15D.1 A Wave-Induced Negative Feedback between the Stratified Coastal Ocean and Land Falling Tropical Cyclones

Friday, 20 April 2018: 8:00 AM
Heritage Ballroom (Sawgrass Marriott)
Ralf Toumi, Imperial College London, London, UK; and S. Wang and N. Bruneau

Predicting tropical cyclone structure and evolution remains challenging. Particularly, the coastal surface wave interactions with
tropical cyclones have received no attention. Through a series of state-of-the art high-resolution, fully-coupled ocean-wave
and atmosphere-ocean-wave experiments, we show here for the first time that wave-induced mixing is the major driver of
stratified coastal ocean ahead-of-cyclone-eye cooling, influencing the evolution of both the ocean and tropical cyclones. The
presence of a continental shelf leads to a small enhancement of the wind-driven cooling ahead of the cyclone compared to
deep water. However, the wave-induced vertical mixing contribution to the cooling is significantly larger than that caused by
by only the wind. In the fully-coupled atmosphere-ocean-wave mode, the maximum wind speed is weaker and the damaging footprint
area of hurricane-force winds is reduced by up to 50% due to the strong cooling ahead. Including wave-induced dynamics is
essential to improve landfalling tropical cyclone intensity predictions for the highly populated and vulnerable coasts.
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