Boeken

Sunday, May 11, 2008

On the ice - Part 4

Sunday May 4, 2008

Forget about the image of the pole cap as a flat, uniform, boring ice plate. The sea ice is a sleeping, seductive and unpredictable monster. Today, we went by snow scooter a bit farther from the ship than before. We parked the snow scooter on a – at first sight – flat piece of ice.

But even here, I can see differences from meter to meter. Here, the snow is a bit thicker, there a bit thinner; here it is a bit whiter, there a bit darker; here the wind has blown small ribbles in the snow, there some bigger ones. They look like small sand dunes.

The researchers start their experiments. Jens Ehn is measuring the light reflection by the snow and the ice. A little further away, Natalie Asselin is making a hole in the ice. When that’s done, Véronique Lago lowers an instrument tied tot a sixty-meter rope into the sea water. She measures the temperature, the pressure and the salinity of the first sixty meters of the seawater below our feet.

Meanwhile, I look around. Beautiful pressure ridges are sticking out of the ice some tens of meters away. I take my camera and walk towards the ridge. The terrain gets rougher and rougher. Sometimes I sink half a meter into the snow. When I am almost there, Jens shouts that I have to come back. He is our gunman, and I don’t carry one (neither do I know how to shoot).

As soon as the experiments are finished, we drive by snow scooter to the ridge that I saw. Big, rectangular pieces of ice stick up. White at the top, more and more blue towards the bottom. Some of them stick out so far, that ice caves have formed underneath. I lie on my belly to look inside one of the ice caves. Against a fully, eye blue background, water is dropping from tens of small ice stalgtites.

The sun is shining, and it is only -8 Celsius. Master student Natalie Asselin lies down on a pressed up ice block and takes a sunbath. We try to throw snowballs, but it’s not the type of snowball snow. The snowballs fall hopelessly apart in the air.

From a distance I can see a tower made of ice cores. Master corer Benoit Philipe has built the tower two days ago. On one day he managed to make a record number of 109 ice cores. He is already coring for many days. No wonder the pole is losing ice, is the joke that soon went around. From the core pieces that he didn’t use, he built the ice tower.

I can feel at the snow and the ice that it is getting spring. De snow gets stickier, the top layer of the ice softer. I take a piece of an ice core and suck on it. Tastes salty. This is young ice. I look at it’s structure, and I see some thick droplets of brine. Droplets with a high salinity. When the seawater freezes, the salt is expelled from the ice crystals. It gets trapped in pockets between the crystals. The brine stays liquid, as a much lower temperature would be needed to freeze them.

The longer the ice stays frozen, the bigger the chance that the brine manages to escape, leaves holes in the ice behind, and lands in the seawater. There, it plays an important part in the ocean circulation. It makes the salinity of the sea water higher, making the water heavier. The heavier water sinks and can transport big amounts of water over hundreds of kilometers.

When I tell Jens that, until my preparation for the Amundsen trip, I imagined the pole cap to be a flat ice pancake, he tells: “That’s the way the ice modelers still look at it.” But OK, they have to. Modeling is simplifying. The art is to undress the sea ice in such a way that you can model it mathematically, but that the results still look like describing real sea ice.

The ice is getting spring fever. It opens up more and more. At the bottom of the sea ice the ice algae start their blooming season. In the last couple of days we have seen the first birds arriving. My Inuit room mate Roger Memorana recognizes and counts them all. A black guillemot was the first to arrive. Next were the glaucous gull and the snow bunting.

In the next months to come, more and more colorful life will arrive to the sea ice, the flaw leads and the polynyas. It’s a big pity that I have to leave in three days.