Monitoring And Retrieving For Inhomogeneous Atmospheric Ducts Based On WRF And Weather Radar Data

The electromagnetic wave will form abnormal propagation in the tropospheric duct environment, and the performance of radar and wireless communication equipment are badly influenced by the abnormal propagation characteristic of electromagnetic wave, so it is meaningful to monitor the atmosphere refraction environment for researching the propagation characteristic of electromagnetic wave. The atmosphere refractive index is determined by meteorological parameters, whose variety leads the complexity of the atmosphere refractive index. It is expensive and time-consuming to measure the atmosphere refractive index directly, so a low cost and real time monitoring method for atmosphere refractive index is needed. At present, the Refractivity from Clutter(RFC) method is widely used, and the retrieving optimization arithmetic is fleetly developed. The mesoscale WRF model could obtain the atmosphere environment parameters and assimilate regular observation data, and it becomes an effective tool for monitoring atmosphere refractive index. This paper combines the mesoscale model with RFC method, which obtains relatively exact atmosphere refractive index.The Doppler weather radar is introduced and the changing characteristic of electromagnetic wave with time and space is analyzed based on the echo figure of Doppler weather radar in Qingdao weather bureau. The echo distribution characteristic of Doppler weather radar is analyzed according to different elevation, and the influence of atmosphere duct environment for electromagnetic wave propagation is farther validated.The atmosphere modified refractivity and evaporation duct height are simulated based on mesoscale WRF model, and the advantages of four parameters model than PJ model of evaporation duct are expatiated. Then the simulated atmosphere refractivity is used as input, and the maritime area echo of Doppler weather radar is simulated based on the electromagnetic wave propagation PE model, radar weather equation and Doppler weather radar parameters. Finally, the simulated echo power and reflectivity factor are compared with measured data, which indicates that the simulated Doppler weather radar echo agrees well with measured data. It is relatively effective for the mesoscale WRF model to simulate meteorology parameters, and the foundation is founded by simulated atmosphere modified refractivity for the modeling and retrieving of atmosphere refractivity profile.The atmosphere modified refractivity is retrieved based on the RFC method, and the using measured data is Doppler weather radar echo power data. The horizontal inhomogeneous atmosphere duct modified refractivity profile parameter model is modeled by Principal Component Analysis(PCA) method, then the profile parameters are sampled by Particle Swarm Optimization(PSO) algorithm, finally the atmosphere modified refractivity profile is obtained based on the retrieving model.The profile parameters are fleetly sampled by Markov chain Monte Carlo sampling method and the posterior probability density distribution of retrieving profile parameters is calculated based on the Bayesian posterior probability density estimation theory. The uncertainty of retrieving result is analyzed as the retrieving profile is obtained. Finally, the atmosphere modified refractivity simulated by WRF model is used as transcendent information to modify the retrieving result. The result indicates that the Bayesian retrieving result is relatively exact, and the certainty is enhanced when transcendent information is added, which indicates the reliability of WRF model for monitoring and retrieving the atmosphere refraction environment.