Hydrodynamic and Biogeochemical Modeling

 

One of the most important issues in Operational Oceanography is modeling the marine environment in order to assess past changes (hindcast) and foresee future evolution (forecast).

In Oceans Catalonia International SL, modeling is the result of innovative research carried out by its scientists for more than 40 years. Various hydrodynamic and biogeochemical models have been developed by the members of the Group since the early simulation model developed by A. Cruzado:

  • Coastal upwelling in NW Africa. 1976. Cruzado, A. Ph.D. Thesis, Univ. de Barcelona.
  • Simulation model of primary production in coastal upwelling off Western Sahara. 1982. Cruzado, A. J. Cons. perm. int. Explor Mer. 180, 5-6.
  • Modelling the deep-chlorophyll maximum: A coupled physical-biological approach. 1992. Varela, RA.; Cruzado, A; Tintore, J; García Ladona, E. Journal of Marine Research, 50 (3), 441-463.
  • A simulation analysis of various biological and physical factors influencing the deep-chlorophyll maximum structure in oligotrophic areas. 1994.Varela R. A. ; Cruzado A.; Tintore J. Journal of Marine Systems, 5 (2), 143-157.
  • Modelling primary production in the North Sea using the European Regional Seas Ecosystem Model. 1995. Varela, RA; Cruzado, A; Gabaldón, JE. Netherlands Journal of Sea Research, 33 (3-4), 337-361.
  • A model of phytoplankton growth on multiple nutrients based on the Michaelis-Menten-Monod uptake, Droop's growth and Liebig's law. 1997. Legovic, T; Cruzado, A. Ecological Modelling, 99 (1), 19-31.
  • Dynamics of oligotrophic pelagic environments: North western Mediterranean sea and subtropical north Atlantic. 2002. Bahamón, N. Ph.D. Thesis, Univ. Politèc. Catalunya, pp. 172
  • Modelling nitrogen fluxes in oligotrophic environments: NW Mediterranean and NE Atlantic. 2003. Bahamón, N; Cruzado, A. Ecological Modelling, 163 (3), 223-244.
  • Chlorophyll a and nitrogen flux in the tropical North Atlantic Ocean. 2003. Bahamón, N; Velásquez, Z; Cruzado, A. Deep Sea Research Part I, 50 (10-11), 1189-1203.
  • Modeling the circulation in the Northwestern Mediterranean Sea with the Princeton Ocean Model. 2007. Ahumada, M.A., Cruzado, A. Ocean Sciences, 3 (MFSTEP Special Issue), 77-89.
  • Two different 3D pelagic ecosystem models for the NW Mediterranean Sea. Validation with MERIS data and intercomparison. 2007. Bernardello, R., Baird, M., Ahumada, M. A., Cruzado, A. 6th European Conference on Ecological Modelling, ECEM '07, Trieste (Italy).

Numerical modeling is always a complicated issue not only because the tools used not always adapt to the specific conditions required, but because realistic coastline and bathymetry must be properly obtained and forcings as representative as possible of actual conditions must be used.

In the old times, modeling also required programming since there were no tools available. At present, there are a number of public domain software packages that can be adapted to any problem with relative ease.

The modeling Group of Oceans Catalonia International SL has been using the Princeton Ocean Model (POM), developed at Princeton University (USA), for hydrodynamic modeling while for biogeochemical modeling, its own BLANES model is used. Other packages such as ERSEM or BMF have also been used.

In the Forecast/Reanalysis section, the Ahumada/Bernardello version of POM/BLANES for the NW Mediterranean Sea has been used. Forcings were taken from the perpetual year MFSTEP experiment and correspond to climatological monthly means. Daily samples taken at noon of every day are used in the forecast. Spatial resolution is 1/16 of a degree (about 7 km) with 32 layers in sigma coordinates.

New developments are at present taking place:

  • A new parallelised version of POM is being run in large cluster processors. A high resolution scheme is being used with 1/20 of a degree (about 5 km) and 73 sigma layers. Forcings are directly taken at 6 hour intervals from ECMWF models (re-analysis and forecast) and one week forecast is produced.
  • Comparison of model surface temperature with SST from MODIS satellite provides an excellent tool to validate an 8-year simulation of the hydrodynamical model.
  • Model surface Chlorophyll a is also compared to water color MODIS observations.
  • Data assimilation, especially of in situ observations done at the OOCS is the next step in model development.
  • Nesting of higher resolution coastal models aimed at obtaining applications of environmental interest are also being developed for various uses, among others:
    • sewage dispersion
    • oil spills
    • drifting objects
    • jellyfish dispersal