Upper ocean cooling and air‐sea fluxes under typhoons: A case study

Direct observations of ocean temperatures and air-sea energy exchange underneath three typhoons and a tropical storm encountered in the Philippine Sea during the 2010 Pacific typhoon season are examined. Data are reported from two buoys 180 km apart with ocean temperatures recorded to 150 m and wind speeds up to 26 m s(-1). A detailed examination of the cold wakes is used to determine the mechanisms though which the ocean cools. The result show that net cooling varied between storms by two orders of magnitude, accounting for between 9 and 1000 MJ m(-2) of heat loss, and were a result of entrainment, advection, and surface fluxes. In some cases a marked temperature increase below the mixed layer occurred due to entrainment of warm water across the thermocline. Mixed layer temperature decreases ranged from 0.35 to 1.6 degrees C and found to be well predicted by typhoon translation speed and wind speed. Of the mixed layer heat loss, 12-47% was attributed to enthalpy fluxes, the upper range of which is much greater than previous reports. Results are discussed in terms of their relevance to tropical cyclone and climate modeling.