Capture and Characterization of Near-Surface Wind-Driven Rain during Hurricane Ike (2008)

This paper presents the results of a field study conducted during the landfall of Hurricane Ike (2008) to characterize near-surface wind and wind-driven rain simultaneously throughout the passage of a hurricane eyewall.

The principal experimental challenge of this research was developing an observational system capable of accurately quantifying raindrop size in the presence of strong winds (> 20 m/s). The solution was to adapt a two-dimensional, aircraft-mounted Droplet Measurement Technologies (DMT) Precipitation Imaging Probe (PIP), with a diode resolution of 100 micrometers, for ground-based measurement. The PIP was mounted to a two-axis turret located at 3m on an instrumented tower collecting high-fidelity measurements of 3D wind velocity at 5 m and 10 m. The turret's mechanical system was actively controlled by an onboard computer monitoring the 5 m wind speed and direction in real-time to determine the azimuth and elevation angle of the instantaneous rain vector.

The system was deployed successfully in Baytown, Texas during Hurricane Ike (2008). Simultaneous measurements of 3D wind velocity and wind-driven rain were collected leading up to and through the eyewall passage. This paper provides details on the experimental configuration and presents results on raindrop size distribution, reflectivity, rainfall intensity, total concentration and liquid water content. Additionally, reflectivity and rainfall measurements are compared to remotely sensed estimates from the National Weather Service WSR-88D Doppler Radar KGHX.