Viscous Heating in Hurricanes

The effect of internal energy rise (temperature) due to irreversible viscous heating by turbulent rate of dissipation is addressed through surface-layer approximations and parameterizations of the Brinkman (Br) and Eckert (Ec) dimensionless numbers. The Brinkman number is the ratio of the viscous heating to that from sensible heat transfer at the ocean surface. The Eckert number characterizes the viscous heating effect on the temperature rise within the surface layer. Parameterization formulas for Br and Ec are developed in terms of mean wind speed and sea-air temperature difference. Br=1 is the value at which the viscous heating effect equals that from surface heat transfer and occurs at 37 m/sec for 1K sea-air temperature difference. Ec=1 is the value at which the temperature gradient at the surface becomes zero, suppressing heat transfer, and occurs at 45 m/sec for 1K sea-air temperature difference. For Ec>1, sensible heat is actually transferred from the air to the ocean. The analysis gives quantitative estimates of the effects of viscous heating in hurricanes. Supported by the Office of Naval Research, Marine Meteorology.