Comparison Of The Raindrop Size Distribution Retrieval By Wind Profiler And Dual-polarization Radar

Raindrop Size Distribution (DSD) has been defined as the distribution of raindrops concentration per unit volume along raindrop diameter, Different types of precipitation presents different forms of DSD, and it can be described by M-P and Gamma distribution. Following the development of measuring technique, the observation methods of DSD has developed greatly. In the paper, Profiler and Dual-Polarization radar are used to retrieve DSD, and complete the comparative study with the DSD observed by Disdrometer.In paper, the data observed by Disdrometer can been changed into DSD, and the DSD is used to compare with the DSD retrieved by remote sensing facility as the factual DSD. As the Gamma distribution can describe the DSD better, so the Order-Moment-Method is used to fit the factual DSD, then the parameters of DSD base on Gamma distribution has been completed, at last the paper established the function between DSD parameters. Including the function between shape factor mu and scale factor lambda, shape factor mu and scale factor lambda Multiply with equivalent diameter Do, concentration parameter Nw and water content with equivalent diameter Do, these functions can be used to retrieve the DSD.Dual-Polarization radar observe more parameters than conventional radar, can complete the retrieval of DSD based on Gamma distribution better. X-band Dual-Polarization radar working with shorter wavelength, it is easy to be attenuated by the rain, and the paper correct the rain attenuation by Self-Consistent method with constraints. The algorithm makes use of phase without attenuation, such as ΦDP, to correct the reflectivity and differential reflectivity. To correct the RHI and PPI data, and the result shows this algorithm can restore reflectivity and the position of the rainfall centre greatly. Using the function between the data observed by the Dual-Polarization radar and the parameters of DSD can finish the retrieval of DSD, the paper establish the function between radar data and DSD parameters by scattering simulation, and with the function the paper complete the retrieval of DSD by using the data by the radar before and after correction. Compare the retrieved DSD with the factual DSD, the result shows that the data after correction has a better effect. Retrieve the DSD by RHI and PPI data, will show the vertical structure and horizontal distribution of precipitation greatly, and it can be used to study the process of precipitation.The processing of wind profiler data includes Coherent accumulation and Pulse compression in real domain, Noise estimation and peak identification in frequency domain, the power spectrum get after upon the processing contain atmospheric turbulence spectrum and precipitation power spectrum, in the paper the de-convolution has been used to separate the precipitation power spectrum from the turbulence spectrum, and then, using symmetry-subtract-method to get the precipitation power spectrum, finally, the precipitation spectrum is used to retrieve the DSD. Compare the retrieval DSD with the factual DSD, the result shows that the parameters of retrieval DSD are greatly consistent with the factual. In addition, the vertical data of wind profiler can be used to retrieve the profile of DSD parameters, the profile will be used to analysis the vertical structure of precipitation.Compare the DSD retrieved by Dual-Polarization radar and wind profiler by the spectrum shape parameters and measuring method, the result shows that the spectrum shape retrieved by wind profiler is more similar with factual DSD and the DSD shape by the Dual-Polarization radar is monotonous; they both have error with the fact, but the DSD by wind profiler is smaller; The Dual-Polarization radar can observe in RHI and PPI two ways, it can either observe the vertical structure and horizontal distribution, however, the wind profiler can only observe the vertical profile, so, they both have the advantage and disadvantage.