A probabilistic model for estimating ocean-spray distribution in extreme tropical cyclone winds

Abstract

ABSTRACT. Serious gaps in knowledge about ocean spray at wind speeds over 28 m/s remain difficult to fill by observation or experiment; yet refined study of the thermodynamics of Tropical Cyclones (including typhoons and hurricanes) requires assessment of the hypothesis that ‘spray cooling’ at extreme wind speeds may act to reduce (i) the initial temperature of saturated air rising in the eyewall and so also (ii) the input of mechanical energy into the airflow as a whole. Such progressive reductions at higher speeds could, for example, make any possible influence, of future global warming on Tropical Cyclone intensification largely se1f-limiting. In order to help in extrapolation of knowledge on ocean spray to extreme wind speeds, a probabilistic analysis is introduced which allows for the effects of gusts, gravity and evaporation on droplet distributions yet all other respect is as simple as possible. Preliminary indications from this simplified analysis appear to confirm the potential importance of spray cooling.