Oceanographic nowcasts and forecast guidance are scientific predictions about the present and future states, respectively, of a water body. Nowcasts of water levels, currents, water temperature and salinity incorporate recent (and often near real-time) observed meteorological, oceanographic, and/or river flow rate data and/or analyzed (e.g. gridded) meteorological and oceanographic products. A nowcast covers the period of time from the recent past (e.g., the past few days) to the present, and it can make predictions for locations where observational data are not available. Forecast guidance incorporates meteorological, oceanographic, and/or river flow rate forecasts and makes predictions about the future states of a water body. A forecast is usually initiated by the state of a nowcast.
For SSCOFS, both nowcasts and forecast meteorological forcing is provided by NCEP's North American Mesoscale (NAM) weather prediction model. The model relies on the National Water Model output for the river forcing, ADCIRC (ENPAC2015) for the tidal forcing and the Global Real-Time Ocean Forecast System (G-RTOFS) for the subtidal water level, water temperature and salinity profile along open boundaries.
The SSCOFS grid has 239,734 nodes and 433,410 elements. The vertical grid follows the terrain and consists of 10 spatially varying sigma-layers. The SSCOFS model domain encompasses the Puget Sound, the San Juan Islands, the Strait of Georgia, and the Strait of Juan de Fuca, and extends south along the Pacific Coast to include the Columbia River. The model has an unstructured triangular grid. The resolution varies from ~ 100 m along the shoreline to 500 m in deeper parts of Puget Sound and the Georgia Basin, and increases to 10,000 m over the continental shelf. Resolution in the Columbia River varies between 100 and 200 m.
The SSCOFS runs on NOAA's Weather and Climate Operational Supercomputing System (WCOSS) in a Coastal Ocean Modeling Framework developed by CO-OPS. As a result, the SSCOFS has direct access to NWS operational meteorological products that it needs to run reliably.
Nowcast and forecast guidance cycles are run 4 times a day (every 6 hours). All SSCOFS nowcast and forecast guidance are monitored by the CO-OPS's Continuous Operational Real-Time Monitoring System (CORMS). CORMS provides 24 hour per day, 7 day per week monitoring and quality control of sensors and data in order to ensure the availability, accuracy, and quality of tide, water level, current, and other marine environmental information. CORMS is intended to identify invalid and erroneous data and information before application of the data by real-time and near real-time users.
SSCOFS output is in NetCDF format. OFS output includes time series at the selected locations (stations) at 6-minute intervals, and hourly 3-dimensional
fields for the entire model domain for water levels, currents, water temperature, and salinity.