陕西省2021年极端秋雨成因分析  

Causes of Extreme Autumn Rain in Shaanxi Province in 2021

作　　者：李静睿 赵强 刘佩佩[1,2] 陈小婷 LI Jingrui;ZHAO Qiang;LIU Peipei;CHEN Xiaoting(Ankang Meteorological Bureau,Ankang 725000,China;Key Laboratory of Eco-Environmental Meteorology of Qinling and Loess Plateau,Xi'an 710015,China;Shaanxi Meteorological Observatory,Xi'an 710015,China)

机构地区：[1]安康市气象局,陕西安康715000 [2]秦岭和黄土高原生态环境气象重点实验室,陕西西安710015 [3]陕西省气象台,陕西西安710015

出　　处：《沙漠与绿洲气象》2024年第3期32-39,共8页Desert and Oasis Meteorology

基　　金：陕西省自然科学基础研究计划资助项目(2021JQ-957);陕西省重点研发计划(2021NY-183);秦岭和黄土高原生态环境气象重点实验室面上基金项目(2022G-3)。

摘　　要：利用NCEP/NCAR 2.5°×2.5°的逐月再分析资料和NOAA提供的逐月海温资料等从海温异常、大尺度环流异常、水汽输送异常等角度分析2021年秋季陕西降水异常偏多的原因,结果表明:(1)小波交叉谱分析显示Ni?o3.4区海温距平与陕西秋季降水存在2~4 a的共振周期,前期冬季海温与次年秋季降水关系呈正相关的共振周期。(2)受双峰型La Nina事件影响,2021年9-11月西太平洋副热带高压(简称“副高”)控制的范围明显偏大,副高脊线位置较气候态偏北1°,西伸脊点较气候态偏西23°,造成主雨带偏西偏北。(3)中低层西北太平洋到我国华北北部的异常反气旋,与孟加拉湾北侧异常的气旋中心,造成气流在我国西北地区东部异常辐合。(4)从水汽收支来看,陕西2021年秋季水汽净流入较气候态偏多66.7%,尤其是东边界的异常水汽输送,还增强了低层冷垫,利于暖湿气流在冷垫上爬升导致陕西降水较常年异常偏多。Based on the monthly reanalysis data provided by NCEP at a resolution of 2.5°×2.5°and monthly SST data provided by NOAA,this study analyzed the causes of extreme autumn rain in Shaanxi province during autumn 2021 through the perspectives of SST,large-scale circulation,and water vapor transport.The analysis reveals a 2-4 year resonance period between the SST anomaly in the Nino3.4 region and autumn precipitation in Shaanxi province,with a positive correlation existing between the SST in early winter and the precipitation in the following autumn.In September to November 2021,the La Nina event with two peaks significantly expanded the range controlled by the subtropical high.The position of the subtropical high ridge was 1 degree north of the climatic state,and the westward ridge point was 23 degrees west of the climatic state,resulting in the main rain belt shifting to the west and north.The abnormal anticyclone from the middle and low northwest Pacific Ocean to the northern part of North China and the abnormal cyclone center on the northern side of the Bay of Bengal caused the abnormal convergence of the air flow in the eastern part of the northwest of China.In autumn 2021,the net water vapor inflow in Shaanxi was 66.7% higher than that in the climatic state,especially the abnormal water vapor transport at the eastern boundary in the middle and lower layers,which further enhanced the uplift of the cold cushion in the lower layers,resulting in more precipitation than usual in Shaanxi.

关 键 词：海温异常 小波交叉谱分析 环流异常 水汽输送异常 

分 类 号：P426.6[天文地球—大气科学及气象学]