The Relationship Between Reflectivity and Rainfall Rate From Rain Size Distributions Observed in Hurricanes

Raindrop size distributions collected by the DROPLET MEASUREMENT TECHNOLogies Precipitation imaging probe from 17 flights through 6 hurricanes during National Oceanic and Atmospheric Administration's hurricane field program in 2020 are used to study reflectivity (Z) and rainfall rate (RR) (R) relationship (i.e., Z-R relationship). The results show that the Z-R distribution is highly scattered and the scatter increases with RR and reflectivity up to 48 dBZ or 25 mm hr(-1), after which it decreases rapidly. The range of the estimated RR from a power-law Z-R relationship can be as large as 50 mm hr(-1) at reflectivity of 40 dBZ. The result from random forest regression model demonstrates that including the information of mass-weighted-diameter (D-m) along with radar reflectivity improves the estimated RR significantly.