Hurricane Karl's (2010) Warm Core Evolution: An Investigation of Inner Core Thermodynamic and Convective Properties

Hurricane Karl (2010) rapidly intensified from a 45-knot tropical storm into a 105-knot major hurricane in less than 24 hours. Modest intensification was anticipated by the National Hurricane Center and numerical models prior to Karl traversing the Bay of Campeche, however, none of the aforementioned predicted RI. During this period, an unprecedented 6 aircraft examined the inner core and surrounding environment of Karl simultaneously. This collaborative effort between NOAA, NASA (GRIP), and the U.S. Air Force included flights with a P-3, C-130s, DC-8, WB-57, G-IV, and Global Hawk. These aircraft completed a combined 46 center passes at altitudes varying from 850 hPa to above storm level during a 22-hour period. The various instruments aboard the aircraft provide one of the most concentrated datasets (temporally and spatially) for any RI period of any storm in history. The dataset includes the following: Lightning Instrument Package (LIP), High Altitude Imaging Wind and Rain Profiler (HIWRAP), High Altitude MMIC Sounding Radiometer (HAMSR), Airborne Precipitation Radar Dual Frequency (APR-2), Hurricane Imaging Radiometer (HIRAD), and P-3 Tail Radar. In addition, the aircraft reconnaissance data (includes the release of 92 dropsondes) affords an extensive in-situ dataset.

With 20 consecutive overpasses of Karl's center, the Global Hawk flight on 16 September provides a unique opportunity to investigate the temporal evolution of convective and thermodynamic properties within the inner core of a rapidly intensifying tropical cyclone. The thermodynamic properties are closely examined using HAMSR, a 25-channel cross-track scanning microwave sounding radiometer with frequencies near 60, 118, and 183 GHz. We use retrieved products from HAMSR, notably vertical profiles of temperature, water vapor, and relative humidity. We also examine the convective asymmetries and changes with respect to the thermodynamic evolution of the warm core concurrent with intensification.