青藏高原中东部地表感热趋势转折特征及成因分析  

Characteristics and Causes of Surface Sensible Heat Trend Transition in Central and Eastern Qinghai-Xizang Plateau

作　　者：张璐 王慧 石兴东 李栋梁 ZHANG Lu;WANG Hui;SHI Xingdong;LI Dongliang(Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Key Laboratory of Meteorological Disaster,Ministry of Education,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,Gansu,China)

机构地区：[1]南京信息工程大学大气科学学院/气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室,江苏南京210044 [2]兰州大学大气科学学院,甘肃兰州730000

出　　处：《高原气象》2020年第5期912-924,共13页Plateau Meteorology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0103);国家自然科学基金项目(41305080);江苏高校优势学科建设工程项目(PAPD)。

摘　　要：利用气候变化趋势转折判别模型(PLFIM)分析了1982-2018年青藏高原(下称高原)70个站地表感热通量趋势转折特征,并从高原地温和气温对同期北半球变暖的响应速度,以及大气环流背景场等方面分析其趋势转折的可能原因。结果表明:(1)高原4个气候区的年平均地表感热均在2000年前后发生了由显著减弱到显著增强的趋势转折,其中Ⅱ区(高原东部)最早发生转折(1999年),其次是Ⅰ区(高原北部)和Ⅳ区(高原东南部)(2000年),Ⅲ区(高原西南部)最晚(2002年)。Ⅱ区和Ⅲ区是高原感热趋势转折的关键区。Ⅱ区感热的变化主要由地温的增温加快使地气温差加大所导致,Ⅲ区则主要受地面风速变化的影响,2000年后地面风速的增加对该区感热的趋势转折有重要贡献。(2)2000年之前,北半球中纬度西风急流偏弱且急流轴位置偏南,同时高原北(南)部到高(低)纬度地区温度异常偏高(低),经向温度梯度和气压梯度减小,使得这一时期高原风速持续减小;2000年之后与之前相反,高原风速的减小趋势在这一时期得到缓解,并逐渐转变为增加趋势,进而造成了高原地表感热变化趋势的转折。In this paper,the Piecewise Linear Fitting Model(PLFIM)of climate change was used to analyze the characteristics of the trend transition of the surface sensible heat flux at 70 stations on the Qinghai-Xizang Plateau(hereinafter referred to as plateau)from 1982 to 2018 and the possible causes of the trend change were analyzed from the following aspects:the response rate of the plateau temperature to the warming of the northern hemisphere and the background of atmospheric circulation.Results show that:(1)there is a trend transition from weakening to strengthening in the annual mean surface sensible heat flux on all four climatic zones of the plateau around 2000;the earliest turning point is in 1999 occurred on theⅡzone(the eastern part of plateau),followed by theⅠ(the northern part of plateau)andⅣzones(the southeastern part of plateau)are in 2000,the latest turning point is in 2002 occurred on theⅢzone(the southwest part of plateau);theⅡandⅢzones are the key areas with the trend transition of surface sensible heat flux,and the change of the surface sensible heat flux on theⅡzone is mainly caused by the increased of surface-air temperature difference which due to the rapid increase of the ground temperature,while on theⅢzone,the change of the surface sensible heat is mainly affected by the ground wind speed,and the increase of surface wind speed after 2000 plays an important role in the trend transition of the surface sensible heat flux;(2)in pre-2000 epoch(1982-2000),the mid-latitude westerly jet is weaker and the jet axis is southward in the northern hemisphere;meanwhile,the temperatures in the north(south)part of the plateau to the high(low)latitude are abnormally higher(lower),and the meridional temperature gradient and pressure gradient are decreased,these cause the plateau wind speed to decrease continuously during this period,however,the background of the atmospheric circulation is reversed in post-2000 epoch(2000-2018),which alleviates the decreasing trend of the plateau wind speed and causes

关 键 词：青藏高原 感热通量 地面风速 趋势转折 地气温差 

分 类 号：P466[天文地球—大气科学及气象学]