Upcoming North Sea Study (LIFECO) (St. John)
Scotian Shelf Cross-over
Satellite Observations of the Front
University of Massachusetts - Dartmouth
1) Literature/historical data show that satellite-derived
Sea Surface Temperature
(SST) images may be used to delineate regions within the Gulf of Maine (GOM) & Georges Bank (GB) where
strong tidal mixing occurs.
2) Annual signals dominate the
variance for both SST and SST fronts.
Construct time series of both
satellite-derived SST and the locations of highest SST gradient (fronts) using
- Use empirical orthogonal functions (EOF) to
examine the signal variance.
- This mixing must have important physical, chemical, and
biological implications for GB.
Areas of high and low annual SST
signal amplitude correspond to seasonally-stratified and
well-mixed regions on GB, respectively, which are separated by narrow regions
of high SST frontal probability, signifying seasonal Tidal Mixing Fronts (TMFs).
monthly mean, SST frontal probability density function (PDF) maps show that a primary TMF forms on the
southern flank of GB during May of each year and moves bankward (into more
shallow waters) ~5-km per month during the heating season from June-August. The
TMF on the northern flank of GB moves into deeper waters at a somewhat lesser
rate over the same period.
- A secondary TMF forms bankward of the primary
TMF by late summer, separating cooler water at the primary TMF from the warm
thermostable hot-spot on the crest of GB.
- Both the primary and secondary
TMFs disappear by late fall of each year when the entire GB region becomes
well-mixed due to rapid cooling and wind mixing.
- Both primary and secondary TMFs, along with the shelf/slope front, and SSW
cross-overs are captured in an EOF analysis of SST frontal PDF maps.
single isobath, nor Simpson-Hunter depth-dissipation value, log10(h/Dt), may
be used to locate the TMF during months when TMFs are present.
J. J., K. W. Seemann and T. P. Mavor, High-resolution
sea surface temperature variability over the Gulf of
Maine and Georges
Bank region, 1993-1996. Deep-Sea Research II (in press).
P. and J. J. Bisagni, Seasonal variability of sea surface
on Georges Bank. Deep-Sea Research II (in press).