MFS BULLETIN
Contents
  Assimilated Data
XBT
SST
SLA
ARGO
Forecast
Analysis
Evaluation
Data Access
  Analysis Archive
  Analysis History
  Reanalysis History
Indicators
  Marine Ecosystem Forecast
   

 

AFS BULLETIN

GNOO WEB SITE

MOON WEB SITE

EEA SST

The Mediterranean Forecasting System model
at 1/16 resolution

The Italian Group of Operational Oceanography (GNOO) has developed and mantains the MFS system. MFS is operationally working since year 2000 (Pinardi et al., 2003).

Numeric model implementation

The model code is OPA (Ocean PArallelise) version 8.2 developed by Institut Pierre Simon Laplace, Laboratoire d’Oceanographie DYnamic et de Climatologie, Paris. A detailed description of the code can be found in Madec et al. (1998). The model is primitive equation in spherical coordinates.

OPA has been implemented in the Mediterranean at 1/16 x 1/16 horizontal resolution and 72 unevenly spaced vertical levels (Tonani et al., 2008). The model domain and the bathymetry are shown in below.

The model levels are exactly at the following depths (meters):
    1.472,    4.587,    7.944,   11.559,   15.449,   19.633,   24.133,   28.968,
   34.164,   39.743,   45.733,   52.161,   59.058,   66.456,   74.390,   82.895,
   92.011,  101.780,  112.247,  123.459,  135.467,  148.325,  162.092,  176.829,
  192.603,  209.485,  227.548,  246.875,  267.551,  289.666,  313.320,  338.615,
  365.663,  394.582,  425.499,  458.547,  493.870,  531.621,  571.962,  615.066,
  661.117,  710.311,  762.857,  818.977,  878.906,  942.896, 1011.211, 1084.136,
 1161.970, 1245.031, 1333.657, 1428.206, 1529.057, 1636.611, 1751.292, 1873.549,
 2003.855, 2142.711, 2290.645, 2448.210, 2615.993, 2794.607, 2984.700, 3186.948,
 3402.060, 3630.780, 3873.883, 4132.178, 4406.510, 4697.753, 5006.818, 5334.648

The Digital Bathymetric Data Base Variable Resolution (DBDB-V) has been used to make the model cost line and bathymetry. The bathymetry has been manually interpolated along the Croatian coast by a comparison with detailed nautical chart.

The model domain is closed and in the Atlantic relaxation to climatology is enforced along a boundary strip. We consider an implicit free surface equation (Roullet et al., 2000) so that an explicit water flux can be imposed. In order to maintain the total water budget equal to zero in the overall domain, a water flux correction is imposed in the Atlantic box (see Tonani et al., 2008 for details).

The horizontal viscosity and diffusion is assumed to be bi-laplacian with coefficients of 5 x 109 m/sec and 3 x 109 m4/sec for viscosity and diffusion respectively. The vertical diffusion and viscosity terms are dependent upon the Richardson number. The vertical convective processes are parameterized using the enhanced vertical diffusion parameterization. The model is run with a time step of 600 s.

The water flux in computed toward a monthly mean climatology for the precipitation (CMAP), a monthly climatology for river runoff and the evaporation computed from the atmospheric forcing ECMWF at 6hr of resolution. A sub-model computes air-sea fluxes of momentum and heat from 6 hours operational fields from ECMWF, provided by the Italian National Meteorological Office. In the Atlantic Box, the wind stress is a monthly mean climatology and the heat flux is computed as relaxation toward the MEDATLAS monthly mean climatology.

Data Assimilation system

The data assimilation system is the 3DVAR scheme developed by Dobricic et al. (2008).

The background error correlation matrix is estimated from the temporal variability of parameters in a historical model simulation. Background error correlation matrices vary seasonally and in 13 regions of the Mediterranean which have different physical characteristics. The mean dynamic topography used for the assimilation of SLA has been computed by Dobricic et al. (2005).

The assimilated data include: sea level anomaly, sea surface temperature, in situ temperature profiles by VOS XBTs, in situ temperature and salinity profiles by ARGO floats, and in situ temperature and salinity profiles from CTD.

Forecast and analysis cycle

The analysis is done weekly using a daily assimilation cycle. This means that in order to produce an analysis, the model is run for 24 hours and the analysis is produced at the end of the day assimilating all and only the data available in that time window (filter mode). The daily analysis cycle is done once a week, each Tuesday, producing 13 past analyses and the present day analysis.

Each day a 10 days forecast is produced starting on Tuesday from an analysis and each of the successive six days from a model simulation. The figure below shows the detailed structure of the assimilation and simulation cycle for the daily forecast production.

References

  • Madec G., P. Delecluse, M. Imbard and C. Levy, 1998: OPA8.1 Ocean general Circulation Model reference manual. Note du Pole de modelisazion,Institut Pierre-Simon Laplace (IPSL), France, 11.

  • Roullet G. and G. Madec, 2000: Salt conservation, free surface, and varying levels: a new formulation for ocean general circulation models. J.G.R., 105, C10, 23,927-23,942.

  • Tonani, M., N. Pinardi, S. Dobricic, I. Pujol, and C. Fratianni, 2008. A high-resolution free-surface model of the Mediterranean Sea. Ocean Sci., 4, 1-14.

  • Dobricic, S., N. Pinardi, M. Adani, M. Tonani, C. Fratianni, A. Bonazzi, and V. Fernandez, 2007. Daily oceanographic analyses by Mediterranean Forecasting System at the basin scale. Ocean Sci., 3, 149-157.

  • Pinardi, N., I. Allen, P. De Mey, G. Korres, A. Lascaratos, P.Y. Le Traon, C. Maillard, G. Manzella and C. Tziavos, 2003. The Mediterranean Ocean Forecasting System: first phase of implementation (1998-2001). Ann. Geophys., 21, 1, 3-20.

  • Dobricic, S. and N. Pinardi, 2008. An oceanographic three-dimensional variational data ssimilation scheme. Ocean Modelling, 22, 3-4, 89-105.

  • Dobricic, S., 2005. New mean dynamic topography of the mediterranean calculated fron assimilation system diagnostic. GRL, 32.

  • Pinardi, N., I. Allen, P. De Mey, G. Korres, A. Lascaratos, P.Y. Le Traon, C. Maillard, G. Manzella and C. Tziavos, 2003. The Mediterranean ocean Forecasting System: first phase of implementation (1998-2001). Ann. Geophys., 21, 1, 3-20.

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