Surface wave effects on the translation of wind stress across the air–sea interface in a fetch-limited, coastal embayment

View/ Open
Date
2017-07-13Author
Fisher, Alexander W.
Concept link
Sanford, Lawrence P.
Concept link
Scully, Malcolm E.
Concept link
Suttles, Steven E.
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/9236As published
https://doi.org/10.1175/JPO-D-16-0146.1DOI
10.1175/JPO-D-16-0146.1Abstract
The role of surface gravity waves in structuring the air–sea momentum flux is examined in the middle reaches of Chesapeake Bay. Observed wave spectra showed that wave direction in Chesapeake Bay is strongly correlated with basin geometry. Waves preferentially developed in the direction of maximum fetch, suggesting that dominant wave frequencies may be commonly and persistently misaligned with local wind forcing. Direct observations from an ultrasonic anemometer and vertical array of ADVs show that the magnitude and direction of stress changed across the air–sea interface, suggesting that a stress divergence occurred at or near the water surface. Using a numerical wave model in combination with direct flux measurements, the air–sea momentum flux was partitioned between the surface wave field and the mean flow. Results indicate that the surface wave field can store or release a significant fraction of the total momentum flux depending on the direction of the wind. When wind blew across dominant fetch axes, the generation of short gravity waves stored as much as 40% of the total wind stress. Accounting for the storage of momentum in the surface wave field closed the air–sea momentum budget. Agreement between the direction of Lagrangian shear and the direction of the stress vector in the mixed surface layer suggests that the observed directional difference was due to the combined effect of breaking waves producing downward sweeps of momentum in the direction of wave propagation and the straining of that vorticity field in a manner similar to Langmuir turbulence.
Description
Author Posting. © American Meteorological Society, 2017. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 47 (2017): 1921-1939, doi:10.1175/JPO-D-16-0146.1.
Collections
Suggested Citation
Journal of Physical Oceanography 47 (2017): 1921-1939Related items
Showing items related by title, author, creator and subject.
-
Western Maine Coastal Current reduces primary production rates, zooplankton abundance and benthic nutrient fluxes in Massachusetts Bay
McManus, M. Conor; Oviatt, Candace A.; Giblin, Anne E.; Tucker, Jane; Turner, Jefferson T. (2013-08)Primary production was measured from 1992-2010 in Massachusetts Bay and just outside Boston Harbor for the Massachusetts Water Resources Authority’s outfall monitoring program. In 2003, annual primary production decreased ... -
Downfront winds over buoyant coastal plumes
Spall, Michael A.; Thomas, Leif N. (American Meteorological Society, 2016-10-07)Downfront, or downwelling favorable, winds are commonly found over buoyant coastal plumes. It is known that these winds can result in mixing of the plume with the ambient water and that the winds influence the transport, ... -
Fluid mechanical measurements within the bottom boundary layer during coastal mixing and optics
Fredericks, Janet J.; Trowbridge, John H.; Williams, Albert J.; Voulgaris, George; Shaw, William J. (Woods Hole Oceanographic Institution, 2001-08)To quantify and understand the role of vertical mixing processes in determining mid-shelf vertical structure of hydrographic and optical properties and particulate matter, the Office of Naval Research (ONR) funded a program ...