Data Assimilation in the IAS using IS4DVAR in ROMS

A brief introduction to using data assimilation in ROMS with an application in the Intra-Americas Sea. The Intra-Americas Sea is an interesting oceanic region comprised of deep basins with complex bathymetry and geometry. It is a well- constrained region of the North Atlantic with land mass boundaries along the western and northern extents. The Caribbean region is highly dynamic, but is well sampled by a long, overlapping time series of both satellite and in situ physical oceanographic measurements. Using the Regional Ocean Modeling System (ROMS), we have developed a real-time data assimilation system utilizing both satellite surface observations and in situ ship measurements to generate the best model state for the current day. Utilizing the numerous tangent-linear solutions from the data assimilation system, we generate a set of orthonormal perturbations to apply to the generated initial conditions to generate a forward, two- week predictive ensemble. This assimilative/prediction system is now running automatically in an experimental operational capability aboard a ship making regular trips across the region. We will be discussing the algorithmic setup and preliminary results from this experiment.

Brian Powell, UCSC
Hernan Arango, Rutgers
Andrew Moore, UCSC
E. Di Lorenzo, Georgia Tech
Ralph Milliff, CORA
Dave Foley, NOAA/PFEL