Long-term moored array measurements of currents and hydrography over Georges Bank: 1994–1999

Abstract

Abstract:In conjunction with the GLOBEC (Global Ocean Ecosystems Dynamics) program, measurements of moored currents, temperature and salinity were made during 1994-1999 at locations in 76 m of water along the Southern Flank of Georges Bank and at the Northeastern Peak. The measurements concentrate on the biologically crucial winter and spring periods, and coverage during the fall is usually poorer.Current time series were completely dominated by the semidiurnal M 2 tidal component, while other tidal species (including the diurnal K 1 component) were also important. There was a substantial wind-driven component of the flow, which was linked, especially during the summer, to regional-scale response patterns. The current response at the Northeast Peak was especially strong in the 3-4 day period band, and this response is shown to be related to an amplifying topographic wave propagating eastward along the northern flank. Monthly mean flows on the southern flank are southwestward throughout the year, but strongest in the summertime. The observed tendency for summertime maximum along-bank flow to occur at depth is rationalized in terms of density gradients associated with a near-surface freshwater tongue wrapping around the Bank.Temperature and salinity time series demonstrate the presence, altogether about 25% of the time, of a number of intruding water masses. These intrusions could last anywhere from a couple days up to about a month. The sources of these intrusions can be broadly classified as the Scotian Shelf (especially during the winter), the Western Gulf of Maine (especially during the summer), and the deeper ocean south of Georges Bank (throughout the year). On longer time scales, the temperature variability is dominated by seasonal temperature changes. During the spring and summer, these changes are balanced by local heating or cooling, but wintertime cooling involves advective lateral transports as well. Salinity variations have weak, if any, seasonal variability, but are dominated by interannual changes that are related to regional-or basin-scale changes.All considered, Georges Bank temperature and salinity characteristics are found to be highly dependent on the surrounding waters, but many questions remain, especially in terms of whether intrusive events leave a sustained impact on Bank waters.Regional Index Terms: Northeast US shelf; Gulf of Maine; Georges Bank

Diagnosing the warming of the Northeastern U.S. Coastal Ocean in 2012: A linkage between the atmospheric jet stream variability and ocean response

“…T−T 0 and Q cum are then examined to characterize the relative importance of atmospheric forcing and ocean advection to the depth‐averaged temperature budget at the three buoys in the MAB. During November 2011 to June 2012, the temperature budget of shelf water near either Nantucket (buoy 44008) or Long Island (buoy 44025) is largely balanced between the atmospheric heat flux and the local rate of change (Figure ), consistent with previous studies at the southern flank of Georges Bank [ Brink et al ., ]. However, at Virginia Beach (buoy 44099), the relationship between T−T 0 and Q cum is relatively weak.…”

Seasonal warming of the Middle A tlantic B ight C old P ool

“…The time series include: the 1955–1972 archive of daily temperature profiles collected at nine lightships in relatively shallow water (∼30 m; except Nantucket Lightship 60 m) [ Shearman and Lentz , ]; George Bank [ Butman et al . ; Brink et al ., ]; the New England shelf [ Beardsley et al ., ; Aikman et al ., ; Shearman and Lentz , ], the New York Bight [ Mayer , ], and the southern MAB [ Berger et al ., ; Biscaye et al ., ; Pietrafesa et al ., ]. The time series are at least 200 days long, and in some cases span several years.…”

Observations of storm‐induced mixing and Gulf Stream Ring incursion over the southern flank of Georges Bank: Winter and summer 1997

“…This is especially true in regions such as the southern flank of Georges Bank, where energetic short time‐scale and space‐scale variability dominates the observations. SeaSoar surveys do not provide sufficient temporal resolution to permit reliable estimation of the decorrelation time scales, although velocity measurements from the South Flank mooring [e.g., Brink et al , 2009] suggest e‐folding times of 1–3 days for detided time series. Temporal scales for temperature and salinity appear to be longer.…”