HYCOM 1/12 degree page

This site contains real-time nowcast/forecast results from the 1/12° Global HYbrid Coordinate Ocean Model (HYCOM), including snapshots, animations and forecast verification statistics for many zoom regions, mainly sea surface height (SSH), sea surface temperature (SST), surface currents and subsurface temperature and salinity. It also contains direct model-data comparisons.

This nowcast/forecast system is a demonstration product of the HYCOM Consortium for data-assimilative ocean modeling sponsored by the National Ocean Partnership Program and partnering projects funded by the Office of Naval Research, the National Science Foundation, the Department of Energy, and the National Oceanic and Atmospheric Administration. It is run in real time at the Naval Oceanographic Office (NAVOCEANO) Major Shared Resource Center using operational computer time. It uses atmospheric forcing from the NAVy Global Environmental Model (NAVGEM).

The HYCOM Consortium is a participant in the multi-national Global Ocean Data Assimilation Experiment (GODAE), including presence on the U. S. and international steering teams. GODAE is aimed at demonstrating real-time global ocean products in a way that will promote wide utility and availability for maximum benefit to the community.

HYCOM is designed as a generalized (hybrid isopycnal/ /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 global model has 1/12° equatorial resolution and latitudinal resolution of 1/12° cos(lat) or ˜ 7 km for each variable at mid-latitudes. It has 32 coordinate surfaces in the vertical.

The data assimilation is performed using the Navy Coupled Ocean Data Assimilation (NCODA) (Cummings, 2005; QJRMS) system with a model forecast as the first guess. NCODA assimilates available satellite altimeter observations (along track obtained via the NAVOCEANO Altimeter Data Fusion Center), satellite and in situ sea surface temperature (SST) as well as available in situ vertical temperature and salinity profiles from XBTs, ARGO floats and moored buoys. The HYCOM Consortium is also in the process of evaluating other assimilation techniques, the reduced order information filter (ROIF, Chin et al., 1999; J. Geophys. Res.), the ensemble Kalman filter (Evensen, 1994; J. Geophys. Res.) and the singular evolutive extended Kalman filter SEEK filter (Pham et al., 1998; J. Mar. Syst.).

For more information about HYCOM and the HYCOM Consortium, see the HYCOM web page. The source code is also available from this web page.

HYCOM home page

Time line of experiment numbers



Global Ocean Forecast System (GOFS) 3.0



Experiment Number


Date of Update











09 SEP 2010


NOGAPS atmospheric forcing, NCODA mvoi





27 FEB 2013


NOGAPS atmospheric forcing, NCODA 3dvar




20 AUG 2013


 NAVGEM 1.1 atmospheric forcing, NCODA 3dvar






08 APR 2014


NAVGEM 1.2 atmospheric forcing, NCODA 3dvar