Arctic Ocean Forecast - TOPAZ3 North Atlantic fields

NERSC-NATL-TOPAZ3-FOR

Ocean forecast

Gridded (analysis)

General description : Operational Ocean General Circulation Models describe routinely the 4D evolution of the physical ocean and sea-ice variables such as: temperature, salinity, currents, sea level height, sea-ice thickness etc... The TOPAZ system has provided analyzes and forecasts for the Atlantic and Arctic Basins since 2003, assimilating satellite data (altimetry, SST, sea-ice concentrations).
Processing information : TOPAZ uses the latest version of the Hybrid Coordinate Ocean Model (HYCOM) developed at University of Miami (Bleck 2002). HYCOM has been coupled to a sea-ice model. Ice thermodynamics are described in Drange and Simonsen (1996) and elasto-visco-plastic rheology in Hunke and Dukowicz (1997). The model grid obtained by comformal mapping has fairly homogeneous horizontal spacing (between 11 and 16 km) and 22 hybrid layers in the vertical (z-isopycnal). TOPAZ uses the Ensemble Kalman filter (Evensen 1994, 2006) to assimilate remotely sensed sea level anomalies, sea surface temperature, sea-ice concentration and sea-ice velocities and processes a one-week hindcast and ten days forecasts every week. The output files are stored as daily averages.The numerical ocean output served on the opendap consists of daily mean fields interpolated onto standard grids in NetCDF COARDS-CF format. The 3D currents (U, V), temperature and salinity are available. Additional 2D fields are also available (Sea-ice thickness and concentrations, SSH, mixed layer depth, etc.). All the data (input and output) of TOPAZ are archived on the native model grid and the access to real-time as well as to all the archived passed data is possible on demand. Ancillary data and diagnosed quantities (such as high resolution data along sections or at given location) are also available.
Description of observation methods / instruments : N/A
Quality/accuracy/calibration information : The quality of the bulletin isweekly assessed and based on human expertise - Visual check- Metrics computation- Assimilation diagnosis, including distance between model and observations.
Suitability, Expected type of users / uses : 7 main uses are targeted:

1. Lateral boundary conditions for regional or coastal forecasting.
2. Analyses and forecast of 3D currents and sea-ice for the offshore oil and gas industry.
3. Initialization of climate forecast (decadal, seasonal)
4. Coupled forecasting of ocean biogeochemistry (primary production)
5. Evaluation of the ocean observation network and recommendations.
6. Ocean analyses for environmental agencies regular assessments.
7. Sensitize and educate the public at large.

• ocean_barotropic_streamfunction,m3 s-1,CF
• ocean_mixed_layer_thickness,m,CF
• sea_floor_depth_below_sea_level,m,CF
• sea_surface_height_above_geoid,m,CF
• sea_water_potential_temperature,K,CF
• sea_water_salinity,1e-3,CF
• sea_water_x_velocity,m s-1,CF
• sea_water_y_velocity,m s-1,CF
• surface_downward_eastward_stress,Pa,CF
• surface_downward_heat_flux_in_sea_water,W m-2,CF
• surface_downward_northward_stress,Pa,CF
• water_flux_into_ocean,kg m-2 s-1,CF

Regional scale

1/8 degree

from 0 to -4000 meters.