Characterizing the Structure of Hurricane Karl (2010) Through Analysis of High-Resolution Doppler Radar Data and Numerical Simulation

Wednesday, 17 December 2014
Jennifer DeHart, University of Washington Seattle Campus, Seattle, WA, United States and Robert Houze, University of Washington, Seattle, WA, United States
Airborne radar data and a series of numerical simulations are employed to investigate the structure of Hurricane Karl (2010). Karl was a strong hurricane that reached its peak intensity in the Gulf of Mexico before making landfall on the mountainous coast of Veracruz, Mexico. Multiple aircraft extensively sampled Karl during the NASA GRIP campaign, including NASA’s DC-8 aircraft instrumented with the Advanced Precipitation Radar 2 (APR-2). APR-2 is a high-resolution, dual-frequency Doppler radar capable of classifying hydrometeor types. Data from APR-2 provide a unique opportunity to characterize the precipitation and microphysical structure of Hurricane Karl over the open ocean and as it underwent orographic modification during landfall.

Analysis of the radar data is complemented by a series of WRF runs, in which different microphysical schemes are employed. In particular, the resulting structures from the simulations are compared to the patterns derived from the APR-2 reflectivity, velocity and hydrometeor snapshots. These comparisons allow for an assessment of the ability of each microphysical scheme to reproduce the observed structure. Consistent with prior studies, it is shown that the vertical and horizontal hydrometeor patterns depend strongly upon the microphysical scheme chosen, despite the relatively similar tracks generated by each model run. Finally, the resulting thermodynamic structures and flow patterns produced by each model simulation are examined to provide information missing from the radar data.