| The Arctic and the Qinghai-Tibet Plateau are sensitive areas of global climate change and are the key areas for studying global climate change.Moreover,the Arctic and the Qinghai-Tibet Plateau are both in the northern hemisphere where human activities are frequent.They have been polluted easily and have received more attention from scholars.This paper uses the NCEP/NCAR FNL objective analysis data to drive the WRF(Weather Research and Forecasting Model)to simulate the impact of different meteorological conditions on the transmission of ideal tracer emissions from low latitude area to the high latitude region in 2010.The total transmission,transmission characteristics and transmission mechanism are analyzed,which provides a reference for understanding the dynamic mechanism of pollutants transmitted to the high latitude region from the low latitudes.In addition,the paper also simulates the transmission process of ideal tracer emissions to the plateau from five different regions(the Qinghai-Tibet Plateau,South China,South Asia,Southeast Asia,and eastern China)during the monsoon period,and studies its transmission characteristics and mechanism,and quantifies the different proportions of local and external sources of pollution in the plateau,and provides reference for understanding the sources of pollution in the plateau.The main results of the thesis are as follows:(1)The highest emissions from the low latitude region to the high latitude region in December,peaked at ~44? of total emissions,followed by September and June,reaching ~7.5? and ~7? respectively,with the least in March,about~0.105?.The time required for emissions to be transported to the high latitude region in December is the shortest,about three days,followed by September and June,which are 6 days and 5 days respectively.The longest time for emissions to be transmitted to the high latitude region in March is about 9 days;the height of emissions in the high latitude region is different under different meteorological conditions.The height is lower in March,mainly concentrated between 850-700 hPa,between 400-200 hPa in September,and higher concentrations of emissions between 850-200 hPa in June and December;The path of emissions is mainly controlled by the circulation field and the wind field.The strong radial southerly wind and cyclone system facilitates the transmission of emissions to the high latitude region.A continuous and stable low-pressure system is the most important reason for emissions to be transmitted to the high latitude region in December.The strength of the East Asian trough has little effect on the transmission.The important one is the shape.The direction of the trough line has a great influence on the transmission.The more horizontal the wind direction is behind the trough,the more vertical the wind direction is.The northwest-southeast trend of this trough line is more favorable for transmission.The shape of the trough affects the radial southerly wind,which is the root cause of the impact of transmission.(2)In different periods,the sources of pollution in the plateau areas at different altitudes are different and have a great relationship with the transmission environment.In May,pollution in South Asia easily invaded the plateau.In June,pollution in eastern China was easier,and in July,pollution from South Asia was the most invaded to the plateau;the impact of initial emissions on transmission was greater than the impact of the area of the discharge area,and the transmission height was mainly concentrated below 500 hPa.In July,the upper troposphere is also an important transmission channel.During the transmission of tracer emissions in the lower troposphere,the southwest monsoon and the southeast monsoon and the westerly wind belt are the main factors affecting the transmission;In the transmission process of the upper troposphere,the anti-cyclonic system formed by the South Asian high pressure plays an important role in transmission. |
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