We had gone to a night-time drilling schedule because of the problems the sun was creating by getting the core stuck due to melting snow. I say “we” in the royal sense, as it is really Bella, Terry, Darek, and Ryo that are doing all of the coring work. I walk over every once in a while and try to look official, but my time has been mostly occupied by sorting gear, finding tools or solutions to minor problems, etc, though I did have the chance to get some photography prep work done that I had to blow off in Fairbanks in the time crunch. Anyway, drilling commenced about 9PM after a nice spaghetti and meatball dinner, at which point I went to bed, and proceeded until 4AM when water was struck.
Though water at this depth was unexpected, we are drilling at this location because we had some strong suspicions that things were going on here that we didn’t understand fully. In 1957, a hole was drilled not far from ours that showed the ice temperature was only about -1C, nearly to the bottom. This was surprising because the mean annual air temperature here is about -12C, and so the ice “should” be about this too. The difference arises because of surface meltwater. In summer, all of the snow surface of McCall Glacier melts somewhat, unlike the summit of Greenland or most of Antarctica which have no surface melt. This melting snow then either travels over the surface in small streams, or drips down into the snow pack. If the snow pack is below freezing, the meltwater may refreeze, typically forming layers of ice, which are easily seen in snow pits. But when water turns to ice – that is, when it changes from a high energy state to a lower energy state – it must release energy in the form of heat to do so. We call this release energy ‘latent’ heat because the temperature of the water/ice doesn’t change when it is released, unlike ‘sensible’ heat which can be sensed with a thermometer. This latent heat energy then warms the snow pack, such that by the end of summer all of the accumulated snow (as much as 30 years worth that has not yet been compressed to glacial ice) is no longer at the mean annual air temperature but rather somewhere near the freezing point. Thus all of the ice beneath this “thinks” that the surface temperature is near freezing too since it never gets a chance to feel the coldness of winter before the warming due to refreezing occurs.
Clearing ice off the barrel with a heat gun.
Clearing ice off the barrel with the old fashioned way.
Jason lowering the borehole camera into the hole.
Matt trying to watch the camera action in the bright sun.
The camera covered in frozen slush, not very useful.
Because of this prior work, we knew that the ice here would be fairly warm, but there is a big difference between ice at -1C and ice at 0C. Namely, ice at 0C can coexist with liquid water, whereas this is much more difficult to colder ice. So to find liquid water within the glacier at this location is both surprising and interesting to us, and gives us something to think about as we continue drilling.