Mapping the U.S. West Coast surface circulation: A multiyear analysis of high-frequency radar observations

  1. Sung Yong Kim1,
  2. Eric J. Terrill1,
  3. Bruce D. Cornuelle1,
  4. Burt Jones2,
  5. Libe Washburn3,
  6. Mark A. Moline4,
  7. Jeffrey D. Paduan5,
  8. Newell Garfield6,
  9. John L. Largier7,
  10. Greg Crawford8,10,
  11. P. Michael Kosro9

Article first published online: 5 MAR 2011

DOI: 10.1029/2010JC006669

Issue

Journal of Geophysical Research: Oceans (1978–2012)

Journal of Geophysical Research: Oceans (1978–2012)

Additional Information

How to Cite

Kim, S. Y., et al. (2011), Mapping the U.S. West Coast surface circulation: A multiyear analysis of high-frequency radar observations, J. Geophys. Res., 116, C03011, doi:10.1029/2010JC006669.

Author Information

  1. 1

    Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA

  2. 2

    Department of Biological Sciences, University of Southern California, Los Angeles, California, USA

  3. 3

    Institute for Computational Earth System Science, Department of Geography, University of California, Santa Barbara, California, USA

  4. 4

    Biological Sciences Department, California Polytechnic State University, San Luis Obispo, California, USA

  5. 5

    Department of Oceanography, Graduate School of Engineering and Applied Sciences, Naval Postgraduate School, Monterey, California, USA

  6. 6

    Geosciences Department and Romberg Tiburon Center for Environmental Studies, San Francisco State University, Tiburon, California, USA

  7. 7

    Bodega Marine Laboratory, University of California, Davis, Bodega Bay, California, USA

  8. 8

    Department of Oceanography, Humboldt State University, Arcata, California, USA

  9. 9

    College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA

  10. 10

    Now at the Faculty of Science and Technology, Vancouver Island University, Nanaimo, British Columbia, Canada.

Publication History

  1. Issue published online: 5 MAR 2011
  2. Article first published online: 5 MAR 2011
  3. Manuscript Accepted: 8 DEC 2010
  4. Manuscript Revised: 22 NOV 2010
  5. Manuscript Received: 21 SEP 2010

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Keywords:

  • surface currents;
  • high-frequency radar;
  • submesoscale;
  • wave number spectra

[1] The nearly completed U.S. West Coast (USWC) high-frequency radar (HFR) network provides an unprecedented capability to monitor and understand coastal ocean dynamics and phenomenology through hourly surface current measurements at up to 1 km resolution. The dynamics of the surface currents off the USWC are governed by tides, winds, Coriolis force, low-frequency pressure gradients (less than 0.4 cycles per day (cpd)), and nonlinear interactions of those forces. Alongshore surface currents show poleward propagating signals with phase speeds of O(10) and O(100 to 300) km day−1 and time scales of 2 to 3 weeks. The signals with slow phase speed are only observed in southern California. It is hypothesized that they are scattered and reflected by shoreline curvature and bathymetry change and do not penetrate north of Point Conception. The seasonal transition of alongshore surface circulation forced by upwelling-favorable winds and their relaxation is captured in fine detail. Submesoscale eddies, identified using flow geometry, have Rossby numbers of 0.1 to 3, diameters in the range of 10 to 60 km, and persistence for 2 to 12 days. The HFR surface currents resolve coastal surface ocean variability continuously across scales from submesoscale to mesoscale (O(1) km to O(1000) km). Their spectra decay with k−2 at high wave number (less than 100 km) in agreement with theoretical submesoscale spectra below the observational limits of present-day satellite altimeters.

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