The Mediterranean Sea is a mosaic of geographical, physical and ecological domains with very much diversity and contrasts. The major issue is to develop an in situ observing system, capable of capturing all scales of variability, while avoiding any aliasing effects caused by sub-sampling. This observing system needs to be able to address scales of variability ranging from the very small scale (1km horizontally, few days) to the basin scale (500km, months/years), passing by the mesoscale (15km, weeks/months).
Moreover, in order to build an observation network that would be homogeneous and efficient, it is crucial to better structure the relation between the littoral system, ideal to observe anthropogenic impact, and the open ocean system, a perfect area to study climate change issues. However the range of the space and time scales of the relevant processes is wide. In addition to seasonal or inter-annual variability, the impact of extreme events that control fluxes and budgets in marine ecosystems must be characterized.
This is a very challenging goal, as in situ observing systems have different components complementing information on continental/atmosphere /sea interactions and on the whole water. The field strategy of the MOOSE Network is based on a multisite system of continental/shelf and deep-sea fixed stations as well as Lagrangian platform network to observe the spatio-temporal variability of processes interacting between the coastal-open ocean and the ocean-atmosphere components. (see map figure 2).:
- 2 rivers observatories
- 3 observatories for atmospheric deposition:
- 6 offshore moorings
- 2 HF radars
- Monthly and annual ship transects
- Lagrangian and mobile platforms: 2 glider endurance lines and profiling floats
The use of gliders significantly increases the spatio-temporal coverage for a number of parameters, and provides with a better view of the oceanic variability when deployed simultaneously along the two endurance lines. Gliders are a relatively new technology and autonomously profile from the surface to large depths along sections across basins. Gliders can be considered as ‘steerable’ profiling floats and so, as an active tool able to cover a variety of scales and complement the other components of the observing system. They actually fill the gaps between observations at fixed points, repeating sections in an autonomous way between moorings.
In the MOOSE concept, gliders follow a priori fixed transects (called the “endurance lines”) to observe on the long term key areas as the continental slope, the convection zone and the coastal-open ocean exchange. Two endurance lines are currently operated: Villefranche—Dyfamed-Calvi and Marseille-42N5E-Menorca.