Just after breakfast in the morning of Saturday 11th April Susanne Hansen (DTU-SPACE) and Jeremy Wilkinson (SAMS) set off from the Canadian Military base, Alert (Ellesmere Island), in our chartered Twin Otter (piloted by Wally Dobchuk and Randy Fehr) in order to locate a site for the GreenArc ice camp. From discussions within the GreenArc scientific consortium we had an approximate location for the ideal camp location, but would the ice conditions be ok?
The Twin Otter aeroplanes are the workhorses of the north (and south). They are ideal for landing on sea ice as they can be equipped with skis, carry a decent payload and only need a short, relatively level, runway (few hundred metres in length). Most important, they can land on sea ice without the need for a runway to be established in beforehand. It is the combination of these features that ensures that these aircraft are flying throughout the Arctic and Antarctic field season.
When establishing a camp on sea ice you are looking for two ice types next to each other, a refrozen lead and thick multiyear ice. A lead is an area of open water that is produced when sea ice drifts apart. In winter the cold temperature ensures that ice forms on the lead and over time the ice grows thicker. This process produces a smooth surface, ideal for a runway. The two characteristics that makes a refrozen lead a good landing strip are its length and thickness. Multiyear ice on the other hand is sea ice that is more than one year old. Being old ice it is thicker and rougher than a refrozen lead. It therefore makes a stable platform for a sea ice camp. Being older it should also have a thicker snow cover and will be less salty (salt drains for sea ice over time), this will be used for our fresh water for the camp.
Once we were at the location of our camp we found that there was a lot of ridge activity (when sea ice drifts together it forms large ridges similar to the way mountains are formed on land). After a bit of searching we found a nice site, ~800 m refrozen lead, >0.8m thick (tested when we landed) next to a number of multiyear sea ice floes. We dropped off some of our equipment, including a radio beacon so we could find the location of the camp and head back to Alert feeling pleased. The next day the ferrying of equipment and the building of the camp will begin in earnest.
Photo: Landing Strip and Camp Site for the GreenArc programme. Jeremy