| Assessing the potential improvement of basin scale ecosystem forecasting for
the Mediterranean Sea requires biochemical data assimilation techniques. To
this aim, a feasibility study of surface biomass assimilation is performed
following an identical twin experiment approach. NPZD ecosystem data
generator, embedded in one eighth degree general circulation model, is
integrated with the reduced-order optimal interpolation System for Ocean
Forecasting and Analysis.
The synthetic "sea-truth" data are winter daily averages obtained from the
control run (CR). The twin experiments consist in performing two runs: the
free run (FR) with summer-depleted phytoplankton initial conditions and the
assimilated run (AR), in which, starting from the same FR phytoplankton
concentrations, weekly surface biomasses averaged from the CR data are
assimilated. The FR and AR initial conditions modify the winter bloom state
of the phytoplankton all over the basin and reduce the total nitrogen, i.e. the energy of the biochemical ecosystem.
The results of this feasibility study shows good performance of the system
in the case of phytoplankton, zooplankton, detritus and surface inorganic
nitrogen. The weak results in the case of basin inorganic nitrogen and total
nitrogen, the latter nonperformant at surface, are discussed. |