HYCOM + NCODA Gulf of Mexico 1/25° Analysis (GOMl0.04/expt_30.1), June 2010 to March 2012

HYCOM is designed as a generalized (hybrid isopycnal/σ/z) coordinate ocean model. It is isopycnal in the open stratified ocean, but reverts to a terrain-following coordinate in shallow coastal regions, and to z-level coordinates near the surface in the mixed layer. This generalized vertical coordinate approach is dynamic in space and time via the layered continuity equation, which allows a dynamical transition between the coordinate types. Like MICOM, HYCOM allows isopycnals intersecting sloping topography by allowing zero thickness layers. HYCOM was developed from MICOM using the theoretical foundation for implementing a hybrid coordinate system set forth in Bleck and Boudra (1981; J. Phys. Oceanogr.), Bleck and Benjamin (1993; Mon. Wea. Rev.), Bleck (2002; Ocean Modelling), Chassignet et al. (2003, J. Phys. Oceanogr.) and Halliwell (2003; Ocean Modelling). HYCOM is maintained as a single scalable/portable source code. The Gulf of Mexico model has 1/25° equatorial resolution and latitudinal resolution of 1/25° cos(lat) or ~3.5 km for each variable at mid-latitudes. It has 20 coordinate surfaces in the vertical.