影响初夏江淮流域年代际极端干旱的欧洲关键区能量演变特征分析  

Analysis of Energy Evolution Characteristics of Key Areas in Europe Affecting Decadal Extreme Drought in Yangtze-Huaihe River Basin during the Pre-summer Period

作　　者：刘诗梦 张杰[1] 于涵 LIU Shimeng;ZHANG Jie;YU Han(Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological isaster of Ministry of Education,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Climate center of Inner Mongolia autonomous region,Hohhot 010000,Inner Mongolia,China;Liaoyang Meterological Bureau,liaoyang 111000,Liaoning,China)

机构地区：[1]气象灾害预报预警与评估协同创新中心/气象灾害省部共建教育部重点实验室,南京信息工程大学,江苏南京210044 [2]内蒙古自治区气候中心,内蒙古呼和浩特010000 [3]辽阳市气象局,辽宁辽阳111000

出　　处：《高原气象》2020年第1期143-152,共10页Plateau Meteorology

基　　金：国家自然科学基金项目(41975083,41630426)

摘　　要：利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的全球再分析数据,使用局地多尺度能量涡度分析法(localized Multiscale Energy and Vorticity Analysis,MS-EVA)分析了初夏影响江淮流域极端干旱发生的欧洲关键区动能变率的时间特征及其动能收支。结果表明:初夏欧洲关键区高层动能有增长趋势时,我国江淮流域极易发生极端干旱事件。该处增长的动能主要来自天气尺度动能的传输,其次来自气压梯度力做功和动能的垂直输送;动能向有效位能的转换和季节平均尺度动能的传输是高层动能流失的原因。深入研究三项动能来源因子后发现:上层增加的动能一部分来自低层北大西洋东岸和欧洲大陆西南地区的动能东传,在欧洲辐合后向上输送,为高层传递能量;同时,由于关键区地面热强迫增强,使垂直风切变增大,大气斜压稳定度降低,气压梯度力做功项增大,使得高层动能得到补充。在此期间,由于地面加热,天气尺度传输项对高层动能的传输量也增多。关键区增加的净能量经西风环流在江淮地区辐合,有助于该地上空的脊增强,促进了极端干旱事件发生。该结果从能量转换角度探究了江淮流域干旱发生的部分成因,为干旱预估提供依据。Based on the global reanalysis data provided by the European Center for Medium-Range Weather Forecasts(ECMWF),this paper analyzes the time characteristics of the dynamic variability and kinetic energy budget of the European key area that lead to extreme drought in the Yangtze-Huaihe river basin during the pre-summer period by using the multiscale energy and vorticity analysis(MS-EVA).It is found that in the early summer when the kinetic energy of high-level in European key area had a tendency to increase,extreme drought events easily occurred in the Yangtze-Huaihe river basin.The kinetic energy here mainly comes from the energy conversion from synoptic-scale eddy,followed by the pressure work and vertical transport of kinetic energy;Buoyancy conversion and energy conversion from the mean flow are outputs of high-level kinetic energy.Some of the increasing upper-strata kinetic energy comes from eastward kinetic energy of the east coast of the North Atlantic and the southwestern continent of Europe,and these energy is transported upwards after convergence in Europe to transfer energy to the upper strata which can transfer energy to higher levels.At the same time,due to the increase of ground heating in the key area,the vertical wind shear increases,the baroclinic stability decreases and the pressure work increases,which makes the upper kinetic energy supplemented.During this period,the energy conversion from synoptic-scale eddy also increased due to ground heating.The net energy added in the key area converges in the Yangtze-Huaihe river basin by the westerly circulation,which helps to enhance the ridge above the ground and promotes the occurrence of extreme drought events.This result explores part of the causes of drought in the Yangtze-Huaihe river basin from the perspective of energy conversion and provides a basis for drought prediction.

关 键 词：动能 气压梯度力做功项 动能平流项 天气尺度传输项 

分 类 号：P467[天文地球—大气科学及气象学]