National Tropospheric Atmospheric Refractive Index Profie Modeling Investigation

As a long-distance target detection device,radar can accurately locate the target in the air.With the continuous improvement of radar technology,the modern radar has been widely applied in all walks of life.But the inhomogeneous atmosphere over the earth has a great influence on the performance of radar.When radar electromagnetic wave propagation in the air,atmospheric scattering and refraction of radio waves will affect the accuracy of positioning and speed measuring.In order to further decrease the measurement error of radar,it is necessary to correct the positioning and velocity measuring error of radar caused by atmosphere.The atmospheric parameters that affect radar radio waves are mainly the atmospheric refractive index on the propagation path of the radio waves,that is,the atmospheric profile.So how to accurately obtain the atmospheric refractive index profile is one of the key factors to determine the accuracy of radar error correction.The main purpose of this thesis is according to the characteristics of the landform and atmospheric environment in China to propose a national atmospheric refractive index profile of real-time prediction method based on spatial interpolation algorithm and build up a database of atmospheric profile model coefficient.This thesis briefly introduces the common atmospheric refractive index model and spatial data interpolation algorithms,then optimizing the profile model and the interpolation algorithm,namely the atmospheric section model and radial basis function method.Then,according to the characteristics of the atmospheric environment in china,the national atmospheric environment is divided in detail with grid method.At the same time,the basic detection data needed by interpolation are preprocessed,and the parameters of atmospheric profile model are calculated and treated with de-outlier value.Then,the interpolation principle of radial basis function is explained,and the atmospheric profile model is interpolated by using radial basis function,and the difference result is analyzed in detail.Next,the relationship between the coefficients of atmospheric profile model and the refractive index of the ground is analyzed,and the regression equations between them are obtained.In this way,the ground refractive index in each grid can be used to predict its air refractive index in real time.Later,the precision of the regression equation is verified and the accuracy of the method is proved.Finally,according to the longitude and latitude of each grid,the equation coefficients of the relation equation between the atmospheric profile model coefficient and the ground refractive index in different months in each grid are sorted out,and a database is established to predict the air refractive index in real time according to the ground refractive index.The research results in this thesis can not only provide accurate atmospheric refractive index profile directly for the rapid correction of radar wave refraction error,but also provide a reference for the forecast or prediction of relevant parameters in China without meteorological stations.