Evolution of mass transport between the eye and eyewall of Hurricane Guillermo (1997)

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Wednesday, 18 April 2012
Evolution of mass transport between the eye and eyewall of Hurricane Guillermo (1997)
Heritage Ballroom (Sawgrass Marriott)
Matthew D. Eastin, University of North Carolina at Charlotte, Charlotte, NC; and P. Reasor

Several theoretical, numerical, and observational studies have suggested that coherent mesovortices along the eye-eyewall interface can play a significant role in modulating the azimuthal distribution of eyewall convection as well as overall hurricane intensity. In particular, enhanced ascent can occur in those regions where mesovortex-induced outflow converges with the low-level inflow. Furthermore, the export of any high entropy air from the low-level eye into the (relatively) low entropy eyewall can generate transient, buoyant, convective-scale updrafts. Some recent studies have argued that such entropy injections can produce “super-intense” systems (in terms of their steady-state maximum potential intensity). In contrast, other studies have argued that such injections play a minimal role in determining the maximum intensity.

Using an extensive dataset consisting of 20 unique dual-Doppler wind analyses from Hurricane Guillermo (1997), we attempt to elucidate the extent, evolution, and impact of mesovortex-induced mass transport between the low-level eye and eyewall during (a) an initial period of rapid intensification and (b) a second steady-state period near maximum intensity. The mass transport between the eye and eyewall is documented through a census of forward (backward) air parcel trajectories initialized in the low-level eye (mid-level eyewall) during each Doppler analysis. A synopsis of our results and their comparison with previous numerical studies will be presented at the conference.