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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, C02022, doi:10.1029/2003JC002195, 2005

Distant effect of assimilation of moored currents into a model of coastal wind-driven circulation off Oregon

Alexander L. Kurapov

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


J. S. Allen

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


G. D. Egbert

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


R. N. Miller

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


P. M. Kosro

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


M. Levine

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


T. Boyd

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


Abstract

An optimal interpolation (OI) sequential algorithm is implemented for a three-dimensional primitive equation model to assimilate current measurements from acoustic Doppler profilers moored on the Oregon shelf as a part of the Coastal Ocean Advances in Shelf Transport (COAST) upwelling experiment (May–August 2001). A stationary estimate of the forecast error covariance required by the OI is computed based on the error covariance in the model solution not constrained by data assimilation. Lagged model error covariances are used to account for the effect of previously assimilated data. The forecast error covariance has a shorter alongshore spatial scale than the model error covariance unconstrained by the data, as an effect of propagating dynamical modes. Assimilation of currents from one or two of the moorings located on the path of the upwelling jet helps to improve the model data rms error and correlation at the mooring sites located at an alongshore distance of 90 km, south or north from the assimilation sites. The coastal jet is deflected offshore over Heceta Bank, and assimilation of data from an inner-shelf mooring in the jet separation zone does not help to improve prediction in the far field. Larger improvements are obtained for the first part of the study period (yeardays 146–190). In the second part (days 191–237) the geometry of our limited area model possibly limits prediction accuracy. In numerical experiments involving assimilation of data from only one mooring the actual and expected rms error improvements are compared, providing a consistency test for the forecast error covariance.

Received 5 November 2003; accepted 17 September 2004; published 22 February 2005.

Keywords: coastal ocean prediction; data assimilation; upwelling.

Index Terms: 4217 Oceanography: General: Coastal processes; 4255 Oceanography: General: Numerical modeling (0545, 0560); 4260 Oceanography: General: Ocean data assimilation and reanalysis (3225); 4262 Oceanography: General: Ocean observing systems; 4263 Oceanography: General: Ocean predictability and prediction (3238).

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Citation: Kurapov, A. L., J. S. Allen, G. D. Egbert, R. N. Miller, P. M. Kosro, M. Levine, and T. Boyd (2005), Distant effect of assimilation of moored currents into a model of coastal wind-driven circulation off Oregon, J. Geophys. Res., 110, C02022, doi:10.1029/2003JC002195.