Abstract
Analysis of forty years of tide gauge data and reanalysis wind stresses
from the Middle Atlantic Bight indicate that along-shelf wind stresses
are a dominant driver of coastal dynamic sea level (sea level plus
atmospheric pressure) variability at daily to yearly time scales. The
sea-level response to along-shelf wind stress varies substantially along
the coast and is accurately reproduced by a steady, barotropic,
depth-averaged model (Csanady 1978, Arrested Topographic Wave). The
model indicates that the sea-level response in the MAB depends primarily
on the along-shelf distribution of the along-shelf wind stress, the
Coriolis frequency, the bottom drag coefficient, and the cross-shelf
bottom slope. The along-shelf wind stress varies along the MAB shelf due
primarily to changes in the shelf orientation. The sea-level response
depends on both the local and upstream (in the sense of Kelvin wave
propagation) along-shelf wind stresses. Consequently, sea-level
variability at daily, monthly and yearly time scales along much of the
central MAB coast is more strongly driven by upstream winds along the
southern New England shelf than by local winds along the central MAB
shelf. The residual coastal sea-level variability, after removing the
wind-driven response and the trend, is roughly uniform along the MAB
coast. The along-coast average of the residual sea level at monthly and
yearly time scales is caused by variations in shelf water densities
primarily associated with the large annual cycle in water temperature
and interannual variations in salinity.