Publication Date:
2022-05-25
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2007.
Description:
The water circulation and evolution of water temperature over the inner continental
shelf are investigated using observations of water velocity, temperature, density, and
bottom pressure; surface gravity waves; wind stress; and heat flux between the ocean
and atmosphere during 2001-2007.
When waves are small, cross-shelf wind stress is the dominant mechanism driving
cross-shelf circulation. The along-shelf wind stress does not drive a substantial cross-shelf
circulation. The response to a given wind stress is stronger in summer than
winter. The cross-shelf transport in the surface layer during winter agrees with a
two-dimensional, unstratified model. During large waves and onshore winds the cross-shelf
velocity is nearly vertically uniform, because the wind- and wave-driven shears
cancel. During large waves and offshore winds the velocity is strongly vertically
sheared because the wind- and wave-driven shears have the same sign.
The subtidal, depth-average cross-shelf momentum balance is a combination of
geostrophic balance and a coastal set-up and set-down balance driven by the cross-shelf
wind stress. The estimated wave radiation stress gradient is also large. The
dominant along-shelf momentum balance is between the wind stress and pressure
gradient, but the bottom stress, acceleration, Coriolis, Hasselmann wave stress, and
nonlinear advection are not negligible. The
fluctuating along-shelf pressure gradient is
a local sea level response to wind forcing, not a remotely generated pressure gradient.
In summer, the water is persistently cooled due to a mean upwelling circulation.
The cross-shelf heat
flux nearly balances the strong surface heating throughout midsummer,
so the water temperature is almost constant. The along-shelf heat
flux
divergence is apparently small. In winter, the change in water temperature is closer
to that expected due to the surface cooling. Heat transport due to surface gravity
waves is substantial.
Description:
My last three years of thesis work were supported by National Aeronautics and
Space Administration Headquarters under the Earth System Science Fellowship Grant
NNG04GQ14H, and by WHOI Academic Programs Fellowship Funds. I also benefited
from the freedom of a Clare Boothe Luce Fellowship during my first year in the Joint
Program, which allowed me more time than is usual to explore different research
topics before choosing an advisor.
This research was also funded by the National Aeronautics and Space Administration
under grant NNG04GL03G and the Ocean Sciences Division of the National
Science Foundation under grants OCE-0241292 and OCE-0548961. The Martha's
Vineyard Coastal Observatory is partly funded by the Woods Hole Oceanographic
Institution and the Jewett/EDUC/Harrison Foundation. The ADCP deployments at
CBLAST site F were funded by National Science Foundation Small Grant for Exploratory
Research OCE-0337892. Ship time for deployment and recovery of the F
ADCP was provided by Robert Weller through Office of Naval Research contracts
N00014-01-1-0029 and N00014-05-10090 for the Low-Wind Component of the Coupled
Boundary Layers Air-Sea Transfer Experiment.
Keywords:
Ocean circulation
;
Ocean-atmosphere interaction
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
application/pdf
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