Analysis of observed and modeled mixed layers: NOCAL region
Durban, Diane C.
Mooers, Christopher N.K.
Garwood, Roland W., Jr.
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Surface mixed properties off Northern California (NOCAL) were analyzed statistically and numerically. The observations were acquired on three cruises as part of the Pilot Ocean Prediction Study of the California Current eddies centered ca. 37 to 39N, 125 to 127W during March and August 1982. Mixed layer depth, averaging 33+/-14 m, had a horizontal correlation scale of no more than 35 km, which has significance for relating thermal structure information from individual temperature profiles to that of Fleet Numerical Oceanography Center's (FNOC) analyses based on a grid length of approximately 300km. Simulations and sensitivity tests were made using the Garwood bulk mixed layer model and the Mellor Level-2.5 diffusion model with the initial and boundary conditions acquired at sea and from FNOC. Upper ocean thermal structure analyses and forecasts were also obtained from the Navy's TOPS/TOPS-EOTS diffusion model, which has since become operational at FNOC. Comparisons of observations, analyses, and model solutions reveal consistent cooling and deepening by the two former models and excessive warming by the latter model. These significant differences are believed to be related to model resolution, model sensitivity, oceanic and atmospheric data quality, and spatial variability.
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