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Realistic atmospheric, runoff, throughflow, and tidal forcing (in some cases) functions are used to drive a numerical simulation, using the Princeton Ocean Model (POM), of the seasonal cycle for Prince William Sound (PWS), Alaska circulation during 1996. Physical observations from the Sound Ecosystem Assessment (SEA) Program are used to provide initial conditions and open (lateral) boundary conditions, and, above all, for model validation. This study is the first comprehensive model validation effort for PWS using realistic model attributes and a variety of observations. Considering the uncertainties in the forcing functions, the seasonal cycles of upper ocean heating and salinification exhibit substantial agreement between simulations and observations. The flow fields exhibit characteristic patterns associated with both seasonal variations and wind transients (“weather cycle”). Contrasting results of two extreme cases, one with daily velocity profiles given at the Hinchinbrook Entrance (HE) open boundary and the other with only the monthly transport given there, clearly demonstrates the importance of detailed temporal/spatial flow structures at the HE open boundary on the estimation of circulation and stratification in PWS. For example, hourly wind forcing alone is not capable of reproducing synoptic variations in the observed temperature and velocity, indicative of the importance of horizontal advection from outside PWS. However, discrepancies in thermohaline and velocity structure indicate the need for future refinements, especially in the forcing functions and domain selection prior to detailed diagnostic studies. For example, the interactions between PWS and the adjacent continental shelf were prescribed at open boundaries from incomplete information, and, thus, did not admit the full range of dynamical interchange between PWS and the shelf. Furthermore, substantially more time-depth observations of the flow and mass fields are needed for validating the present generation of comprehensive numerical circulation models for PWS so they can be more widely used in applications. |
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