Navy Coupled Ocean Data Assimilation (NCODA)

Gulf of Mexico Hybrid Coordinate Ocean Model (GoM-HYCOM)
Navy Coupled Ocean Data Assimilation (NCODA)

The Navy Coupled Ocean Data Assimilation (NCODA, Cummings, 2005) system is an oceanographic version of the multivariate optimum interpolation (MVOI) technique widely used in operational atmospheric forecasting systems. The ocean analysis variables in NCODA are temperature, salinity, geopotential (dynamic height), and velocity. In support of HYCOM, a new analysis variable was added to NCODA that corrects the model layer pressure of the hybrid vertical coordinates. The horizontal correlations are multivariate in geopotential and velocity, thereby permitting adjustments to the flow field. NCODA assimilates all available operational sources of ocean observations. This includes along track satellite altimeter observations and satellite Sea Surface Temperature (SST) retrievals directly from the orbital data using model forecasts as first guess fields. 

The application of NCODA on GoM-HYCOM simulations is described in Kourafalou et al. (2008).


Cummings, J.A., 2005: Operational multivariate ocean data assimilation. J. R. Meteorol. Soc., 131, 3583 – 3604.

Kourafalou V.H., G. Peng, H. Kang, P.J. Hogan, O.M. Smedstad, R.H. Weisberg, M.O. Baringer and C.S. Meinen, 2008. Evaluation of Global Ocean Data Assimilation Experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model. Ocean Dynamics (Submitted).

George Halliwell —