Ambient sea-surface temperature and salinity in the Chesapeake Bay are simulated using a version of the Regional Ocean Modeling System (ROMS), adapted for Chesapeake Bay (ChesROMS). ROMS, an ocean model developed and maintained by a group at Rutgers University, is a free-surface, terrain-following, primitive equations model widely used by the scientific community for a diverse range of applications.

ChesROMS uses near-real time observation data to provide model forcing, such as atmospheric momentum and heat fluxes, river outflow and ocean sea level, to simulate salinity, temperature, and other physical (and soon biogeochemical) variables in the Bay in near-real time.

Output from this model is used to produce the sea nettle forecast products.