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GOFS 3.1: 41-layer HYCOM + NCODA Global 1/12° Analysis (GLBv0.08/56.3-57.2-92.8) Print
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Title: Global Ocean Forecasting System (GOFS) 3.1 output on the GLBv0.08 grid
Resolution: 0.08° resolution between 40°S and 40°N, 0.04° poleward of these latitudes
Institution: Naval Research Laboratory: Ocean Dynamics and Prediction Branch
Date/Data Range: Jan-31-2017 to Present
Latest Experiment: 92.8
Experiment Sequence: 56.3 -> 57.2 -> 92.8

*Note: GOFS 3.1 output is served on both the GLBu0.08 and GLBv0.08 grids. GLBu0.08 is uniform 0.08° from 80.48°S - 80.48°N, whereas GLBv0.08 is uniform 0.08° between 40°S-40°N, but 0.04° poleward of these latitudes. GLBv0.08 also extends all the way to the North Pole. GLBu0.08 output from GOFS 3.1 (92.8) should be consistent with GLBu0.08 output from GOFS 3.0 (91.2).

What are the major differences between GOFS 3.1 and GOFS 3.0?

System Description

This dataset is created at NRL and provided "as is".

How It's Generated:

  1. NRL interpolates the archive files from GLBb0.08 to GLBv0.08, using isubaregion. Note that this now reads in a “gmap” file that defines the mapping between the two grids. Therefore, isubaregion only does the interpolation (isuba_gmapi, only run once, calculates the actual bilinear remapping weights).
  2. Next, NRL runs archv2ncdf3z on the resulting file using the “NAVO” (NetCDF) output type (interpolated to 40 standard levels). Only five fields are provided: SSH, zonal velocity, meridional velocity, temperature, and salinity. Note: NRL writes out in-situ temperature, not potential temperature. This format also uses short_ints to store fields (which saves space).

Data Assimilation

The system uses the Navy Coupled Ocean Data Assimilation (NCODA) system (Cummings, 2005; Cummings and Smedstad, 2013) for data assimilation. NCODA uses the 24-hour model forecast as a first guess in a 3D variational scheme and assimilates available satellite altimeter observations, satellite, and in-situ sea surface temperature as well as in-situ vertical temperature and salinity profiles from XBTs, Argo floats and moored buoys. Surface information is projected downward into the water column using Improved Synthetic Ocean Profiles (Helber et al., 2013).

Operational Details

The system runs daily at the Navy DoD Supercomputing Resource Center and generates a nowcast out through a seven-day forecast. The output is made available typically within two days after the model run via servers located at the Center for Ocean-Atmosphere Predictions Studies (COAPS), Florida State University (FSU).

Detailed Information

Run configuration (blkdat.input): contains model run configuration information such as time steps, advection scheme, mixed layer submodel, vertical structure, etc.

Model bathymetry (depth_GLBb0.08_??.[ab]): Files containing the model bathymetry on the native grid.

Computational grid (regional.grid.[ab]): Files containing the location of the model grid points.

References

Global Ocean Forecasting System (GOFS) 3.1 website
Contains snapshots, animations forecast verification statistics and model data comparisons.
(Cummings, J.A., 2005)
Cummings, J.A., 2005: Operational multivariate ocean data assimilation. Quart. J. Royal Met. Soc., Part C, 131(613), 3583-3604.
(Cummings, J.A. and O.M. Smedstad. 2013)
Cummings, J.A. and O.M. Smedstad. 2013: Variational Data Assimilation for the Global Ocean. Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications. Vol. II, chapter 13, 303-343.
(Helber, R.W., T.L. Townsend, C.N. Barron, J.M. Dastugue and M.R. Carnes, 2013)
Helber, R.W., T.L. Townsend, C.N. Barron, J.M. Dastugue and M.R. Carnes, 2013: Validation Test Report for the Improved Synthetic Ocean Profile (ISOP) System, Part I: Synthetic Profile Methods and Algorithm. NRL Memo. Report, NRL/MR/7320—13-9364.