Quasi-operational coastal ocean nowcast/forecast systems

摘要

For several years, quasi-operational (i.e., real-time, semi-autonomous, research-mode) nowcast/forecast systems have been run in two quite different regimes: (1) the Straits of Florida/East Florida Shelf, which includes the Florida Current, and (2) Prince William Sound, Alaska, which is a small, semi-enclosed sea with two major straits. For both regimes, the Princeton Ocean Model (POM) has been implemented with mesoscale resolution. Both implementations are forced by mesoscale numerical weather predictions, the US Navy's operational global ocean model (NCOM, which assimilates satellite altimetric sea surface height anomalies, MCSST, ARGO float temperature and salinity profiles, etc.) for open boundary conditions, and four diurnal and four semi-diurnal tides, also imposed on the open boundaries. Real-time observations are mainly used for model skill assessment, as a prelude to data assimilation. One of the benefits of this activity has been new understanding derived from diagnostics studies made possible by these numerical simulations. For example, the Florida Current Frontal (cyclonic) Eddies, which form weekly in the cyclonic shear zone along the shelfbreak, have been more fully characterized than had been possible by observations alone, and the prevalence of three-layered monthly mean flow in the straits of Prince William Sound has been determined in a highly variable regime that is difficult to observe comprehensively.