Glider observations are assimilated in the Relocatable Navy Ocean Coastal Model (RELO NCOM) with four dimensional variational assimilation (NCOM-4DVAR). RELO NCOM is used by the US Navy to predict the ocean. RELO NCOM is a baroclinic, Boussinesq, free-surface, and hydrostatic ocean model with a flexible sigma-z vertical coordinate.
Several experiments are conducted, using glider observations, altimeter observations, or both data sets. Data sets are further varied by either limiting data to a one-to-one match between satellite observations and glider profiles (typically 5-10 altimeter observations/glider profiles per analysis cycle) or by using all available data (20+ altimeter observations/50+ glider profiles). Further, in the latter experiment, spatially dense glider profiles are assimilated using a new multi-scale data processing and assimilation approach, allowing for many more profiles than standard NCOM-4DVAR, improving the analysis and forecast. Glider observations have the potential to improve model forecasts, particularly for temperature and salinity.