The internet connection on the Discovery was intermittent, so here are a few blogs that I wrote whilst onboard and also from a few friends about their perspective about what we got up to. I wanted to begin by explaining what a mooring is, as that is a large part of the OSNAP science program that we were on board to help with. In the last blog, Sam explained why we were bobbing around the Atlantic and explained what a mooring is, I want to explain how we recover and deploy one of these moorings.
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| This incredible photo of Pilot whales dancing through the waves was taken by Lewis Drysdale. |
We went from Southampton up and across to the from east to west along the line of moorings, as we went along we did a CTD (see two blogs previous), then a mooring recovery and deployment with a few ARGO floats dropped in along the way.
A mooring is, as Sam Jones explains, "Each mooring consists of tens of instruments distributed along a wire, which is anchored to the seabed and kept vertical by a series of buoyant floats. Due to the depth of the ocean basins, most of the moorings are several kilometers long, so the task of recovering each mooring intact onto a relatively small vessel, downloading data, and redeploying in precisely the same location is non-trivial."
This is the diagram of the arrangement of all of the sensors (instruments) along the wire and where the buoyancy is placed to ensure it stays upright and if one part of it is cut, there is enough buoyancy at that area to keep the rest of the mooring intact.
This is the acoustic release mechanism that is put above the weight on the mooring, it has a unique pinging noise that is programmed before being put into the water, when the vessel is within the distance we send the specific pinging noise into the water which triggers the release that is holding the mooring to the seabed.
Second job, look for the mooring. We also calculated how long it would take to come to the surface by listening to the pings which would ping back what depth it was at.
When it is seen on the surface, the line is then grappled and attached to the winch at the back of the ship.
As instruments and buoys come on board they are fixed to the deck with a chain to take the load, the cable is then winched in, the instruments are taken off, and then the cable wound in until the next load is taken, this is repeated until the end. The weight is the only thing left on the seafloor.
It is a big team effort by all to get everything to work!
Estelle and Lewis program equipment with time, date, and sampling sequence before it is deployed.
At the end of the day, as long as the PSO (principal scientific officer) is happy, then all is good on board.
The moorings that been in the water for two years become full of marine life and what is known as fouling. We take a photo of each sensor as it comes up to encase the fouling causes spikes/bad data.
Scrubbing the gear before it gets smelly!
Whilst you're here, here are a few other things we got into!
We managed a quick tour of the engine room before we left, at the time we were using 3 engines at full power to get us ahead of the storm!
This trip was great for me. I learned so much, especially about matlab and programming!
Lewis taught me how to make this beautiful map. It's going to take me awhile to be good at programming I think, but just going to keep battling on with it!
The most interesting fact is that they use two radars. One radar which is linked to the AIS (automated identification system) to check for ships and objects then during the evening they zoom in on the second display and watch out for 2 mile length fishing line that may not be marked by a light.
My sidekick Kristen who shouted at me in German if I didn't give her the oxygen bottle code haha
A cruise would not be done without a clipboard.
Beautiful weather.
I set up my own gym! The main reason for this is that I usually find the ship's gyms too hot, busy or where the ship rolls around a lot. Raeanne kindly let me borrow her turbo trainer so I took my bike and set up a wee gym near the CTD room. I predownloaded GBR youtube videos which were great, I also downloaded HITS which worked amazingly. It worked well until we got too busy and then we got into a storm so it was a bit to rough for me!
These are ARGO floats, we launched these for the MetOffice. The ARGO talks, are explained on the website as, "Argo is an international program that calls for the deployment of 3,000 free-drifting profiling floats, distributed over the global oceans, which will measure the temperature and salinity in the upper 2,000m of the ocean providing 100,000 temperature & salinity profiles and reference velocity measurements per year. This broad-scale global array of temperature/salinity profiling floats has already grown to be a major component of the ocean observing system. "
Here is a summary of the cruise from our PSO's perspective: We successfully completed all our mooring turnrounds (RTEB1, RTWB2, RTWB3, IB5, IB4 and IB3. We also installed a new mooring: RHADCP at 57° 36.89’N , 15° 24.66’ W, 1083m. This location is the foot of the western flank of the Rockall Plateau. Loic had mapped a jet of the NAC using the glider data (see his paper). This mooring has a near-bottom upward looking Nortek S55 profiling ADCP and microcat. The plan is to analyse how the western and eastern Rockall currents are connected.
Stuart and the techs report that data return has been exceptional: one microcat stopped logging after a fortnight, and we had one or two instances of fouling. Otherwise, all records are 27-months long (this is the longest I have left instruments at sea).
This is a Hovmoller plot of glider missions since 2014. This year has been focused on repeated crossings of the Scottish/European Slope Current at the eastern boundary – basically shuttling back and forward from EB1 onto the continental shelf. These missions are going very well (latest glider was launched in September) and is currently on a mission near EB1. Track the mission here. These missions are providing the slope current properties and transports every couple of days or so. I hope we can demonstrate this is a successful alternative to moorings in this highly fished zone.
The last day was very rough, we had just run away from a big storm in Rockall. We couldn't pack until we got to the Sound of Mull because it was too rolly.
Then we got dropped off at SAMS!!
Even managed to sneak on my bike!
Great two photos taken by Emily Venables!
