摘要
基于1980-2017年京津冀地区定时观测资料、欧亚陆面积雪资料、欧洲中期天气预报中心(European Centre for Medium-range Weather Forecasts,ECMWF)再分析资料,美国国家环境预报中心/大气研究中心(NCEP/NCAR)再分析资料以及英国哈德莱中心提供的海冰密集度资料,分析了秋季10-11月京津冀霾日频数年际变率与同期欧亚积雪的物理联系,并通过气候统计诊断和敏感性试验探讨了积雪异常影响京津冀10-11月霾日频数年际变率的可能机理。结果表明,10-11月京津冀霾日频数年际变率与同期东欧-西伯利亚平原地区(记为R Eu;50°~60°N,40°~80°E)积雪厚度和积雪覆盖度均呈现显著的正相关关系。R Eu积雪正异常与其西北侧的挪威海-巴伦支海海域以及北欧到东欧地区上空大气冷源密切联系,该冷源可激发一个自上述区域途经R Eu一直到东北亚的准正压大尺度纬向Rossby波列来调制影响京津冀霾日频数年际变率的关键环流系统,即东北亚异常反气旋。上述异常环流背景下,京津冀地区对流层低层为偏南风异常所控制,稳定大气层结易于建立,边界层高度偏低、地面风速偏弱且相对湿度偏高。该环境条件有利于霾天气发生发展,使得同期霾日偏多。作为预测信号,当前期9月楚科奇海-西波弗特海海冰偏少(多)时,10-11月京津冀霾日可能偏多(少)。
Based on the ground-timing observation data in the Beijing-Tianjin-Hebei(BTH)region,the surface Eurasian snowpack data,the ECMWF and the NCEP/NCAR reanalysis datasets,and the Hadley Centre's Arctic sea ice concentration data from 1980 to 2017,the present study investigates the physical linkage between the interannual variations of haze frequency over the BTH region in October-November and the concurrent Eurasian snowpack.Furthermore,the connected potential mechanisms are also discussed via the climatic statistical diagnosis and numerical sensitive experiments.Results show that the interannual variability of the October-November haze frequency over the BTH region shows a significant positive correlation with the simultaneous snow depth as well as the snow-cover extent over the eastern Europe-Siberian plain(R Eu for short;50°-60°N,40°-80°E).Those localized positive snowpack anomalies are closely tied to the anomalous atmospheric diabatic cooling areas to its northwest side,i.e.Norwegian Sea-Barents Sea sector and the northern and eastern European regions,which can in turn excite a large-scale zonal quasi-barotropic Rossby wave train from the area around the key area R Eu to the Northeast Asia,modulating the climate variability in the concurrent Northeast Asian anticyclonic anomaly,a key circulation system leading to a higher number of the simultaneous haze days in the BTH region.Under such circumstances,the lower troposphere over the BTH region is dominated by anomalous southerly winds.The in situ stable stratification can be easily set up,and the boundary layer height is lower than normal,along with the weakened surface wind velocity and enhanced surface relative humidity.The above environmental conditions are conducive to the occurrence and development of localized haze weather,thus resulting in more frequent haze events.As a precursory signals,the preceding decrease in the September Chukchi-West Beaufort Sea ice may lead to a higher number of October-November haze days over the BTH region,and vice versa.
作者
汪靖
常越
杨修群
柳艳菊
何金海
WANG Jing;CHANG Yue;YANG Xiuqun;LIU Yanju;HE Jinhai(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;Tianjin Insitute of Meteorological Science,Tianjin 300074,China;Guangdong Meteorological Bureau,Guangzhou 510640,China;School of Atmospheric Sciences,Nanjing University,Nanjing 210023,China;National Climate Centre,Beijing 100081,China)
出处
《气象科学》
北大核心
2020年第5期711-720,共10页
Journal of the Meteorological Sciences
基金
大气重污染成因与治理攻关项目(DQGG0104)。
关键词
京津冀地区
10—11月霾日频数
年际变率
积雪
环流异常
BTH region
October—Novemberhaze frequency
interannual variations
snow cover
circulation anomalies
作者简介
通信作者:何金海,hejhnew@nuist.edu.cn。
