Ps. Bogden et al., OPEN-OCEAN BOUNDARY-CONDITIONS FROM INTERIOR DATA - LOCAL AND REMOTE FORCING OF MASSACHUSETTS-BAY, J GEO RES-O, 101(C3), 1996, pp. 6487-6500
Massachusetts and Cape Cod Bays form a semienclosed coastal basin that
opens onto the much larger Gulf of Maine, Subtidal circulation in the
bay is driven by local winds and remotely driven flows from the gulf.
The local-wind forced flow is estimated with a regional shallow water
model driven by wind measurements, The model uses a gravity wave radi
ation condition along the open-ocean boundary. Results compare reasona
bly well with observed currents near the coast. In some offshore regio
ns however, modeled flows are an order of magnitude less energetic tha
n the data. Strong flows are observed even during periods of weak loca
l wind forcing. Poor model-data comparisons are attributable, at least
in part, to open-ocean boundary conditions that neglect the effects o
f remote forcing. Velocity measurements from within Massachusetts Bay
are used to estimate the remotely forced component of the flow, The da
ta are combined with shallow water dynamics in an inverse-model formul
ation that follows the theory of Bennett and McIntosh [1982], who cons
idered tides. We extend their analysis to consider the subtidal respon
se to transient forcing. The inverse model adjusts the a priori open-o
cean boundary condition, thereby minimizing a combined measure of mode
l-data misfit and boundary condition adjustment. A ''consistency crite
rion'' determines the optimal trade-off between the two. The criterion
is based on a measure of plausibility for the inverse solution. The '
'consistent'' inverse solution reproduces 56% of the average squared v
ariation in the data, The local-wind-driven flow alone accounts for ha
lf of the model skill. The other half is attributable to remotely forc
ed flows from the Gulf of Maine. The unexplained 44% comes from measur
ement errors and model errors that are not accounted for in the analys
is.