Abstract
Ground clutter caused by variations of atmospheric refraction environment can occur when the weather radar is observing precipitation systems, especially in the presence of a tropospheric duct. Therefore, the acquisition of duct parameters is very important for evaluating radar performance and improving data quality. Based on the measured echo data of a Doppler weather radar located at Qingdao and the numerical simulation results of modified refractivity profiles from the Weather Research and Forecasting (WRF) model, an inversion method for regional range-dependent tropospheric duct parameters over the sea area is proposed in this paper. Due to the higher antenna height of up to 169 m, the transmission environment is assumed to be a surface duct with a base layer for locating the antenna in the trapping layer. The Principal Component Analysis (PCA) and Parabolic Equation (PE) methods were used to characterize the horizontal inhomogeneity of duct parameters and the propagation of electromagnetic waves in the tropospheric duct. In the inversion model, duct parameters extracted from WRF outputs were used as the initial values. Additionally, multithread parallel processing was adopted in order to reduce the inversion time based on the characteristics of the optimization algorithm. The overall variation tendencies of the WRF simulation results in the regional distribution of duct parameters were well consistent with the inversion results, but were relatively lower in terms of specific values. Due to the influence of precipitation targets on measured echo data, the inversed echo data had different agreements with the measurements in space, and the absolute error values were less than 5 dB in about 90% of the region of interest.
Highlights
Variations in meteorological conditions in the atmospheric boundary layer have serious impacts on the performance of radio equipment operating in the lower atmosphere [1,2]
The Weather Research and Forecasting (WRF) model is a mesoscale numerical weather prediction and atmosphere simulation system designed for research and operational applications, principally developed and maintained by the Mesoscale and Microscale Meteorology (MMM) Division of the National Center for Atmospheric Research (NCAR), the National Centers for Environmental Prediction (NCEP) and the Earth System Research Laboratory (ESRL) of the National Oceanic and Atmospheric
Based onofmeasured echo data of a Doppler weather radar located at Qingdao, the regional distributions tropospheric duct parameters over thethe sea area around thethe radar is is estimated in in this distributions of tropospheric duct parameters over sea area around radar estimated this distributions of tropospheric duct parameters over the sea area around the radar is estimated in this paper
Summary
Variations in meteorological conditions in the atmospheric boundary layer have serious impacts on the performance of radio equipment operating in the lower atmosphere [1,2]. The base of a bilinear refractivity profile sea clutter power and duct parameters is very complicated, and the inversion process can be with linear range dependency using a maximum a posteriori method [31]. The inversionparameters, problem can be solved through the use of Firstly, the regional of the meteorological vertical modified refractivity profiles, and tropospheric ducts over the ocean area of interest at a given point intelligence, can be obtained from optimization algorithms, whereby optimization algorithms based on swarm such as Ant the outputs of the WRF model.
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