An Operational Eddyresolving 1/16 Degree Global Ocean Nowcast/forecast System
Abstract
The world's first realtime eddyresolving global ocean nowcast/forecast system has been running at the Naval Oceanographic Office (NAVOCEANO) since 18 Octo- ber 2000 and it became an operational product on 27 September 2001. The system, which was developed at the Naval Research Laboratory (NRL), uses a NRL Lay- ered Ocean Model (NLOM) with {1/16}(circ) resolution and 7 layers in the ver- tical including a mixed layer. Real-time satellite altimeter sea surface height (SSH) from Topex/Poseidon, ERS-2 and Geosat-Follow-On provided by NAVOCEANO's Altimeter Data Fusion Center (ADFC), are assimilated into the model. The large size of the model grid (4096times2304times7) and operational requirements make it necessary to use a computationally efficient ocean model and assimilation scheme. The assimilation consists of an optimum interpolation (OI) deviation analysis of SSH with the model as a first guess, a statistical inference technique for vertical mass field updates, geostrophic balance for the velocity updates outside of the equato- rial region and an incremental updating of the model fields to further reduce grav- ity wave generation. A spatially varying mesoscale covariance function determined from Topex/Poseidon and ERS-2 data is used in the OI analysis. The sea surface temperature (SST) assimilation consists of relaxing the NLOM SST to the Modular Ocean Data Assimilation System (MODAS) SST analysis which is performed daily at NAVOCEANO. Performance statistics after more than a year of daily runs and weekly 30 days forecasts, will be discussed. The statistics show that the model has predictive skill of the mesoscale variability for at least a month for many regions of the global ocean. The model nowcast is routinely compared to unassimilated data. Realtime and archived results from the model can be viewed at the NRL web site http://www7320.nrlssc.navy.mil/global_nlom.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.1058S