The Influence of Mesoscale Features of the Sea Surface Temperature Distribution on Marine Boundary Layer Winds off the Scotian Shelf during the Superstorm of March 1993

Abstract

This paper studies the mesoscale wind field during the blizzard of March 1993 off the east coast of North America and examines the influence of the sea surface temperature distribution on surface winds. Can the Gulf Stream and its meanders, by its strong influence on the marine boundary layer, generate mesoscale features in the wind field? Numerical simulations of the storm are carried out using the MC2, a fully elastic nonhydrostatic model. Simulations are conducted at different resolutions (50, 25, 10, 5, and 2 km) with both detailed and smoothed SST fields, so as to examine the influence of these parameters on the marine boundary layer winds. Results from these numerical simulations are compared with surface observations from buoys. The study reveals some mesoscale features in the wind field caused by the Gulf Stream?s meanders and the warm eddies of the SST field. In a stable boundary layer, the meanders shaped a 50?55-kt (26?28 m s?1) band of winds in a general 40?45-kt (21?23 m s?1) wind field. Behind the cold front, local enhancements of 10-kt (5 m s?1) winds were found over the warm water eddies in the unstable boundary layer.