Inflow Layer Energetics of Hurricane Bonnie near Landfall

The mean equivalent potential temperature (qe) of the hurricane inflow layer has been shown to have a large impact on hurricane intensity, but quantifying the processes that affect qe in the inflow layer has been extremely difficult. On August 26, 1998 a USWRP experiment was conducted with the NOAA WP-3D's in Hurricane Bonnie (965 mb) as it approached Cape Fear, N.C.. Curved tracks of approximately 200 km were flown in an attempt to sample the inflow trajectory of the low level air. The aircraft flew above the inflow layer, which was typically 1400 to 1500 m deep, and deployed 55 GPS sondes. Several trajectories were sampled which provide a view of the inflow air from various underlying source regions, such as the continental U.S., Gulf Stream, and the upwelling region in the storm's wake. Radar reflectivities in Bonnie reveal a complex eye wall structure where rainbands merge with eyewall convection. Initial findings indicate that downdrafts from rainbands affect qe and potential temperature (q) nearby. Where rainbands are not present, low level q and qe are better mixed, and the trajectory appears to be nearly isothermal. Ultimately, the energy budget of the inflow layer with flux estimates at the air-sea interface will be diagnosed.