青藏高原南侧大气热源对江淮流域南北偶极型降水季节内振荡的调节  

Modulation of the atmospheric heat source over the southern Tibetan Plateau on the intra-seasonal oscillation of the north-south dipolar precipitation in the Yangtze-Huaihe Valley

作　　者：孙嘉路 陈兵 王昊 钟珊珊[1] SUN Jialu;CHEN Bing;WANG Hao;ZHONG Shanshan(Key Laboratory of Meteorological Disaster,Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,China;Jiangsu Climate Center,Nanjing 210019,China;Heilongjiang Climate Center,Haerbin 150030,China;Changshu Meteorological Bureau,Jiangsu Changshu 215500,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心/气候与环境变化国际合作联合实验室,南京210044 [2]江苏省气候中心,南京210019 [3]黑龙江省气候中心,哈尔滨150030 [4]常熟市气象局,江苏常熟215500

出　　处：《气象科学》2024年第6期1061-1071,共11页Journal of the Meteorological Sciences

基　　金：国家自然科学基金重大研究计划之重点支持资助项目(92158203);国家自然科学基金资助项目(42375045,41775047);江苏省气象局科研基金重点资助项目(KZ202102)。

摘　　要：基于1979—2018年我国台站观测的逐日降水和JRA-55大气逐日再分析资料,本文分析了夏季江淮流域南北偶极型降水10~30 d季节内振荡(Intra-seasonal Oscillation, ISO)特征,并重点探讨了青藏高原南侧大气热源不同强度的加热状态对江淮流域南北偶极型降水ISO的峰值和谷值的调节作用。结果表明,当高原南侧为强加热状态,有利于增强江淮流域夏季降水的南涝北旱;而当高原南侧为弱加热状态,则易于加剧江淮流域的南旱北涝。这主要由于青藏高原南侧异常强加热,对流层低层异常热低压增强,加热气泵的抽吸效应有利于孟加拉湾水汽向高原辐合。同时,高原南侧的辐合上升运动又促使其对流层上层气流辐散增强,导致自西向东传播的欧亚遥相关波列的异常反气旋性环流在抵达高原西部时,将向高原南侧扩张并增强,进一步加剧上层气流的辐散,加强对流层低层的水汽输送,江淮流域南部充足的水汽供应导致降水增强。此外,高原南侧和孟加拉湾形成的北正南负的非绝热加热的经向不均匀性分布,促使异常局地负涡源的产生,增强了孟加拉湾的反气旋性环流外围水汽向高原的辐合并转向江淮南部。当高原南侧为弱加热状态时,情况则相反。On the basis of the station-based daily precipitation in China from 1979 to 2018 and the atmospheric fields from Japanese 55-year Reanalysis(JRA-55),this paper analyzed the characteristics of the 10-30-day Intra-seasonal Oscillation(ISO)of the north-south dipolar precipitation in the Yangtze-Huaihe Valley(YHV)in summer.In particular,the modulation of the atmospheric heat source over the southern Tibetan Plateau(TP)with different intensity was investigated on the peak and trough of ISO of the north-south dipolar precipitation in the YHV.It is found that strong(weak)heating over the southern TP induces enhanced floods(drought)in the southern YHV and drought(floods)in the northern YHV.The anomalous strong heating over the southern TP intensifies the anomalous warm low in the lower troposphere,with the pumping effect favorable to the water vapor from Bay of Bengal converging towards TP.Meanwhile,the converging and upward motion over the southern TP induces upper-level divergence.Thus,the anomalous anticyclonic circulation in the westward propagating Eurasian wavetrain is enhanced and expanded southward when reaching the northwestern TP,further strengthening the upper-level divergence,the water vapor transport in the low troposphere is strengthened,and the sufficient water vapor supply in the southern YHV leads to the enhanced precipitation.Moreover,the inhomogeneous meridional distribution of the adiabatic heating,i.e.,positive over the southern TP and negative over the Bay of Bengal,results in genesis of the anomalous negative vorticity source and enhancement of water vapor from the periphery of anticyclonic circulation over the Bay of Bengal converging to TP and then veering towards the YHV.It is on the contrary when the anomalous heating over the southern TP is weak.

关 键 词：江淮流域 南北偶极型降水 季节内振荡 青藏高原 大气热源 

分 类 号：P461.2[天文地球—大气科学及气象学]