Rainfall Doppler Polarization Radar Measurements

Determination of the relationships between radar signal and intensity of rain is the oldest problem of radar meteorology. Later more sophisticated parameters of rain microstructure and turbulence in rain became available for the deriving from radar returns. The implementation of Doppler-polarimetric radars opens new possibilities to improve the quality of radar measuring intensity and other parameters of rain.The main work of this dissertation is organized as follows:Firstly, the basic characteristics and microstructure modes of the rain are summarized. Meanwhile,presenting theory of weather radar including weather radar equation, measuring of precipitation in radar and some influential factors.Secondly, Doppler radar theory and techniques in meteorology have reached a level of maturity. This chapter attempts to provide the interested reader with a fairly rigorous approach to Doppler radar principles, and some related results are simulated in this thesis.Thirdly, the polarization measurement techniques in meteorology is discussed. Radar polarimetry gives the best and, at least, the simplest possibility to turn from single-parameter to multi-parameter measurements. Some important radar observables are simulated in this dissertation.Lastly, a complex of mathematical models is developed to describe the interaction of radar signal with rain particles.Computer simulation of Doppler-polarimetric spectra of radar signal is done by using these models. In the model considerations are being made of the dielectric permeability, form and orientation peculiarities of the scatterers, their size-distribution, wind and turbulent pulsation characteristics, the beam-scanning effects of the locator. The model gives Doppler spectra at different combinations of linear polarization of transmitting and receiving waves.The combination of Doppler and polarization diversity in weather radar technology enables a detailed study of microphysical phenomena in precipitation. Whereas Doppler measurements give information about the dynamical properties of the phenomena (e.g. wind, fall speed), polarimetry is related to the shape and orientation of the hydrometeors. It opens new possibilities for study of the microphysics and dynamics of precipitation.