Where have all the bubbles gone? An oceanographer prays for rougher seas
60° 33.99 S
41° 38.77 W
The Southern Ocean has a dreadful reputation among seafarers. There's no land to get in the way of the westerly winds circling Antarctica, and these furious winds whoosh round and round the continent dragging the surface of the ocean with them. This usually makes life miserable for anyone floating about on top, and so these latitudes have been nicknamed the "Roaring Forties" and the "Furious Fifties". It's not a compliment.
But our time here so far has been astonishing. We have been steaming south across this supposed oceanic hellhole for four days straight and it's been flat calm. Glassy. Not a breath of wind. Not a bubble in sight, except those from the ship's wake. Everyone is delighted except me. I want bubbles! And bubbles come from breaking waves, which are driven by the wind.
The usual ferocious winds are the reason that this is such a good place to study the way that the ocean and atmosphere exchange gases and particles. In the world of oceanic transactions, the Southern Ocean is like the City of London stock exchange. Carbon dioxide, oxygen, sulphur compounds, heat, momentum … many of the commodities of the Earth system change hands here.
The high winds stir up the ocean surface and push along waves that mix up air and water when they break, throwing sea spray up and sucking bubbles down. For example, enormous amounts of carbon dioxide disappear down into the deep ocean here, not to be seen again at the surface for thousands of years.
Just after we left the Falklands, we spent a couple of days studying the start of that process. It's what you do every time you blow on a cup of tea to cool it, but on a much larger scale. As you blow across the teacup, tiny waves form and travel across the cup. Try it. They don't get very far because the "wind" hasn't blown on them for very long. But the stronger the wind is, and the longer it's had to push on the surface, the bigger the waves get.
So we picked an area of coast where the wind was blowing off the land, where we could measure the waves growing and see the CO2 and particle exchanges at the same time. We have a couple of buoys that bob up and down in the waves, and one of them has my bubble resonators on it.
For two days, the buoys bobbed along, recording data. A flock of small albatrosses sat inspecting the cables, convinced that cable ties are albatross food. They kept pecking hopefully at them, just in case. We sat and looked out over the top of the albatrosses, scanning the horizon hopefully for whales, just in case. Hope was not to be rewarded that day.
Then we turned our backs on land and set course south. For two days we steamed through a silent grey world of mist and low clouds. The ocean was flat and featureless, and we could have been sailing off the end of the world. But the ocean itself told a different story.
One of the best things about being on a research ship is that you don't have to rely on your eyes. My workspace is just next to a large bank of computers, and this is where everyone comes several times a day to spy on the hidden world below us. The ocean floor here is about 4,000 metres down, and the ship's acoustic sensors tell us that we're passing over mountain ranges, great plains, and giant sand dunes hundreds of metres high. Since we left port, the water temperature has dropped from around 10°C to –0.5°C (it doesn't freeze because it's salty). The lack of things to look at above water just helps to focus your mind on what's below.
It's starting to dawn on me that this is a truly epic journey, and to be honest, it's as if everything has been far too easy so far. It's time we had some challenges that live up to the environment. I might regret saying that!
The best bit of the week was the moment I realised that my misbehaving bubble detector will work after all. There was some electrical interference between different parts of it, and once one end was in the ocean and the other was in the lab, it all worked perfectly. The relief was tremendous. I'm all set up now to get some great data (if only the wind picks up).
And the second best bit was the excitement of seeing my first proper iceberg this morning. Everything was so quiet and serene, and the ice behemoth was the only thing to see anywhere. The isolation of the iceberg brought home our own isolation, and also the strangeness of the place where we're going. As a scientist, you often know that you're on the edge of the unknown, but it's not often that you get to be there physically. I think this is called living the dream …