The fall speeds and ice water paths of small and large ice species in Hurricane Arthur (2014)

In the past decade, dual-polarization radar measurements have been used extensively to infer the types, sizes, and concentrations of liquid and frozen hydrometeors in severe thunderstorms. However, comparatively little work has been undertaken in tropical cyclones (TCs), despite the influence that the particle size distribution may have on the thermodynamic fields that affect TC dynamics and air-sea fluxes. Hurricane Irene (2011), which made landfall near Cape Lookout, North Carolina (NC) as a 75-kt hurricane, represents an ideal opportunity to use the dual-polarized Weather Surveillance Radar–1988 Doppler (WSR-88D) in Morehead City, NC to study TC microphysics. We will present radial and altitudinal distributions of the dual-polarization radar variables, including reflectivity (Z), differential reflectivity (Z_DR; proportional to particle axis ratio), and specific differential phase (K_DP; proportional to rain rate) to describe the hydrometeor characteristics of Hurricane Irene. Further, the ice mass distribution, derived from the WSR-88D hydrometeor classification algorithm, will be presented and used to infer the ratio of precipitating to non-precipitating ice. Remote observations of ice microphysics in TCs are particularly valuable, since aircraft reconnaissance missions are not currently flown above the melting layer. Such results may be used to validate TC model microphysics schemes, which have traditionally struggled to reproduce expected diameters and mass concentrations of non-precipitating ice.