Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean Conditions

Abstract

Abstract : Wind-wave interactions are of fundamental importance as they determine the sea surface drag and scalar exchange between the atmosphere and ocean. This is particularly important at high winds since air -sea coupling controls tropical cyclone (hurricane) formation and intensity. There is large uncertainty in the bulk momentum and heat surface exchange coefficients (Cd , Ck) derived from field observations and laboratory experiments for varying wind speed, wave age, swell amplitude and direction, and in the presence of spray, with an even greater debate as to the underlying dynamical processes that couple the winds and waves (Black et al., 2007, French et al., 2007, Powell et al., 2003, Sullivan et al., 2008). In this context, the overarching theme of this project is to identify the physical processes that couple winds in the marine atmospheric boundary layer and the underlying surface gravity wave field at high wind speeds. Th is project seeks to reconcile laboratory and field measurements of wind-wave interaction and surface drag in high to extreme winds using turbulence resolving large-eddy simulation (LES). The basic science question we address is: how confidently can we upscale dynamical processes and measured statistics in small- scale laboratory experiments to full-scale high wind ocean conditions?