Written by Chris Polashenski
Its been a busy few days here on the SAGE traverse. Since arriving at our fuel cache, we’ve deployed 2 autonomous albedo and weather measuring stations , done 4 science pits, and covered about 160 miles westward. Westward means off of the ice sheet, or at least in that general direction. Our route thus far has had us riding up along the spine of the ice sheet, near its highest elevation the whole way. Now that we’ve made the turn West we are rapidly losing elevation (6200′ today, compared to Summit’s 10350′). As we’ve dropped in elevation our machines, which have been hiccupping and burping their way through our watery gas have gotten happier. No more stopping 3 times a day to crank the water through after stalling. With all this extra air they are running great and we can feel the extra pony’s under the hood.
The snow has changed dramatically too over the past 160 miles. We dipped down onto the ocean-facing slope of the ice sheet into an area with vastly greater accumulation. A year’s snow all along the route from summit to our fuel cache had been 40-60 cm. At our last site it was 118 cm! Perhaps because of the higher snowfall rate, the surface is much smoother than we’ve been driving on. Zoe actually might have been able to “keep her out of the cabbage” here. There also is certainly the temptation with greater available horsepower and smooth surfaces to go a little faster. even though we are stunningly loaded down, fresh off our fuel cache, and with stations still to deploy. This is a temptation I’ve not been entirely able to resist, and Mike and Nate seem happy to oblige with putting their thumbs down on the throttle as well. After two weeks in the choppy seas, a glass smooth water surface like this just can’t be ignored. While not fast by snowmobile standards, seeing us ratchet the speed up from 20- 25mph to careening along at about 35-40 mph with our serpentine circus train must be quite sight.
No one to see it though –the only people, or for that matter signs of people, we’ve seen since leaving Summit were occupying the three airplanes that have passed overhead. One appeared to be a scientific craft, possibly Alfred Wegener Institute’s P-5 which we heard was up here, the other two passenger jets apparently taking a great circle route from Europe to North America. All were thousands of feet above. These homo sapiens sightings were all below station Benson 4-150, though. Nothing since. All told we’ve also seen 9 birds. 2 snow buntings, 2 wheatears, and a flock of 5 snow geese – nice to have animals outnumber people, even in this polar desert where neither really belong. These erratic avian wanders invariably are quite fatigued, and our efforts to feed them something to help them on their way have yet to be taken, but so far each has managed to find the strength to carry on after collapsing near our camp for a couple hours.
Speaking of the changes in the snow, this stuff is HARD. The windslab we’ve been dealing with has been tough, requiring chopping with a steel shovel or sawing into blocks, but honestly the blocks were of too low quality for building much out of. Yesterday’s wind slap was knife-hard, and could be sawn into enormous blocks, which Nate promptly build the Great Wall out of.
Perhaps after we finish our round the-clock station deployment extravaganza there will be enough time one evening for an igloo build. Immediately beneath the winter’s wind slab was a layer of snow that had been thoroughly water-soaked during last summer’s melt. Unlike the isolated percolation tubes and ice layers with relatively soft snow between which we encountered at higher altitude, 70-80%+ of this snow pack had thawed, been water-doused and refrozen into a rock-hard lump. An almost fully saturated snowpack.
Comparing this with the papers written by Carl Benson (who was gracious enough to take Mike and I to dinner before we departed and sign the copy of his report I’m carrying, and referring often) in the 1950’s, the soaked snow zone was at about 3000-4000 ft above sea level in this area. Last summer’s melt apparently crept this elevation up to around 6600 feet. In fact, last summer’s melt transformed the character of the ice sheet. Where vast areas had been “dry snow” snow that never melts at all during the summer, we’ve actually not found a single case of dry snow. Carl divided the ice sheet into zones or “facies” based on the degree of melting that happened there. All these have moved up almost exactly one level. Carl’s dry snow zone is our percolation zone. His percolation zone is our saturated snow zone. While this sort of change had been predicted from last summer’s satellite readings, being the first to put a shovel to it has been quite an experience already. Each night comparing what we see to what Carl saw shows how significant the changes of last summer were. And not just last summer. We’ve also been drilling down 10 m into the ice sheet each night to take a long-term average temperature, just as Carl did 60 years ago. These temperatures have averaged 1-2 C warmer than his. The ice sheet just might be waking up.
Today we actually drove a bit back away from the high accumulation area of the ocean-facing slope, and onto the ‘rain shadow’ side. Digging at first was exactly like our high altitude digging. Easy, soft windpack. Then the pit reminded us we were at much lower altitude where it had been warmer last summer. Part of the reason I’m writing this blog this evening is that Nate – our chief pit digging engineer, is taking a particularly long time blasting, sawing, chipping, and stomping his way through a 4 inch thick solid ice layer, which, it appears, is going to lead him to more solidly melt-soaked and refrozen snow. We may need more shovels.