Microphysical Characteristics of an Asymmetric Eyewall in Major Hurricane Harvey (2017)

Microphysical and kinematic structures of major Hurricane Harvey's (2017) asymmetric eyewall are analyzed from ground‐based polarimetric and airborne Doppler radars. New polarimetric observations of differential reflectivity ( Z DR ) and specific differential phase ( K DP ) show asymmetric wavenumber‐1 patterns associated with vertical wind shear (VWS) but were shifted azimuthally with respect to the reflectivity ( Z H ) asymmetry. A Z DR column was found upwind of the Z H maximum in a region with strong updrafts estimated from multi‐Doppler synthesis, with higher values of K DP found cyclonically downwind. Retrieved raindrop size distributions show that azimuthal variations of size and number concentration were determined by both the VWS and the size sorting process. The diameter of raindrops decreases, while the number concentration increases cyclonically downwind of VWS‐induced updrafts due to the differential terminal fall speed of raindrops and strong rotational flow at major hurricane wind speeds.