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 (C_d) and enthalpy (C_k) exchange 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 feedback and tropical cyclone intensity. We find that the magnitude of ocean cooling increases with storm intensity and C_d. Additionally, the simulated maximum wind speed uncertainty does not necessarily decrease when ocean feedback are considered.