Wind‐forced pressure response of the Gulf of Maine

Bottom pressure measurements, coastal synthetic subsurface pressures, and wind stresses, derived from operational wind measurements throughout the Gulf of Maine, are used to explore the seasonal wind‐forced response of the gulf. Barotropic pressure fluctuations throughout the gulf are highly correlated all year (>0.75) and even more so in the winter (>0.85), with more than 90% of the variance explained by the relevant mode 1 empirical orthogonal functions (EOF). Both the pressures and the wind stress variability are concentrated in the 2‐ to 10‐day “weather band,” with typical winter wind stresses (0, 10 Pa) about 5 times more energetic than those in summer (0.05 Pa). Pressure fluctuations are highly correlated with 255°–75°T wind stress fluctuations. Typical gulf‐scale westward wind stress fluctuations force general gulf‐scale increases in the sea level pressure of about 10 eq cm in winter and about 4 eq cm in summer. The spatially averaged gulf pressure response to westward wind stress is 92±6 eq cm Pa −1 in winter and 83±8 eq cm Pa −1 in summer. The Gulf of Maine wind stress‐forced pressure variability was numerically modeled using the Dartmouth linear, homogeneous, three‐dimensional (3‐D), finite element diagnostic model (FUNDY 5). A series of 36‐hour‐averaged, spatially variable, optimally interpolated operational wind stress patterns was used to force model sea level pressure time series, which looked like observations and explained about 40% of the observed variance. The model provided detailed information on the linkage among the fluctuating near‐westward (eastward) wind stress‐forced surface Ekman transport into (out of) the gulf, the compensatory outflows (inflows) around Georges Bank, and the intensified flow along the western coast of the gulf.