Variability in the properties of Shelf Water in the Middle Atlantic Bight, 1977–1999

Abstract

[1] The seasonal and interannual variability in the temperature, salinity, and volume of Shelf Water (SHW) in the Middle Atlantic Bight (MAB) is described for the period 1977-1999. Large interannual variations in the volume, salinity, and, to a lesser extent, temperature of the SHW occurred that were coherent over multiple year time periods. The variations in volume and salinity originated through processes acting outside of the MAB and were advected into the region from the Gulf of Maine. On a decadal average the SHW observed in the 1990s was approximately 1°C warmer, 0.25 PSU fresher, and 1000 km 3 more abundant than during the 1977-1987 period. The warming during the 1990s was largest in the southern part of the bight during the winter, when the SHW was more than 2°C warmer then during the earlier decade.

A Numerical Model Analysis of the Mean and Seasonal Nitrogen Budget on the Northeast U.S. Shelf

“…The simulated annual mean velocity field on the NEUS shelf averaged from surface to 50‐m depth is presented in Figure . Consistent with the schematic circulation pattern in Figure and previous observational and modeling studies (e.g., Beardsley et al, ; Mountain, ; Zhang et al, ), the NEUS shelf circulation includes an inflow from the Scotian Shelf to the GoM intensifying along the coast, an anticyclonic circulation on GB with strong currents over 15 cm/s, and a southwestward along‐shelf flow averaging 5 cm/s over the MAB. A branch of the shelf break current enters the GoM through the Northeast Channel, and another branch directly merges with the anticyclonic gyre along the southern flank of GB, creating a narrow and intensified jet westward to the Hudson Shelf Valley.…”

A Numerical Model Analysis of the Mean and Seasonal Nitrogen Budget on the Northeast U.S. Shelf

“…The simulated annual mean velocity field on the NEUS shelf averaged from surface to 50‐m depth is presented in Figure . Consistent with the schematic circulation pattern in Figure and previous observational and modeling studies (e.g., Beardsley et al, ; Mountain, ; Zhang et al, ), the NEUS shelf circulation includes an inflow from the Scotian Shelf to the GoM intensifying along the coast, an anticyclonic circulation on GB with strong currents over 15 cm/s, and a southwestward along‐shelf flow averaging 5 cm/s over the MAB. A branch of the shelf break current enters the GoM through the Northeast Channel, and another branch directly merges with the anticyclonic gyre along the southern flank of GB, creating a narrow and intensified jet westward to the Hudson Shelf Valley.…”

Contrasting Response of the Eastern and Western North Atlantic Circulation to an Episodic Climate Event*

“…Model-derived salinity time series (Fig. 2) show reasonable agreement with hydrographic observations reported by Mountain (2003) for the New York Bight region. The sustained pulse of low-saline water thus progresses southward and onto shallower regions.…”

Cross‐shelf transport of freshwater on the New Jersey shelf

“…The rapid cross‐shelf transport of the Hudson River outflow is consistent with analysis by Mountain [2003] who noted a significant annual cycle in the shelf salinity in the New York Bight Apex, and that this seasonal variability was absent to the south off Delaware and Chesapeake Bays. Mountain's results were based on coarse CTD surveys that we suggest may have missed the seasonal freshwater signal discharging from the Delaware and Chesapeake Bays that may have been largely contained in a narrow coastal current.…”

A Numerical Model Analysis of the Mean and Seasonal Nitrogen Budget on the Northeast U.S. Shelf

“…The simulated annual mean velocity field on the NEUS shelf averaged from surface to 50‐m depth is presented in Figure . Consistent with the schematic circulation pattern in Figure and previous observational and modeling studies (e.g., Beardsley et al, ; Mountain, ; Zhang et al, ), the NEUS shelf circulation includes an inflow from the Scotian Shelf to the GoM intensifying along the coast, an anticyclonic circulation on GB with strong currents over 15 cm/s, and a southwestward along‐shelf flow averaging 5 cm/s over the MAB. A branch of the shelf break current enters the GoM through the Northeast Channel, and another branch directly merges with the anticyclonic gyre along the southern flank of GB, creating a narrow and intensified jet westward to the Hudson Shelf Valley.…”

Contrasting Response of the Eastern and Western North Atlantic Circulation to an Episodic Climate Event*

“…Model-derived salinity time series (Fig. 2) show reasonable agreement with hydrographic observations reported by Mountain (2003) for the New York Bight region. The sustained pulse of low-saline water thus progresses southward and onto shallower regions.…”

Cross‐shelf transport of freshwater on the New Jersey shelf

“…The rapid cross‐shelf transport of the Hudson River outflow is consistent with analysis by Mountain [2003] who noted a significant annual cycle in the shelf salinity in the New York Bight Apex, and that this seasonal variability was absent to the south off Delaware and Chesapeake Bays. Mountain's results were based on coarse CTD surveys that we suggest may have missed the seasonal freshwater signal discharging from the Delaware and Chesapeake Bays that may have been largely contained in a narrow coastal current.…”

A Numerical Model Analysis of the Mean and Seasonal Nitrogen Budget on the Northeast U.S. Shelf

“…The simulated annual mean velocity field on the NEUS shelf averaged from surface to 50‐m depth is presented in Figure . Consistent with the schematic circulation pattern in Figure and previous observational and modeling studies (e.g., Beardsley et al, ; Mountain, ; Zhang et al, ), the NEUS shelf circulation includes an inflow from the Scotian Shelf to the GoM intensifying along the coast, an anticyclonic circulation on GB with strong currents over 15 cm/s, and a southwestward along‐shelf flow averaging 5 cm/s over the MAB. A branch of the shelf break current enters the GoM through the Northeast Channel, and another branch directly merges with the anticyclonic gyre along the southern flank of GB, creating a narrow and intensified jet westward to the Hudson Shelf Valley.…”

Contrasting Response of the Eastern and Western North Atlantic Circulation to an Episodic Climate Event*

“…Model-derived salinity time series (Fig. 2) show reasonable agreement with hydrographic observations reported by Mountain (2003) for the New York Bight region. The sustained pulse of low-saline water thus progresses southward and onto shallower regions.…”

Cross‐shelf transport of freshwater on the New Jersey shelf

“…The rapid cross‐shelf transport of the Hudson River outflow is consistent with analysis by Mountain [2003] who noted a significant annual cycle in the shelf salinity in the New York Bight Apex, and that this seasonal variability was absent to the south off Delaware and Chesapeake Bays. Mountain's results were based on coarse CTD surveys that we suggest may have missed the seasonal freshwater signal discharging from the Delaware and Chesapeake Bays that may have been largely contained in a narrow coastal current.…”