Assimilating Hydrographic Observations into a Nested-Grid Coastal Circulation Model

A numerical scheme was developed for assimilating moored temperature and salinity observations into a coastal ocean circulation model. The main idea of this scheme is to restore the model temperature and salinity to pseudo-observations created from moored hydrographic observations using a pre-determined transfer function. The transfer function is defined as the correlation function between the model variables at each model grid point and the observation site. This assimilation scheme was implemented in a nested-grid coastal ocean circulation modeling system for Lunenburg Bay in Nova Scotia. The hydrographic observations at one of three moorings in Lunenburg Bay are assimilated into the model, and the observations at the other two sites are used to assess the performance of the scheme. In comparison with the unassimilated model results, the data-assimilative circulation model reproduces reasonably well the upwelling/downwelling events in the bay.