Observational and modeling comparison of Super-Typhoon Jangmi (2008) and Hurricane Katrina (2005)

Airborne Stepped Frequency Microwave Radiometer (SFMR), GPS dropsonde, Airborne Expendable BathyThermograph (AXBT), air-deployed drifting buoy, land-based and airborne radar and satellite microwave observations from the TCS08/ TPARC field experiment are used to document the intensity and structure changes of Super-Typhoon Jangmi as it traversed across warm and cold ocean eddies of the WPAC ‘Southern Eddy Zone' prior to landfall on Taiwan. Rapid Intensification (RI) was followed by Rapid Filling (RF) following a sequence of eyewall replacement cycles and accompanied by a dramatic change in rainband structure prior to landfall. This period was simulated with the air-sea coupled COAMPS-TC mesoscale model. The model simulation showed a 12-18 hour delay in TC filling, in agreement with previous observational and modeling studies, rather than the observed immediate RF response to passage over the eddy boundary. It is suggested that entrainment of dry air from downdrafts associated with an unusually active pre-typhoon squall line ahead of Jangmi, documented by Taiwan land-based radars, may have produced an additional, and more immediate, negative impact on TC intensity change prior to onset of landfall-related RF. We suggest that a similar, but somewhat more complex sequence of events may have been associated with the RI and RF events related to major structure changes prior to the landfall of Hurricane Katrina observed during the IFEX05/RAINEX field experiment as the TC traversed the boundary between the deep/warm Gulf Loop Current and the shallow/cold shelf water, documented recently by B. Jaimes and L. K. Shay (U.Miami/RSMAS). The Katrina coupled COAMPS-TC simulations showed a TC filling response lag of 8-12 hours to the underlying ocean structure change, similar to the lag simulated for the Jangmi case. This suggests another factor, as yet unidentified, that must have been acting simultaneously to produce the observed immediate and rapid TC intensity and structure changes prior to landfall-induced effects.