Nonlinear Impacts of Surface Exchange Coefficient Uncertainty on Tropical Cyclone Intensity and Air-Sea Interactions

Tropical cyclone maximum intensity is believed to result from a balance between the surface friction, which removes energy, and a temperature/moisture (enthalpy) difference between the sea surface and the air above it, which adds energy. The competing processes near the air-sea interface are controlled by both the near surface wind speed and the surface momentum (Cd) and enthalpy flux (Ck) coefficients. Unfortunately, these coefficients are currently highly uncertain at high wind speeds. Tropical cyclone winds also apply a force on the ocean surface, which results in ocean surface cooling through vertical mixing. Using coupled atmosphere-ocean and uncoupled (atmosphere only) ensemble simulations we explore the complex influence of uncertain surface exchange coefficients on storm induced ocean feedbacks and tropical cyclone intensity. We find that the magnitude of ocean cooling increases with storm intensity and Cd. Additionally, the forecasted maximum wind speed uncertainty does not necessarily decrease when ocean feedbacks are considered.