This site contains real-time nowcast/forecast results from the 1/12° Arctic Cap
Nowcast/Forecast System (ACNFS), including snapshots and animations of ice thickness, ice
concentration, ice speed and drift, sea surface height (SSH), sea surface temperature (SST)
and sea surface salinity (SSS).
ACNFS is a coupled sea ice and ocean model that nowcasts and forecasts conditions in all sea
ice covered areas in the northern hemisphere (poleward of 40°N). In ACNFS, Community Ice
CodE (CICE) (Hunke and Lipscomb, 2008) is used as the ice model and is coupled with HYbrid
Coordinate Ocean Model (HYCOM) (Metzger et al., 2008, 2010). Ice and ocean fields are passed
between the two models hourly using Earth System Modeling Framework (ESMF) (Hill et al.,
2004). The ice and ocean models are set up and coupled on the same 1/12° horizontal grid.
Resolution is approximately 3.5 km near the North Pole and 6.5 km near 40°N. A plot of
the grid resolution can be seen
forcing in ACNFS is obtained from the Fleet Numerical Meteorology and Oceanography Center 3
hrly 0.5° NAVy Global Environmental Model (NAVGEM).
The data assimilation is performed using the Navy Coupled Ocean Data Assimilation (NCODA)
(Cummings, 2005) 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 ice concentration,
satellite and in situ SST as well as available in situ vertical
temperature and salinity profiles from XBTs, Argo floats and moored buoys using a
3-Dimensional VARiational analysis (3DVAR) scheme.
For more information about the validation of the ACNFS, see (Posey, et al., 2010). For more
information concerning the models see the links below:
Cummings, J.A., 2005: Operational multivariate ocean data assimilation. Quart. J. Royal
Met. Soc., Vol. 131, pp 3583- 3604.
Hill, C., C. DeLuca, V. Balaji, M. Suarez, A. da Silva, 2004: The Architecture of the Earth
System Modeling Framework. Computing in Science and Engineering, Vol. 6, pp 18-28.
Hogan, T.F., T.E. Rosmond and R. Gelaro, 1991: The description of the Navy Operational
Global Atmospheric Prediction System's Forecast model (NOGAPS). NOARL Report 13, Naval
Research Laboratory, Stennis Space Center, MS.
Hunke, E.C. and W. Lipscomb, 2008: CICE: The Los Alamos sea ice model, documentation and
software user's manual, version 4.0. Tech. rep. LA-CC-06-012, Los Alamos National
Laboratory, Los Alamos, NM. (http://climate.lanl.gov/models/cice/index.htm).