A little science

It's been a week already! Who would've thought? That is one of the strange things about being at sea – no television, no radio, no work, no school, nothing to remind you what day of the week it is. Still, after a week, it's great to see everyone still cheerful and happy to be here. Every time we spot something new everyone still gets very excited.

So we thought that after a week of icebergs and penguins, it was time to tell you a bit more about why we're here and what we're doing. Our ship, the RRS James Clark Ross is travelling along two survey lines off to the East of the Antarctic Peninsula. We've chosen these two particular lines as they had already been used on previous trips. This gives us the possibility to compare the old data with the new data and get a feel for how everything changes over time.

Drifters are thrown overboard and immediately start drifting with the currents, giving us a map of where the water goes.

While travelling along these two lines, we deployed Andy's drifters. The drifters are basically a float with a long sock-shaped parachute dangling 15m below the surface. As the currents pull the sock, the float is dragged along and relays its position through a satellite network. Some of them even have the ability to transmit back the temperature and the salinity (the saltiness of the water) of where they are. While the drifters go along their merry way, the ship goes back and forth doing CTD casts. The CTD rosette is a large metal frame with big bottles attached and a sensor package. As we lower the CTD to the bottom of the sea (several thousand meters deep, much much more than the highest mountain in the UK), the sensors measure temperature, salinity, as well as the amount of light reaching those depths and an estimate of chlorophyll which can help us guess how much phytoplankton there is. Phytoplankton are tiny single-celled algae that you find all over the world. As the CTD comes back up, we can close the bottles and trap some of the deep water. Once we bring it up to the surface, we can do measurements by hand to make sure that what the sensors are telling us is correct.

The CTD is lowered to the very bottom of the sea where only the most advanced submarines in the world would even dare to go.

Our first look at water temperature over the continental shelf and slope.

And finally, the Seagliders are sent off to get measurements in places where we don't have the time or the ability to go and will stay out collecting data for a whole 5 weeks after we return home. The Seagliders are excellent tools because they can measure the same things as the CTD, but also measure the currents like the drifters. And to make it even better, they can last for months and months and you can leave them out without having to supervise them.

Once we collect all the measurements, we can then start creating “maps” of the water masses. The oceans aren't just a big puddle with waves on the top. Because they are so large, you get massive differences between different areas. While some areas are warm, sunny and calm, others can be covered by ice or very cold. These differences can change the water, making it heavier or lighter. This means that in many areas you have water sinking while in others water floats up, and similar things happen over huge distances; these are currents. To figure out what happens and where, we measure the chemical properties of the water. This is like a fingerprint: it is different for every water mass. By looking at this chemical fingerprint we can track where water masses go and figure out the different currents involved.

Why we want to look at these current is a very different question. Currents cause a lot of mixing and create very dynamic environments. This is often where you get the most life. This microscopic life, feeds the small fish, which feeds the bigger fish, which feeds the even bigger fish, the sharks, the whales and us. It's important to understand what's happening as this allows us to see what happens and understand if things are changing, whether it be due to pollution, changes in the climate or just completely naturally. The other reason is we're just curious and we like to understand things no one really knows much about!

These regions are where a huge part of the ocean's life lives and understanding what goes on can help us understand where animals like krill grow, which then feed other animals like these humpback whales that decided to come check out the ship and pose for some photos!

Back to the journals.