regions of Gansu was relatively strong,the South Asian high pressure abnormally strengthened,providing good conditions for high⁃altitude divergence.The subtropical high pressure in the western Pacific was relatively strong,northward or westward,and the abnormal height of the“+-+”po⁃tential in the mid latitude region promoted the enhancement of cold and warm air and its convergence in the Gansu region.The development of the fluctuation trough in the westerly belt,combined with the low vortex on the eastern side of the near surface plateau,will relay low latitude water vapor to the northwest,leading to precipitation.Compared to the eastern region,the summer monsoon system of precipitation in the west⁃ern region was more anomalous,with significant fluctuations in the westerly belt and a negative anomaly position in the geopotential height to⁃wards the north.

关 键 词：不同强度降水 夏季风 南亚高压 西风急流 甘肃东西区 

分 类 号：S162[农业科学—农业气象学]