Study On The Method Of Doppler Radar Base Data Quality Control

With the development of computer technology and the advances in numerical weather forecast model, it is possible to have high resolution data of radar applied to numerical forecast model to improve the numerical forecast. But the base data of the Doppler radar is not always correct, affecting the application of radar data in business. Therefore, the quality control of radar base data would have great significance. Nowadays, the radar base data is influenced by three problems:(1)distance folding;(2)velocity aliasing;(3)clutter. Dealiasing and removing clutter is the main work in this paper.The basic idea of the dealiasing algorithm for the Doppler radar radial velocity can be divided into two steps:the first step is to determine the reliable observations; the second step is the continuity check based on the reliable observations. Generally, we have two methods to determine the reliable observations, one is to contrast radar radial velocity with another observational or non observational meteorological data; the other is obtain them from the radar radial velocity observations themselves. We can obtain reliable observations from the radar data by means of tangential method and radial method. I fulfilled two dealiasing algorithms with fortran computer language, one obtains reliable observations by means of tangential method and the other is by means of radial method. Additionally, this paper designs and made makes simulated Doppler radar radial velocity data, which is used to test two typical automated dealiasing method. According to the result, the two methods are both very sensitive to the characters of the wind. The dealiasing algorithm which obtains reliable observations based on tangential method performances very bad when nonlinearity of the wind is strong. The other dealiasing algorithm do not performance well when the isanemone of the radial velocity data is not match to radar radial line. Then, a new dealiasing method obtains reliable observations based on radial method has being designed based on the two methods. The new method is more robust according to the testing result.The other main work of this paper is to remove AP clutter. This paper tested the method offered by Kessinger with real Doppler radar observations. According to the result, there are two defects in the original method which just uses the result from APDA to remove AP clutter. One is that it would remove meteorology echo falsely and the other is that it almost do anything when there are no Doppler information. So, this paper combines two echo identification algorithms (APDA, PDA) based on the method offered by Kessinger, which would ensure that the meteorology echo would not be removed falsely; and a kind of experienced method to be supplemented when there is no Doppler information.