Gliders are small autonomous underwater vehicles which were developed to carry out in-situ observations of the upper 1km of the ocean filling the gaps left by the existing observing systems (see the EGO website for more information). They have a small size (about 1m50 long and 20cm in diameter) and their weight is around 50kg in air (and +/-200g in water). They enhance the capabilities of profiling floats by providing some level of maneuverability and hence position control. They perform saw-tooth trajectories from the surface to the bottom of the ocean or maximum depths of typically 100-1000m (and recently 6000m depth), along re-programmable routes (using two-way satellite link).
Underwater pictures of gliders deployed in the framework of MOOSE
There is around ~2-6 km between surfacing when diving to 1km depth. They achieve vertical speeds of 10-20cm/s and forward speeds of 20-40 cm/s thanks to a ballast pump, wings, and rudders, and can be operated for a few months before they have to be recovered They can record temperature, salinity, pressure data and depending on the model some biogeochemical data, such as dissolved oxygen, different fluorescences and/or optical backscatters by using miniaturized sensors on-board. By comparing their GPS fixes with underwater dead-reckoning, they can also measure the average currents over their dives.
(see also ”how does a glider work?”).
If glider operations in the Western Mediterranean Sea started in 2005, gliders have started to be deployed regularly in 2010 in the framework of the MOOSE observatory (MOOSE), thanks to the setup of national glider facilities at DT-INSU/Ifremer (http://www.dt.insu.cnrs.fr/gliders/gliders.php) and with the support of the European project FP7-PERSEUS, along two endurance lines, so-called:
- MooseT00: Nice-Calvi (Ligurian Sea)
- MooseT02: Marseille-Menorca (Gulf of Lion)
MOOSE glider trajectories between along the 2 endurance lines
A close collaboration with SOCIB in Spain in the framework of which additional endurance lines (through the Balearic Channels in particular) are operated allow us to monitor the oceanographic variability of this basin over a continuum of spatial and temporal scales.
Near real time glider data visualization
- Northwestern basin: http://www.ego-network.org/dokuwiki/doku.php?id=public:obs-med-western
- MooseT00: http://www.ego-network.org/dokuwiki/doku.php?glider=Milou,MooseT00_27
- MooseT02: http://www.ego-network.org/dokuwiki/doku.php?glider=Sg509,PerseusT02_03
Near real time data access: http://www.coriolis.eu.org/virtualys/externalimage/2973/large