The GoMOOS nowcast/forecast system

A circulation nowcast/forecast system has been developed for the Gulf of Maine as an integral component of the Gulf of Maine Ocean Observing System (GoMOOS). It has been used daily since 2001 to produce short-term forecasts of the circulation and hydrographic properties in the Gulf of Maine. One of the expectations is that the nowcast/forecast system can provide consistent SST to fill in AVHRR data gaps and eventually produce reliable 3D temperature and flow fields for fisheries and other applications.The framework of the nowcast/forecast system is presented, including an algorithm for assimilating satellite-derived SST. Comparisons between the predicted and the observed temperature (both in situ and satellite-derived) and velocity are discussed. In general, the assimilation algorithm is stable and produces robust SST patterns. Seasonal variations in temperature and the coastal current are reasonably reproduced. Correlation between the modeled and observed fields in the synoptic band is summarized for individual buoys in monthly bins. The Root-Mean-Square (RMS) errors for the M2 tidal ellipse are estimated at 1.9 and 1.2 cm s−1 for the major and minor axis, respectively, while the RMS error in ellipse orientation is at 11°.