摘要
亚洲高空西风急流在青藏高原分为南北两支,并呈现强烈的协同变化特征.春季,位于南北支急流间的塔克拉玛干沙漠沙尘活动频繁,而沙尘气溶胶往往通过改变局地热力状况对天气气候产生重要影响,因此,探究沙尘气溶胶影响春季青藏高原南北两支急流协同变化的物理过程具有重要意义.本文利用欧洲中期天气预报中心再分析数据集ERA5和美国国家航空航天局大气再分析数据集MERRA-2,聚焦春季塔克拉玛干沙尘气溶胶的热力效应,分析青藏高原南北两支急流的协同响应过程.结果表明,当塔克拉玛干沙漠沙尘偏强时,往往导致北支急流显著偏北,南支急流强度偏弱,呈现两支急流在位置上的远离和强度上的北强南弱.沙尘气溶胶主要通过“直接”和“间接”热力作用对急流协同变化产生影响.在沙尘偏强年份,其“直接”热力作用表现在:塔克拉玛干沙漠沙尘的辐射效应使对流层的中低层升温,加大(减弱)北侧(南侧)温度经向梯度,使得两支急流在位置上出现远离、强度上出现北强南弱的协同变化;“间接”热力作用则表现为:随着急流位置和强度的改变,使得沙尘关键区及其北部出现异常高压,绝热下沉过程导致其在中高层也呈显著增温,且关键区西部的南风异常输送暖平流,结合非绝热加热,使得沙尘关键区的升温范围在纬向和经向均得以放大,大范围低层到高层一致的升温,进一步促进了两支急流互相远离、北强南弱的协同变化.
The upper-level westerly jet in Asia bifurcates into northern and southern branches over the Qinghai-Tibet Plateau,exhibiting significant synergistic variations.In spring,the Taklimakan Desert,located between the northern and southern branches of the jet stream,experiences a high frequent of dust activities.The presence of dust aerosols significantly impacts weather and climate by inducing alterations in local thermal conditions.Therefore,it is of great significance to explore the physical mechanisms underlying the impact of dust aerosols on the synergistic variations of the northern and southern branches of the jet stream over the Tibetan Plateau during springtime.Utilizing the ERA5 dataset from the European Centre for Medium-Range Weather Forecasts(ECM_(W)F)and the MERRA-2 dataset from NASA Atmospheric reanalysis,this study focuses on investigating the thermal impacts of Taklimakan dust aerosols during spring and revealing the collaborative response mechanism of the northern and southern jet streams over the Tibetan Plateau.The results show that during periods of intense dust activity in the Taklimakan Desert,there is an obvious northward shift in the northern branch jet stream,while the southern branch jet stream weakens considerably,that is,the two jet streams are far away in position,the northern jet become stronger and the southern become weaker.The impact of dust aerosols on the synergistic variation of the jet stream is primarily mediated by both“direct”and“indirect”thermodynamic mechanisms.The"direct"thermal effect is that the radiation effect of dust in the Taklimakan Desert heats up the middle and lower troposphere,enlarges(weakens)the temperature meridional gradient in the north(south)side,and makes the two jet streams appear far away in position,and the intensity appears strong in the north and weak in the south.The"indirect"thermal mechanism is the alterations in the position and intensity of the jet stream lead to anomalous high pressure occurrences within the dust key area and its northern section,subsequently resulting in a thermally adiabatic descent process that induces obvious warming at middle and upper troposphere.Furthermore,anomalous warm advection caused by the southern wind in the western region of the key area,coupled with diabatic heating,significantly amplified the extent of temperature rising across both zonal and meridional within the dust key area,further promoting the synergistic variation of the two jet streams.
作者
郭彤
黄乾
许潇锋
姚素香
GUO Tong;HUANG Qian;XU XiaoFeng;YAO SuXiang(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CLC-FEMD),Nanjing University of Information Science and Technology,Nanjing 210044,China;Key Laboratory of Aerosol-Cloud-Precipitation,China Meteorological Administration,Nanjing 210044,China;State Key Laboratory of Numerical Simulation of Atmospheric Science and Earth Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《地球物理学报》
北大核心
2025年第8期3025-3036,共12页
Chinese Journal of Geophysics
基金
国家自然科学基金重点项目(42030612).
关键词
沙尘气溶胶
气溶胶光学厚度
青藏高原
高空急流
热力效应
Dust aerosol
AOD(Aerosol Optical Depth)
Tibetan Plateau
Upper-level jet stream
Thermodynamic effect
