Wave-Driven Inner-Shelf Motions on the Oregon Coast*

Journal of Physical Oceanography - Tập 39 Số 11 - Trang 2942-2956 - 2009
Anthony Kirincich1, Steven J. Lentz1, John A. Barth2
1Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
2College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

Tóm tắt

Abstract Recent work by S. Lentz et al. documents offshore transport in the inner shelf due to a wave-driven return flow associated with the Hasselmann wave stress (the Stokes–Coriolis force). This analysis is extended using observations from the central Oregon coast to identify the wave-driven return flow present and quantify the potential bias of wind-driven across-shelf exchange by unresolved wave-driven circulation. Using acoustic Doppler current profiler (ADCP) measurements at six stations, each in water depths of 13–15 m, observed depth-averaged, across-shelf velocities were generally correlated with theoretical estimates of the proposed return flow. During times of minimal wind forcing, across-shelf velocity profiles were vertically sheared, with stronger velocities near the top of the measured portion of the water column, and increased in magnitude with increasing significant wave height, consistent with circulation due to the Hasselmann wave stress. Yet velocity magnitudes and vertical shears were stronger than that predicted by linear wave theory, and more similar to the stratified “summer” velocity profiles described by S. Lentz et al. Additionally, substantial temporal and spatial variability of the wave-driven return flow was found, potentially due to changing wind and wave conditions as well as local bathymetric variability. Despite the wave-driven circulation found, subtracting estimates of the return flow from the observed across-shelf velocity had no significant effect on estimates of the across-shelf exchange due to along-shelf wind forcing at these water depths along the Oregon coast during summer.

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Tài liệu tham khảo

Austin, 2002, The inner shelf response to wind-driven upwelling and downwelling., J. Phys. Oceanogr., 32, 2171, 10.1175/1520-0485(2002)032<2171:TISRTW>2.0.CO;2

Barth, 2007, Delayed upwelling alters nearshore coastal ocean ecosystems in the northern California Current., Proc. Natl. Acad. Sci. USA, 104, 3719, 10.1073/pnas.0700462104

Chelton, 1983, Effects of sampling errors in statistical estimation., Deep-Sea Res., 30, 1083, 10.1016/0198-0149(83)90062-6

Fewings, 2008, Observations of cross-shore flow driven by cross-shelf winds on the inner continental shelf., J. Phys. Oceanogr., 38, 2358, 10.1175/2008JPO3990.1

Garrett, 1981, Dynamical aspects of the flow through the strait of Belle Isle., J. Phys. Oceanogr., 11, 376, 10.1175/1520-0485(1981)011<0376:DAOTFT>2.0.CO;2

Hasselmann, 1970, Wave-driven inertial oscillations., Geophys. Astrophys. Fluid Dyn., 1, 463, 10.1080/03091927009365783

Huyer, 1983, Coastal upwelling in the California Current System., Prog. Oceanogr., 12, 259, 10.1016/0079-6611(83)90010-1

Kirincich, 2009, Time-varying across-shelf Ekman transport and vertical eddy viscosity on the inner-shelf., J. Phys. Oceanogr., 39, 602, 10.1175/2008JPO3969.1

Kirincich, 2005, Wind-driven inner-shelf circulation off central Oregon during summer., J. Geophys. Res., 110, C10S03, 10.1029/2004JC002611

Large, 1981, Open ocean momentum flux measurements in moderate to strong winds., J. Phys. Oceanogr., 11, 324, 10.1175/1520-0485(1981)011<0324:OOMFMI>2.0.CO;2

Lentz, 2001, A dynamical description of fall and winter mean current profiles over the northern California shelf., J. Phys. Oceanogr., 31, 914, 10.1175/1520-0485(2001)031<0914:ADDOFA>2.0.CO;2

Lentz, 2008, Observations and a model of undertow over the inner continental shelf., J. Phys. Oceanogr., 38, 2341, 10.1175/2008JPO3986.1

Madsen, 1978, Mass transport in deep-water waves., J. Phys. Oceanogr., 8, 1009, 10.1175/1520-0485(1978)008<1009:MTIDWW>2.0.CO;2

Monismith, 2004, A note on the potential transport of scalars and organisms by surface waves., Limnol. Oceanogr., 49, 1214, 10.4319/lo.2004.49.4.1214

Mooers, 1968, A compilation of observations from moored current meters and thermographs (and of complementary oceanographic and atmospheric data).

Newberger, 2007, Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone: 2. Application to DUCK94., J. Geophys. Res., 112, C08019

Perrie, 2003, The impact of waves on surface currents., J. Phys. Oceanogr., 33, 2126, 10.1175/1520-0485(2003)033<2126:TIOWOS>2.0.CO;2

Polton, 2005, The role of wave-induced Coriolis–Stokes forcing on the wind-driven mixed layer., J. Phys. Oceanogr., 35, 444, 10.1175/JPO2701.1

Rascle, 2006, Drift and mixing under the ocean surface: A coherent one-dimensional description with application to unstratified conditions., J. Geophys. Res., 111, C03016, 10.1029/2005JC003004

Reed, 1992, Linear least-squares fits with errors in both coordinates., Amer. J. Phys., 60, 59, 10.1119/1.17044

Samelson, 2002, Wind stress forcing of the Oregon coastal ocean during the 1999 upwelling season., J. Geophys. Res., 107, 3034, 10.1029/2001JC000900

Tilburg, 2003, Across-shelf transport on a continental shelf: do across-shelf winds matter?, J. Phys. Oceanogr., 33, 2675, 10.1175/1520-0485(2003)033<2675:ATOACS>2.0.CO;2

Ursell, 1950, On the theoretical form of ocean swell on a rotating earth., Mon. Not. Roy. Astron. Soc. Geophys., 6, 1, 10.1111/j.1365-246X.1950.tb02968.x

Weber, 1981, Ekman currents and mixing due to surface gravity waves., J. Phys. Oceanogr., 11, 1431, 10.1175/1520-0485(1981)011<1431:ECAMDT>2.0.CO;2

Weber, 1983, Steady wind- and wave-induced currents in the open ocean., J. Phys. Oceanogr., 13, 524, 10.1175/1520-0485(1983)013<0524:SWAWIC>2.0.CO;2

Weber, 2003, Wave-induced mass transport in the oceanic surface layer., J. Phys. Oceanogr., 33, 2527, 10.1175/1520-0485(2003)033<2527:WMTITO>2.0.CO;2

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Thông tin xuất bản

Journal of Physical Oceanography

Tập 39 Số 11

2942-2956

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