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Ocean-atmosphere high resolution modeling of the Adriatic Sea during winter and spring 2001
Julie Pullen, NRL, Monterey, CA; and J. D. Doyle, R. Hodur, A. Ogston, J. Book, H. Perkins, and R. Signell
Realistic simulations of the Adriatic Sea are presented using the Navy Coastal Ocean Model (NCOM), with atmospheric forcing provided by the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPSTM). The modeling system consists of a 6-km resolution NCOM model of the entire Mediterranean Sea, with forcing from a 27-km resolution COAMPS reanalysis, and an embedded 2-km NCOM model of the Adriatic Sea. In two separate simulations, the 2-km Adriatic Sea ocean model is forced by the inner (4-km) and outer (36-km) nests of a triply nested COAMPS reanalysis centered on the Adriatic. In addition, the 2-km Adriatic Sea model is forced by observed daily river discharge values from the Po River. We evaluate ocean and atmosphere modeled wind and current fields using observations from 28 January – 4 June 2001 (125 days).
The Adriatic COAMPS reanalyses are compared with observed wind velocity at two land-based sites in the northern Adriatic. Mean winds are within 0.88 m/s of the observed values and correlations with observations exceed 0.85 for both resolution simulations. The 4 km reanalysis is differentiated from the 36 km reanalysis by its ability to resolve the small-scale wind flow structures associated with the bora and by its ability to better match the observed standard deviations.
Validation of the Adriatic Sea ocean model is performed using 2 ADCP measurements deployed 125 km apart. For both forcing resolutions, modeled 5-m velocity fluctuations generally match the magnitude and orientation of the observed standard deviation at both sites. In addition, the modeled structure of the current with depth at the deeper site reproduces the observed barotropic nature of the mean and standard deviation. Using EOF analysis, the ocean simulation forced by the 4-km resolution model is distinguished from the one forced by the 36-km resolution model by the formers ability to reproduce the expected double gyre circulation in the northern Adriatic and by its higher correlation with observations (greater than 0.78) at subsurface depths where the circulation is shown to be strongly wind-driven.
Session 1, Air-Sea Processes and Modeling
Wednesday, 6 August 2003, 10:30 AM-3:30 PM
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