Shelf Sea Biogeochemistry blog

Thursday, 16 April 2015

OMG - Glider glee!

Dr Charlotte Williams, Marine Physics and Ocean Climate, National Oceanography Centre

Today at our main sampling site (CANDYFLOSS) we are deploying our sixth and final ocean glider! Ocean gliders are robots which ‘glide’ up and down in the water whilst taking measurements of temperature, salinity, chlorophyll and oxygen (plus a few more things), and these are what I work with. They send their data back to us when they surface via satellite. The amazing thing about gliders is that we can see the data they are collecting from anywhere with an internet connection as soon as they surface (every 30 mins or so in 100m of water). In fact as I am writing this blog I am checking the data that is coming in from the 4 gliders we have out at the moment! This has been useful for our research cruise as we are trying to catch and sample the ‘spring bloom’. This is where light and nutrient requirements for phytoplankton in the surface become just right in spring, and so we see a bloom in phytoplankton growth. This can be observed by an increase in chlorophyll, which the gliders measure.  

The ‘OMG’ glider being ballasted in the tank. Photo: Jose Lozano.

Sam Ward, the glider engineer from National Marine Facilities, has been working very hard to ensure that the gliders are ready for the water. This includes ‘ballasting’ them in a big tank on the back deck. The gliders don’t have a propeller, they move up and down in the water by changing their buoyancy, which is much less power hungry. Sam has to check how buoyant the gliders are in the seawater that they are being deployed in, as the density of seawater changes according to its temperature and salinity. There will be more to come on how the gliders work in Sam’s future blog! The last glider being deployed today is particularly exciting as this is an Ocean Microstructure Glider (OMG). This glider measures all of the things listed above, but also measures the turbulent kinetic energy dissipation, which is a kind of fancy term for turbulence and mixing. Being able to estimate the mixing in the shelf seas is important because we can then estimate how nutrients and carbon move around.  We will have to see if the dolphins return to see the OMG glider!  

Another glider about to dive under the waves. Photo: Jose Lozano

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