Impact of Antecedent Land State on Post Landfall Tropical Cyclone Sustenance

Location: FL 2 - Room 1001
Subashini Subramanian, Purdue University

Although a favorable synoptic environment is the most important factor in the maintaining a tropical cyclone and the upward transfer of enthalpy fluxes from the ocean surface to the atmosphere and the downward transfer of momentum from the atmosphere to ocean surface eventually controls the evolution and intensification of a Tropical Cyclone (Anthes and Chang 1978; Emanuel 1995; Ooyama 1969; Tuleya and Kurihara 1978), several TCs are known to sustain over land and some of them have even been found to intensify over land. Tropical Storm Erin (2007) and Tropical Cyclone Abigail (2001) are two examples. Given that most of tropical cyclone’s impact is felt on land – Rainfall, inland flooding, storm surges, wind damage etc., understanding the problem of sustenance/ re-intensification of tropical cyclones over land is not only important but critical to plan, coordinate and execute mitigative efforts.
Lack of significant latent heat transfer into the hurricane boundary layer is cited as the typical cause of cyclone post-landfall decay. In this talk, the impact of warm and wet land surfaces on tropical cyclone post-landfall evolution using an idealized version of the Hurricane Weather Research and Forecast (HWRFX2013) model will be presented. Results indicate that warmer surfaces are necessary to sustain a storm over land and a wet land surface enhances sustenance. These findings were further analyzed using a quasi-operational, non-idealized modeling study of tropical storm Erin (2007) that intensified post landfall. Results help clarify that the sensible heat flux and resulting enthalpy can be more important than latent heat flux and wet land surfaces alone, in terms of causing an environment favorable for post landfall storm sustenance.