Relationship of rainfall rate and radar reflective in east Georgia

Abstract

Because the Country territory is prone to flash floods and mudflows, Quantitative Precipitation Estimation (QPE) and Quantitative Precipitation Forecast (QPF) on any leading time are very important for Georgia. Weather ground radar is the main tool for now-casting and very short-range forecast. Two such radars operate in eastern Georgia. In this study, we presented calibration results one of them, which located in the Kakheti region. Precipitation estimation was compared to measured rainfall on 10 automated rain gauges within the radar coverage area. The calibration time step is an hour with the analysis period of 2017-18. We divided data into two subsets. The first set of 300 pairs with rainfall intensity from Georgian NHMS rain gauges network was used to cali-brate the Z-R and to obtain parameters by minimizing RMSE and mean bias. The second set of 450 members was used for vali-dation. The corresponding Z-R relationships for this region is Z = 148R1.5. The minimization of mean root square errors between the rain gauge and the radar-derived measurements of rainfall shows significant improvement of radar estimated precipitation after the calibration of Z-R dependence.