Research On The Construction Of Real-time High-precision Vertical Tropospheric Profile Model In China

As the main driving force of weather changes,water vapor is an important factor in the formation and evolution of disaster weather,and also the most active component in the atmosphere.In GNSS meteorology,the tropospheric delay is closely related to the change of water vapor.The fine change analysis of the tropospheric vertical profile delay information can reflect the change of water vapor to a certain extent,which can provide an important reference for disaster weather warning.Traditional tropospheric vertical profile models often use a single linear function,which is difficult to satisfy the precise expression of regional water vapor vertical information.Due to its large north-south span,complex topography,and coexistence of multiple climatic and environmental conditions,the vertical and vertical changes of water vapor information in China are particularly turbulent.The applicability of traditional models in this area is relatively low.Suitable for high-precision tropospheric vertical section models in China.Based on the above problems,first,in the selection of modeling data sources,this article uses the current MERRA-2 product data with higher spatial and temporal resolution;second,in the vertical modeling method,the troposphere is based on Gaussian function and exponential function,respectively The construction of the vertical profile model;then,the respective coefficients of the two function models are analyzed in time series,and the corresponding annual and semi-annual cycle changes are added;finally,a real-time and high-precision Chinese region is constructed that takes into account the characteristics of time and space changes Vertical section model of the troposphere.The main steps and conclusions are as follows:1.Based on MERRA-2 product data,a vertical profile function model of the troposphere in China expressed by Gaussian function and exponential function was constructed.In the vertical direction,three target points in the area are randomly selected for vertical layered data verification;in the horizontal direction,the mean distribution map of the deviation factors of each grid point is drawn.The results show that the tropospheric vertical section delay model based on the expression of Gaussian function in China has higher accuracy and stronger stability than the expression of exponential function,and the adaptability at the sample points in central and southern regions is more prominent.2.Further time series analysis of the correlation coefficients of the two function models.In the vertical direction,analyze the model coefficient time series from 2014 to 2016 at three grid points in China;in the horizontal direction,plot the average distribution of coefficient factors for the entire China region.The results show that the correlation coefficient has obvious annual and semi-annual cycle changes.Adding the seasonal characteristic analysis for this part of coefficients on the basis of the original model can theoretically improve the applicability of the model.3.Constructed a real-time high-precision tropospheric vertical profile model in China that takes into account the characteristics of changes in time and space.Use MERRA-2 data for internal compliance inspection,while using sounding stations and GGOS grid data for external compliance inspection.The results show that the model based on the Gaussian function description has a better applicability than the model described by the exponential function in China as a whole.4.In summary,the model constructed in this paper can provide users with real-time and high-precision tropospheric vertical profile information in time and space characteristics at any altitude in China,and can serve GNSS meteorology,natural disaster warning and other fields the study.