Surface forcing on the southern flank of Georges Bank, February–August 1995

Abstract

[1] Surface wind stress, heat, and freshwater fluxes were estimated over the southern flank of Georges Bank during February-August 1995 using moored measurements made at ST1 located on the 76-m isobath, roughly halfway between the tidal mixing and shelf/ slope fronts. Wind stress variability was dominated by a succession of atmospheric lows that passed Georges Bank during the deployment. A transition between frequent lows and strong wind stress events (''winter'') to less frequent lows and weaker wind stresses (''summer'') occurred in mid-May. In winter, wind stress fluctuations tended to be omnidirectional, with maximum stresses above 0.5 N/m 2 during four storms, one a classic ''nor'easter'', while summer fluctuations were weaker but strongly polarized in the alongbank direction. The ST1 surface heat flux was dominated by shortwave heating, which increased from a winter mean of 130 W/m 2 to 230 W/m 2 in summer. Long-wave cooling decreased from 50 W/m 2 (winter) to 30 W/m 2 (summer), while mean sensible and latent fluxes increased from À20 and À40 W/m 2 (winter) to +10 and 0 (summer) respectively. Overall, winter was characterized by weak net heating (30 W/m 2 ) with shortwave gain offset by long-wave, latent, and sensible heat loss. In summer, increased shortwave gain and reduced long-wave loss and weak sensible and latent fluxes combined to produce strong net heating (210 W/m 2 ). ST1 precipitation was highly episodic with little seasonality while evaporation occurred mostly during winter, resulting in a net evaporation of À15 cm and net freshwater flux of +48 cm over the deployment.

Cross-shelf circulation and momentum and heat balances over the inner continental shelf near Martha's Vineyard, Massachusetts

“…These results are consistent with previous studies of surface heat flux in the Middle Atlantic Bight (Bunker, 1976;Joyce, 1987;Austin and Lentz, 1999), over nearby Georges Bank (Beardsley et al, 2003), and in the Gulf of Maine (Mountain et al, 1996).…”

Heat and salt balances over the New England continental shelf, August 1996 to June 1997

“…This seasonal variation is qualitatively consistent with the seasonal variation in surface heat flux, i.e., surface warming in spring and summer and surface cooling in fall and winter [Beardsley and Boicourt, 1981;Joyce, 1987;Mountain et al, 1996;Beardsley et al, 2003]. However, the relative importance of advection to the seasonal variation in temperature, and to temperature variability in general, remains unclear because few observational studies have provided accurate estimates of the horizontal temperature gradients.…”

Temperature and salt balances on Georges Bank February–August 1995

“…No measurements were obtained between 47 and 61 m because of instrument failures. Meteorological measurements obtained at ST1 included wind speed and direction, air temperature, relative humidity, incoming short and longwave radiation, atmospheric pressure, and precipitation [ Beardsley et al , 2003].…”