Chen, C.1, R. Houghton2, R. C. Beardsley3, Q.
Xu1, and H. Liu1
1School for Marine Science and Technology, University of
Massachusetts-Dartmouth, New Bedford, MA 025430
2Lamont Doherty Earth Observatory of Columbia University, Palisades,
NY 10964
3Department of Physical Oceanography, Woods Hole Oceanographic
Institution, Woods Hole, MA 02543.
Process-oriented experiments with the finite-volume coastal ocean
model FVCOM were conducted to examine the physical processes
controlling water movement on the southern flank of Georges Bank.
The experiments were focused on the mid-May/early June 1999 period
when fluorescent dye was released and tracked. Preliminary model
results show that the model dye movement is closely related to
vertical stratification. Once the dye mixes up in the entire water
column, it moves like a "Taylor column" that tends to follow the
near-surface Lagrangian current. Onset of vertical stratification
tends to slow down the upward diffusion of dye and traps the dye in
the mixed bottom boundary layer. In this case, the dye movement is
controlled mainly by the vertical shear of the Lagrangian current
throughout the dye-occupied water column. Horizontal resolution
plays an essential role in the spatial distribution and movement of
the dye. A 500-m horizontal resolution seems to be the minimum
requirement to resolve the spatia l size of the dye. A nudging
data-assimilation approach is being used to merge the model-computed
temperature and salinity with in-situ measurements made during the
dye field experiment. Direct comparison between model-predicted and
observed dye distribution and movement is also providing an
independent objective validation of FVCOM to study physical
processes on Georges Bank.
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