Analysis of Surface Fluxes in the Marine Atmospheric Boundary Layer in the Vicinity of Rapidly Intensifying Cyclones

Abstract

A mooring with a surface buoy was deployed about 300 km southeast of Nova Scotia during the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) in an attempt to obtain long-term, high-quality measurements of meteorological and near-surface oceanographic data. The acquired surface data included sea surface temperature, air temperature, relative humidity, barometric pressure, wind velocity, incident solar radiation, and downward longwave radiation. A limited time series of sea temperature and current velocity was gathered from current meters at 20 and 50 m beneath the sea surface. The surface meteorology was described before, during, and after the passage of three rapidly intensifying cyclones. Estimates of the surface air-sea heat fluxes, computed from bulk aerodynamic formulas, were also examined for these same storms. A simple heat budget was used to estimate the heat loss or gain of the upper ocean against the air-sea heat transfer at the ocean surface. While the total surface heat flux may sometimes exceed 1000 W M?2, the data suggest that the main mechanism for cooling the upper-ocean water was principally advective. An examination of the air-sea momentum transfer shows that the atmosphere exerted a significant influence on the upper ocean; persistent westerly winds coming off the North American continent transported surface waters to the south.