Performance Evaluation of Polarimetric Radio Occultation Measurements in Detecting Precipitation

Abstract

For the first time, ROHP-PAZ mission is using polarimetric radio occultations measurements to estimate precipitation. This paper evaluates the performance of the averaged vertical profiles of the integrated differential phase shift ΔΦ in detecting precipitation above a certain threshold. Using IMERG precipitation products as target, I developed an algorithm that computes the F1 Score for several averages between different heights ho and hf . I found that the optimal range for computing these averages starts at ho <∼ 1 km and reaches hf between 5 km and 10 km. These averaged profiles achieve F1 Scores ranging from 0.4 to 0.6 depending on the precipitation threshold. Moreover, the results show that the optimal range of heights for computing the average shifts to higher altitudes when studying tropical regions. This could be due to higher levels of noise registered near the surface at low latitudes and to the vertical structure of convective precipitation which is predominant in these regions.