Rain Characteristic Revealed with the Polarimetric Radar

摘要

Polarimetric Doppler radars provide an impressive experience to remotely observe the internal motions in convective storms and infer precipitation types as well as amounts. The emphasis herein is on measurements of rain. Hence, a review of recent results on relations between drop size distribution parameters is given. A description of the preferred technology for polarimetric weather radars follows. Polarimatric variables are introduced and propagation issues affecting polarimetric measurements are discussed. It is demonstrated that the relations between the polarimetric variables and rainfall yield superior estimates. Ways to restore attenuated signals are broth forth; application of these produces, at short wavelengths, estimates of unprecedented accuracy. Ample examples illustrating advantages of rain measurements with polarimetric radar are given. Overall the accuracy of polarimetric method is two to three times better than the accuracy of the method that relies only on reflectivity. Undisputed advantage of polarimetry is its discriminatory power to separate rain echoes from artifacts thus providing measurements where it is raining. A great untapped potential for retrieving parameters of the drop size distribution is also demonstrated.