SA-West Forecast V1.0

The SA-West Forecast product provides a 5 day forecast of the ocean state along the west coast of South Africa, updated daily. This product represents the operational version of the SA-West Hindcast V1.0 product, and forms part of SOMISANA's South African Coastal Ocean Forecast System West (SACOFS).

The model was developed using the Coastal and Regional Ocean COmmunity (CROCO) modelling system. The model curvilinear grid has a variable horizontal grid resolution (1 – 2.5 km) which increases toward the coast. The model has 30 terrain-following (sigma) vertical levels. Model bathymetry is interpolated from digital navigation charts provided by SANHO. Open boundary conditions for our models are obtained from two ~9 km resolution global ocean analysis and forecast products: MERCATOR and HYCOM. Surface forcing for our models is obtained from both the ~25 km resolution GFS and a 4.4 km resolution atmospheric forecast model run operationally by the South African Weather Service (SAWS). The use of two different boundary forcing products and two different surface forcing products allows us to provide a four-member ensemble of forecasts: MERCATOR-GFS, MERCATOR-SAWS, HYCOM-GFS and the HYCOM-SAWS. Each of the ensemble members are additionally forced with tides from TPXO10.

Each ensemble member is initialized once a day, producing output throughout the water column at an hourly temporal resolution for a period of 5 days into the past to 5 days into the future. The SAWS-forced simulations are however limited to a 2.5-day forecast due to the limited temporal availability of the atmospheric forcing.

NetCDF model output files are available as hourly averages throughout the water column. Subsets of the files can be downloaded via Thredds protocol or alternatively entire files can be downloaded via our Mnemosyne file server. The raw model output files are made available along with regridded files which conform to CF-compliant standards. An archive of the operational forecast is maintained by SAEON, and historical forecasts can be made available upon request.