Velocity Dealiasing On Doppler Radar And The Simulation And Identification Of Wind Shear

Wind shear is one of the severe weather events for aircraft flight, especially, downburst is the most typical wind shear on aircraft flight. Reducing the danger of flight caused by wind shear is the key issue for flight safety. In order to avoid this danger, it should be fully understood the echo structure and characteristics of the downburst. Wind shear identification with Doppler radar data is also an important method for the wind shear warning. The new generation Doppler weather radar is an important tool for the early warning of disaster weather in China. But the base data of radar often appears some quality issues, such as velocity ambiguity, which is one of the main factors that affect application of velocity data correctly, especially the C-band radar, which the wavelength is shorter than the S-band wavelength, but the C-band radar data are more likely the velocity ambiguity. Therefore, we should do some work to eliminate the phenomenon of velocity ambiguity before the data processing. Only to ensure that the data is correct, can guarantee the effective application of the velocity data and reduce losses caused by wind shear.Dual polarization Doppler weather radar is the trend of the development of a new generation, the amount of polarization is mainly used for phase identification, improving estimate precipitation, etc. Located in Nanjing University of Information Science and technology of the C-band dual-polarization radar (referred NUIST-CDP) started using both investment in research and teaching. Combined with polarization parameters on the research on the wind shear, this can identify the echo of the strong convection, rain and other weather disasters occurred in the wind shear areas effectively, and thus improve the method of the disaster weather forecasting in short-impending severe.The main content of this paper is for the Doppler radar radial velocity data and to expand, study of velocity dealiasing, downburst simulating and recognition wind shear are as follows:(1) Desizing velocity for C-band dual-polarization of Nanjing University of Information Science and technology (NUIST-CDP), using the approach of computer interaction, circling and stripping the velocity of ambiguity. Contrasting with the data of the S-band radar (CINRAD-SA) located in Longwang Mountain with the same time and verifying the feasibility of the human-computer interaction.(2) Using MATLAB to simulate three-dimensional structure of downburst, especially the vertical cross-section structure, and combing with the scanning of radar is polar coordinates, so the wind field is projected onto the radar radial, by analyzing the cases, summarizing the spatial structure of downburst.(3) The wind shear is identified by least square method, by changing the fitting window size, combined with the recognition of the region growing, contrasting recognition algorithm. Apply the least square method with piecewise fitting to the data of MUIST-CDP after velocity is dealiased, combined with polarized parameter analysis the data of NUIST-CDP to identify wind shear and the precipitation area in the shear.