Use of Disdrometer Data for X-Band Polarimetric Radar Simulation and Tropical Rain Characterization

Natural variations in raindrop size distribution (DSD) were studied for simulated X band radar response from October 2004 to July 2005 (normal no-storm conditions) and during September 15th to 16th, 2004 when the tropical storm Jeanne passed over the island of Puerto Rico. Three types of estimators of rain rates were examined: A classical estimator R(Z_H) and two polarimetric radar estimators R(K_DP) and R(Z_H,Z_DR) . According to simulation results, the normalized errors (NEs) with respect data disdrometer of R(Z_H),R(K_DP) and R(Z_HZ_DR) for all DSD samples in October 2004 to July 2005 data are 40.85%, 14.73%, and 15.83% respectively, while for the tropical storm Jeanne they are 23.39%, 9.35% and 14.53%. The results show that the estimator R(Z_H) is the most sensitive to variations in DSD. Calibrated R-Z relations where developed for X-band for two conditions: storm/no-storm. Data from NASA TRMM satellite and rain gauges, the rain rate per hour was used for pinpointing areas of heaviest rain and for validation.