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

System Description

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

Surface forcing is from NAVGEM.

How It's Generated:

1. NRL interpolates the archive files from GLBb0.08 to GLBy0.08 (GLBv0.08 Discontinued on 2020-Feb-18), 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_GLBy0.08_09m11.[ab]): Files containing the model bathymetry on the native grid.

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

"Standard" Fields/Variables :

(2d) salinity_bottom = Salinity
(2d) surf_el = Water Surface Elevation
(2d) water_temp_bottom = Water Temperature
(2d) water_u_bottom = Eastward Water Velocity
(2d) water_v_bottom = Northward Water Velocity

with Vertical Levels ( depth ) : 0.0 2.0 4.0 6.0 8.0 10.0 12.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 60.0 70.0 80.0 90.0 100.0 125.0 150.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1250.0 1500.0 2000.0 2500.0 3000.0 4000.0 5000.0 m

(3z) salinity = Salinity
(3z) water_temp = Water Temperature
(3z) water_u = Eastward Water Velocity
(3z) water_v = Northward Water Velocity

"_ice" Sea Ice Fields/Variables :

(2d) sic = sea_ice_area_fraction
(2d) sih = sea_ice_thickness
(2d) siu = eastward_sea_ice_velocity
(2d) siv = northward_sea_ice_velocity
(2d) sss = sea_water_salinity
(2d) sst = sea_water_temperature
(2d) ssu = eastward_sea_water_velocity
(2d) ssv = northward_sea_water_velocity
(2d) surtx = surface_downward_eastward_stress
(2d) surty = surface_downward_northward_stress

"_sur" surface/diagnostic Fields/Variables :

(2d) emp = surf. water flux [93.0H]
(2d) mixed_layer_thickness = mix.layr.thickness [93.0H]
(2d) qtot = surf. heat flux [93.0H]
(2d) ssh = sea surf. height [93.0H]
(2d) steric_ssh = steric SSH [93.0H]
(2d) surface_boundary_layer_thickness = bnd.layr.thickness [93.0H]
(2d) u_barotropic_velocity = baro. u-vel. [93.0H]
(2d) v_barotropic_velocity = baro. v-vel. [93.0H]

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.