青藏高原夏季旱涝年降水准双周振荡及低频环流特征分析  

Analysis of Biweekly Oscillation and Low-Frequency Circulation Characteristics of Summer Precipitation in Drought-Flood Years over the Qinghai-Xizang Plateau

作　　者：王熙曌 张宇 宋敏红 曾钰婷 李天雅 WANG Xizhao;ZHANG Yu;SONG Minhong;ZENG Yuting;LI Tianya(School of Atmospheric Sciences,Chengdu University of Information Technology/Plateau Atmosphere and Environment,Key Laboratory of Sichuan Province,Chengdu 610225,Sichuan,China;Meteorological Center of Southwest Air Traffic Administration,Civil Aviation Administration of China,Chengdu 610200,Sichuan,China)

机构地区：[1]成都信息工程大学大气科学学院/高原大气与环境四川省重点实验室,四川成都610225 [2]中国民用航空局西南空中交通管理局气象中心,四川成都610200

出　　处：《高原气象》2023年第2期320-332,共13页Plateau Meteorology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0102);国家重点研发计划项目(2018YFC1505702);国家自然科学基金项目(91537106,91737306)。

摘　　要：为了研究青藏高原夏季降水的低频振荡特征,利用1978-2017年高原地区62个气象站日降水资料和ERA5高分辨率逐日再分析资料,采用集合经验模态分解(EEMD)、Lanczos滤波以及合成分析方法,对青藏高原夏季旱涝年降水的低频振荡特征、气象要素场变化及环流特征进行了深入分析,揭示了高原地区旱涝年降水低频振荡周期特征、环流特征以及低频风场、涡度场等传播特点。结果表明:(1)高原夏季降水存在10~20天的振荡周期;旱涝年的周期频率不同,涝年振荡频率明显高于旱年;涝年显著的振荡为10~20天和30天以上的振荡,而旱年主要以10~20天的振荡为主。(2)涝年在低频降水强位相,高空低频气旋控制高原主体,高空辐散,低空辐合,来自孟加拉湾偏南风的水汽供应充足,低频扰动强,利于降水发生,自西向东存在低频反气旋-低频气旋-低频反气旋的异常环流分布;反之在低频降水弱位相,高空低频反气旋控制高原主体,高空辐合,低空辐散,暖湿的偏南气流较弱,低频扰动偏弱,不利于降水发生。旱年配置有相似的特征,但低频反气旋-低频气旋-低频反气旋的环流形势不明显,整体上振荡强度较涝年偏弱,低频要素场强度也偏弱。(3)低频波动的传播旱涝年有所不同,涝年高原纬向上高低空为低频振荡的汇区,且经向上也是汇区,振荡汇区降水发生更频繁,故涝年降水偏多。在旱年低频振荡经向上高层由高原向外传播,故旱年低频降水发生偏少。In order to study the characteristics of low frequency oscillation of summer precipitation over Qinghai-Xizang Plateau,based on the daily precipitation data of 62 meteorological stations over the Qinghai-Xizang Plateau from 1978 to 2017 and the high-resolution daily reanalysis data of ERA5.This paper adopted the collection of empirical mode decomposition(EEMD),Lanczos filter and synthesis analysis method.Filter out the years of drought and flood,and analyzed the characteristics of low frequency oscillation,variation of meteorological elements and circulation of precipitation in dry and flood years in summer over the Qinghai-Xizang Plateau.Reveals the drought and flood years,the characteristics of low frequency oscillation period of precipitation in plateau area,the circulation characteristics and low frequency and other transmission characteristics of wind field and vorticity field.The results show that:(1)There is an oscillation period of 10~20 days in summer precipitation over the Qinghai-Xizang Plateau.The period frequency of drought and flood years is different,the oscillation frequency of flood years is obviously higher than that of drought years.In flood years,the significant oscillation is 10~20 days and 30-days oscillation,while in drought years,the oscillation is mainly 10~20 days.(2)In flood years,the low-frequency precipitation phase is strong,the high-altitude low-frequency cyclones control the plateau,the high-altitude divergence,the low-altitude convergence.The water vapor supply from the south of the Bay of Bengal,and the low-frequency disturbance is strong,which is conducive to the occurrence of precipitation,there is an abnormal circulation distribution of low-frequency anticyclone-low-frequency cyclone-lowfrequency anticyclone from west to east.On the contrary,in the low frequency precipitation weak phase,the high frequency anticyclone controlled the main body of the plateau,high altitude convergence,low altitude divergence,the warm and wet southerly air is weak,the disturbance is weak,not condu

关 键 词：青藏高原 降水 低频振荡 旱涝年 EEMD分解 

分 类 号：P426.61[天文地球—大气科学及气象学]