Impact of GODAE products on nested HYCOM simulations of the West Florida Shelf
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Nested non-assimilative simulations of the West Florida Shelf for 2004–2005 are used to quantify the impact of initial and boundary conditions provided by Global Ocean Data Assimilation Experiment ocean products. Simulations are nested within an optimum interpolation hindcast of the Atlantic Ocean, the initial test of the US Navy Coupled Ocean Data Assimilation system for the Gulf of Mexico, and a global ocean hindcast that used the latter assimilation system. These simulations are compared to one that is nested in a non-assimilative Gulf of Mexico model to document the importance of assimilation in the outer model. Simulations are evaluated by comparing model results to moored Acoustic Doppler Current Profiler measurements and moored sea surface temperature time series. The choice of outer model has little influence on simulated velocity fluctuations over the inner and middle shelf where fluctuations are dominated by the deterministic wind-driven response. Improvement is documented in the representation of alongshore flow variability over the outer shelf, driven in part by the intrusion of the Loop Current and associated cyclones at the shelf edge near the Dry Tortugas. This improvement was realized in the simulation nested in the global ocean hindcast, the only outer model choice that contained a realistic representation of Loop Current transport associated with basin-scale wind-driven gyre circulation and the Atlantic Meridional Overturning Circulation. For temperature, the non-assimilative outer model had a cold bias in the upper ocean that was substantially corrected in the data-assimilative outer models, leading to improved temperature representation in the simulations nested in the assimilative outer models.
KeywordsNumerical modeling Coastal circulation
G. Halliwell was supported by the Office of Naval Research under award number N000140510892. Development and evaluation of the HYCOM nowcast/forecast system was supported by ONR under award number N000140410676. R. Weisberg was also supported by this grant along with ONR grant numbers N00014-05-1-0483 and N00014-02-1-0972, plus FFWCC/FMRI grant number S 7701 620071. We acknowledge the USF-CMS Ocean Circulation Group staff, R. Cole, J. Donovan, J. Law, C. Merz, R. Russell, and V. Subramanian, for the success of the WFS mooring program that provided the data used herein.
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