Comparative Evaluation of Some BOMEX Measurements of Sea Surface Evaporation, Energy Flux and Stress

Abstract

The Sea-Air Interaction Program, or ?Core Experiment,? of BOMEX ruled the layout of the ship array, scheduling of observations, and deployment of aircraft during the first three BOMEX observation periods: 3?15 May, 24 May?10 June and 19 June?2 July, 1969. It was designed to provide data on the sea-air flux of energy by three methods: 1) measuring atmospheric budget terms over a 500-km square; 2) direct measurement of surface-layer vertical eddy fluxes at various times and places within the square; and 3) measuring the major terms of the heat budget of the upper ocean at each of the ship stations. The momentum flux was also to be evaluated by the first two methods. After a long period of data reduction, some estimates of the evaporation rate, stress, sensible heat flux, and kinetic energy flux have now been obtained by each of the methods. Preliminary estimates of the evaporation rate are typically about 5?6 mm day?1. The Bowen ratio was about 0.1 for microscale measurements and less than 0.09 for the average fluxes over the 500-km square under undisturbed tradewind conditions. Water vapor appears to play the key role in the dynamics of the atmospheric boundary layer under these conditions.