| Using 1979-2018 MSR2(Multi sensor reanalysis)to reanalyze the monthly average of total ozone data,the temporal and spatial evolution of the total ozone over the Qinghai-Tibet Plateau and the variation characteristics of the ozone trough intensity were analyzed.Further use the 2m temperature reanalysis data and CRU monthly average precipitation data provided by the European medium-term numerical forecast center ERA-interim,and use the empirical orthogonal function decomposition(EOF)method to analyze the spatial and temporal evolution of the temperature and precipitation in the Qinghai-Tibet Plateau and its surrounding areas Were studied.Combined with the physical height,latitude wind,meridional wind,vertical velocity,specific humidity and other physical quantities provided by the European medium-term numerical forecast center ERA-interim,and the heat fluxes such as sensible heat,latent heat,net long wave radiation,net short wave radiation,etc.Analyze the data,study the possible effects and mechanisms of ozone changes on precipitation and temperature in the Qinghai-Tibet Plateau and its surrounding areas through comparative analysis and synthetic analysis,and draw the following main conclusions:(1)The distribution of total ozone over the Qinghai-Tibet Plateau has obvious latitudinal features,and there are also obvious seasonal changes,more in winter and spring,and less in summer and autumn.The change trend of the total ozone over the Qinghai-Tibet Plateau in different periods is different.Between 1979 and 1998,the total ozone showed a decreasing trend,and between 1999 and 2018,the total ozone showed an increasing trend.In 2018,the total amount of ozone on the Tibetan Plateau showed a decreasing trend.The maximum value of total ozone over the Qinghai-Tibet Plateau occurs in March each year,while the minimum value occurs in October each year.The total amount of ozone over the Qinghai-Tibet Plateau has significant periodic oscillations of quasi-2-3 years,quasi-four years,and quasi 8-11 years.(2)The maximum value of total ozone in the mountainous area at the same latitude occurs in April,and the minimum value occurs in November.The total ozone over the Tibetan Plateau is lower than the mountainous area in the same latitude zone throughout the year The month(except October)shows a downward trend;the difference between the total amount of ozone over the Tibetan Plateau and the mountainous area at the same latitude indicates the intensity of the ozone trough on the Tibetan Plateau.In summer and autumn,the trend is slowly weakening,and in winter and spring,it is increasing.(3)The first eigenvector field of the anomalous temperature field presents a positive signal that is consistent throughout the region,indicating that the temperature changes in the Qinghai-Tibet Plateau and its surrounding areas are less regional.The Qinghai-Tibet Plateau and its surrounding areas have shown a trend of warming in the past 40 years,and there is a further upward trend.The spatial distribution of the second eigenvector field shows a reverse change from north to south.In addition to the uniform change in the entire region,the temperature changes on the Qinghai-Tibet Plateau and its surrounding areas also have certain regional differences.The first eigenvector field of the precipitation anomaly field basically shows a positive signal that is consistent throughout the region,indicating that the regional variation of precipitation in the Qinghai-Tibet Plateau and its surrounding areas is small.The precipitation over the Qinghai-Tibet Plateau and its surrounding areas has shown no obvious trend in the past 40 years.(4)In the summer when the ozone is abnormally high,the precipitation in Sichuan and western Yunnan is higher than the average for many years,and the precipitation in the south of the plateau and the southeastern plateau is lower than the average for many years.Combined with the analysis of the difference characteristics of the atmospheric circulation field in the year of ozone anomaly,at 850 h Pa,China's South China,Southeast and most parts of the South China Sea have a high potential,and there is an anticyclonic circulation over the area;in Arabia The potential height of the sea area is small,and there is a cyclonic circulation over the area;at 500 h Pa,the anticyclonic circulation at 850 h Pa is enhanced,while the cyclonic circulation is weakened and an anticyclonic circulation appears;at 200 h Pa,the cyclonic circulation always exists,which enhances the southwest airflow through the Bay of Bengal and through the Indochina Peninsula to the southwest,which provides favorable conditions for the formation of precipitation in the southwest.It can be obtained from the vertical velocity field that the airflow in the middle and upper levels of Sichuan,most parts of Yunnan and the southeastern plateau shows a strong upward movement,indicating that it is conducive to precipitation,and the airflow in the south of the plateau shows a strong sink Exercise shows that it is not conducive to precipitation.Combined with the water vapor transport field,except for the Sichuan Basin,the water vapor flux divergence in the southwest region is lower than the average for many years,there is obvious water vapor convergence,and the water vapor flux transported from the southwest to the southwest region is stronger,indicating that There is too much precipitation in this area;and there is water vapor divergence in the plateau and the area south of the plateau,indicating that the above area has less precipitation.The situation in the summer when the ozone difference is low is basically opposite to that in the strong year.(5)During the summer when the ozone is abnormally high,the temperature in most areas of Sichuan,Chongqing,Guizhou,and Xinjiang is lower than the average for many years,and the temperature in the plateau and south of the plateau and Yunnan is higher than the average for many years.Results The analysis of heat flux distribution characteristics shows that in higher years,the latent heat,sensible heat,net long wave and net short wave radiant flux in Sichuan and Chongqing are higher than the average for many years,while the latent heat,sensible heat,net long wave and The net short-wave radiation flux is lower than the average for many years,and the summer of the abnormally high ozone year is basically opposite to that of the low year. |
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