Submeso scale dYNamics and BIOlogy on steep Slopes – SYNBIOS

The continental slope is an important transition zone between the shallow coastal shelf (50-200m) and the open sea or ocean (1500-4000m). Several dynamical and biological processes occur in the surface layer or the intermediate layers within this transition zone above the continental slope which is often very steep (10-15%). Recent studies have shown that a steep slope configuration may induce complex nonlinear or ageostrophic processes at submeso scale.These submeso scale structures are smaller than the deformation radius and their relative vorticity could be intense. Hence, the impact of the continental slope on the cross-shelf transport and the primary production is still a complex issue for realistic coastal model.
The SYNBIOS project is a basic research project devoted to the dynamical and biological processes over and across steep continental slopes. The complementary expertises of the three partners (LMD, UME-ENSTA and IUEM LPO-LEMAR) involved in this project mix multiple approaches: theory, laboratory experiments, in-situ data analysis and numerical modeling.
One novelty of this project is to show that laboratory experiment can be a cost-effective way of aiding in the development of numerical models. Benefiting from the LMD-ENSTA rotating platform, an efficient tool to study the impact of non-hydrostatic and ageostrophic submeso scale structures (eddies and filaments) on the coastal circulation, modern data acquisition techniques will be developed in order to provide datasets with high spatio-temporal resolution. Inter comparisons between three dimensional laboratory experiments and simplified multi-layer model or more realistic coastal model will validate the main dynamical assumptions and the idealized processes.
The second novelty is to develop an idealized biogeochemical model for coastal area taking into account two trophic chains. Such simplified model is needed to extract the fundamental processes from the complex real system. We will then couple this idealized model with a multi-layer shallow-water model. Hence, we propose to couple individual physical processes with biogeochemical dynamics. Thus we expect to precisely assess the impact of each process on the ecosystem evolution.
The steep slope configuration is relevant for the eastern Mediterranean Sea along the Libyan and Egyptian coast or in the western Arabian Sea along the Oman coast. We will apply our processes studies in these two specific areas were recent data set are (or will be) available from the campaign EGYPT-EGITTO and PHYSIDIEN. A thorough comparison between the in-situ measurements and high resolution coastal models (HYCOM and NEMO MED36) will provide valid and quantitative estimates of the dynamical parameters controlling the cross-shelf transport.
The expected benefit for the defense will be a better understanding of the coastal circulation (and biological activity) along the Libyo-Egyptian and eastern Arabian coasts. The main result for the oceanographic community will be a deeper understanding of the coastal dynamics and the biological activities above steep continental slopes. The scientific results, leading to peer review publications, of the SYNBIOS project (not protected by defense) will be presented and compare with other studies of national and international teams during a final symposium.