By Lora Koenig
I finally made it to our field site on Thursday and we’ve been working super hard since then to make up for our delays. Jay has done an amazing job, drilling 10 hours a day, and I’m glad to report we’re back on schedule. We’ll be done by the end of today, and hopefully we’ll fly back to Kulusuk tomorrow.
We’ve drilled two deep holes: one is 30 meters deep, and the other 60 meters. We’ll lower our thermistor strings (cables with temperature sensors on them) into these holes and leave them there for a year, recording temperatures. We’re also videoing the holes, to see what’s in there.
The aquifer, which is about 12 meters below the surface at the spot where our camp is located (it is shallower or deeper in other parts of the ice sheet), contains more water than we expected. So much, in fact, that we haven’t been able to use our small drill to make holes. We’re only using the big drill, the thermal one. We use the radar to locate the top of the water layer and when we drill, we try to stay about two meters above the aquifer so the drill doesn’t get stuck. Our hands get cold with so much water and at the end of the day we can’t bend our gloves, because they’re encrusted in ice.
We’ve also drilled three other small holes, about 10 meters deep, spread along a 500-meter line. I’m doing density measurements in these holes (and I tell you: it is tiring to pull a sled with the science equipment half a kilometer from our camp to the farthest hole). The density gives us information on the structure of the layers of snow that water goes through to get to the aquifer below. We’ve been able to observe the melt layer cause by last summer’s extreme surface melt event – it’s now 2.5 meters below the surface, which means that this winter has brought 2.5 meters of snow accumulation at this spot.
If we had brought the right equipment, we’d also be doing porosity studies of the cores – but we didn’t, because this is just an initial assessment of the aquifer and we’re traveling light. Still, we’ve tried blowing into portions of the cores to make water come out, so we can see the tiny pathways it used.
On Friday and Saturday, we got the big storm that had been forecasted, but it wasn’t all that bad. The winds were mild and we got 3 inches of new snow. But now, even when it’s sunny, we have 20-knot katabatic winds that are blowing the new snow in our direction and burying our tents.
As I mentioned, the helicopter’s supposed to pick us up tomorrow. We’ll only need two loads this time, in part because we’ve shed 250 kilograms of cargo (by eating our food and leaving behind some of the science equipment, like the thermistor strings), and in part because helicopters are able to carry more load when flying out of the field, since they land on an airway instead of the ice sheet. The problem will be the volume of our gear, not the weight – we’ll try to pack everything as tight as possible.
Once we’re back in Kulusuk, we’ll spend a couple days drying and cleaning our gear, and we’re giving a talk at the local school on Friday. We’re scheduled to fly back to the U.S. on Saturday.
More on our fieldwork (and photos!) when we’re back in Kulusuk!
[Note: This blog post was written by María-José Viñas, based on a satellite telephone conversation with Lora Koenig. Normally, Lora writes her own posts and María-José edits and publishes them. However, there is no Internet 1,500 meters high on the Greenland ice sheet.]