| The water vapor,carbon monoxide,and ozone data detected by the MLS microwave edge detector carried by the American AURA satellite and the reanalysis data of NCEP / NCAR were used to analyze the distribution characteristics of water vapor,carbon monoxide,and ozone in the upper troposphere to lower stratosphere of the plateau in 2018.The related relationship between the authors was analyzed.At the same time,the HYSPLIT mode based on the Lagrangian method was used to track the backward trajectory of air blocks over Lhasa,and the following conclusions were obtained:(1)Through the analysis of the characteristics of the water vapor distribution within the year,it can be concluded that the distribution of water vapor in spring,autumn and winter basically shows a state of high in the south and low in the north,decreasing from south to north.In summer,the water vapor in the UT / LS area of the plateau and surrounding areas is affected by the combination of the South Asian high pressure and deep convection.The vertical motion is greatly enhanced,and the ascending airflow can reach a height of 100 h Pa or higher,so that the water vapor can be transmitted upward from the upper troposphere.At the same time,there are mountain blocks on the south side of the plateau,warm and humid air is lifted up a lot,and water vapor is condensed.In addition to the role of the South Asian summer monsoon,the water vapor in the south of the plateau is much more than that in the north.(2)Through the analysis of the water vapor distribution on the plateau and its east and west sides,it is known that under the influence of plateau dynamics and thermal effects,the water vapor content in the upper troposphere to the lower stratosphere over the plateau is significantly more than that on the east and west sides,and the west side of the plateau Water vapor increases rapidly with height,but the change trend of water vapor over the plateau at 100 h Pa height and on the east and west sides is consistent.(3)Analysis of the fluctuations of water vapor in different layers of the plateau during the season shows that the overall fluctuations of water vapor at all levels in spring are relatively small,basically within one standard deviation.The overall volatility in summer began to increase,basically within two standard deviations,and the normalized anomaly values of 215 h Pa and 147 h Pa were correlated.The correlation coefficient can reach 0.74,and passed the 99% significance test,indicating that the upper troposphere in summer The water vapor can be transported up to the top of the troposphere,which proves that the water vapor from the troposphere can bring the water vapor to a higher height when the upward airflow is strong.The abnormal increase in water vapor near the top of the troposphere and the lower stratosphere in autumn is not caused by deep convection upward transmission,and there is no abnormal fluctuation of water vapor in the upper troposphere.The overall fluctuation of water vapor in winter is stable,the water vapor content is low,and there is little convection activity.(4)The correlation test between water vapor and carbon monoxide at three heights shows that the water vapor and carbon monoxide have a significant positive correlation from the upper troposphere to the top of the troposphere,and a significant negative correlation in the lower stratosphere.A similar conclusion can be drawn from the correlation test between water vapor and ozone.Water vapor and ozone are negatively correlated in the troposphere,but present a positive correlation in the stratosphere,and both have passed the 95% significance test.When water vapor passes through the top of the troposphere,it may cause freeze-drying and dehydration,which will cause water vapor and carbon monoxide to exhibit a negative correlation in the lower stratosphere.The water vapor entering the stratosphere provides hydroxyl radicals for the photochemical reaction,thereby accelerating the consumption of ozone,and the water vapor content and ozone content are simultaneously reduced,showing a positive correlation in the stratosphere.(5)Backward tracking of water vapor during a heavy rain in Lhasa found that there were three water vapor channels for the heavy precipitation,namely the southern channel originating in the Bay of Bengal,the northeast channel in the upper reaches of the Yangtze River basin,and the northwest channel in the northwest of the plateau;Among the channels,the southern water vapor channel has the largest contribution to the water vapor transported by this precipitation,with the largest number of air masses,accounting for 66.15% of the total;and the changes in height and humidity in the three channels are most obvious during the transportation.By continuing to track forward the water vapor over Lhasa,it was found that the water vapor continued to be transported in three directions,namely the western channel(25%),the northeast fold to the southwest channel(34.38%),and the southern west fold channel(40.63%);Water vapor in the channel with a higher initial height is mainly transported in the zonal direction,and two tracks with a lower initial height can bring water vapor to the upper troposphere and even higher.(6)Tracking the water vapor transport throughout the summer of 2018 in Lhasa found that there are three main channels of water vapor,namely the eastern channel(52.11%),the western channel(25.68%),and the west-folded channel(22.11%)after transportation along the southeast edge of the plateau The first channel has the greatest impact on precipitation in eastern China;the height and humidity of the western channel change the most gently,and the other two channels have more consistent trends,but all three can transport water vapor from the troposphere and the top of the troposphere from different heights. |
PDF Full Text Request