PATRICK MARCHESIELLO
Tel/Fax: +687 26 07 24
Patrick.Marchesiello@noumea.ird.nc
 IRD Noumea Center
BPA5 - 98848 Noumea Cedex
New Caledonia

EXPERIMENTAL OCEAN FORECAST
AROUND NEW CALEDONIA
DISCLAIMER: Our main goal is to improve our regional modeling capability through validation using any available information, either from professionals or the general public experience. The achievement of this goal involves the presentation of experimental graphical products, which are provided "as is" without warranty of any kind, including any implied warranties of merchantability or fitness for a particular purpose.

EEZ OF NEW CALEDONIA
 SOUTHWEST PACIFIC
REGION ROMS EEZ New Caledonia circulation ROMS SW Pacific circulation

Collaborator: PIERRICK PENVEN (IRD/ECO-UP, University of Cape Town, South Africa)

Links to observation, analysis and forecast

DESCRIPTION OF ROMS FORECAST METHOD

ROMS-AGRIF, the nested version of The Regional Oceanic Modeling System, is setup for operational regional modeling following Marchesiello et al. (2008, MERCATOR Newletters, July 2008). The strategy for a nowcast/forecast cycle is as follows. A first week of simulation (from t0-7 to t0, t0 being the present time) in hindcast mode is run using interpolated data from the global MERCATOR 1/4 degree, daily product for lateral boundary conditions and global NCEP operational 6-hourly GDAS product for surface forcing. A ROMS restart file (from a previous forecast) is used for initialization at time t0-7, while nudging assimilates the MERCATOR global ocean data (with a nudging time-scale of 15 days). This provides a nowcast at t0, which is the initial condition of the forecast run of the following week. The forcing in the forecast run is interpolated from MERCATOR and GFS. A Shell script (make_roms_forecast.sh) manages the whole procedure: download and pre-processing, hindcast and forecast simulations, post-processing and transfer of graphics to the web page, data storage and preparation of the next nowcast/forecast cycle. To improve the system, the ROMS-AGRIF build-in 2-way nesting procedure will be used for local refinement. In this case, the results may also be improved in the future by assimilation of small-scale data.

OCEANIC MERCATOR ASSIMILATED PRODUCT

The Global 1/4 degree operational ocean system ( PSY3V2) from MERCATOR is a global ocean data assimilation system. PSY3V2 employs the NEMO OGCM (configuration ORCALIM025). There are 50 levels in the vertical, with 1-m resolution within 20 m of the surface. The model is forced by the ECMWF ERA40 (1992-2002) global reanalysis for wind stress, heat flux, evaporation, and precipitaton. The assimilation system (SAM2V1) is based on a reduced Kalman filter (SEEK). It corrects the model mean sea level with the RIO (V5) product, sea level anomalies with SLA altimeter data (JASON, Envisat and GFO), sea surface temperature with combined satellite/in-situ half-degree RTG-SST analysis, and temperature/salinity profiles using the CORIOLIS in-situ data base.

ATMOSPHERIC GFS FORECAST

The NOAA National Centers for Environmental Prediction (NCEP) Global Forecast System/Global Data Analysis System (GFS/GDAS) is the decision support tool used by NOAA for medium-range numerical weather prediction. The forecast model, GFS, is a global spectral model with meteorology data assimilation using the Gridpoint Statistical Interpolation (GSI). GFS is run four times per day (00 UTC, 06 UTC, 12 UTC, and 18 UTC) out to 16 days. For the first week, computation is done at a resolution of about 35-km. The GFS data is then gridded for users on a global 0.5-degre resolution grid.