RECOVERY LAKE ‘B’, ANTARCTICA– It’s the snow, stupid! …that determines many factors for this traverse, that is.

For instance, the changing snow surface impacts our fuel consumption quite a bit. In softer snow, the four vehicles use much more fuel than when we are going over areas of hard snow. The characteristics of the snow determine how easily we are able to cut blocks out to put in our melters to make water. Sometimes, like in the last two camps, the snow is not very well sintered, or stuck together, and falls apart like shoveling sugar. Other times, we find thick, wind-packed snow that we can readily saw into nice blocks.

For the last few weeks, if anyone has wondered, “Where’s Zoe?,” the answer has been in one of my snow pits. I’m just finishing up my sixth 2-meter deep pit today. Each pit is about 1 m wide, 2 m long and 2 m deep. With an average density of about .38 grams per cubic centimeter, I’ve dug about 1520 kg worth of snow for every pit (that’s over 3000 pounds for the Yanks) – over 9 tons altogether. Not that I’m keeping track, but it is no wonder I’m so tired.

What’s neat is that each pit has its own surprise, and each has been different. It’s been fun seeing what sort of snow and layers I find in each of the pits. The layers help us determine what conditions have been like in the last few 10 to 20 years. Large grains usually mean low accumulation rates, as large grains grow over time as smaller grain sublimate and condense onto larger grains. Old sastrugi and wind crusts, as well as hoar (very large faceted grains from warm conditions and water vapor moving in the snow pack) are also buried. These all help us figure out the puzzle of the past climate in this region, which is tricky since unlike in areas where you get lots and lots of snow and can see the seasonal layering in pits, the area we are in gets very little snow, and any seasonal layering tends to get smeared out over time.

Layering in the top 80 cm of one of my pits, seen in a backlit pit, which is basically two pits with a 20 cm wall in between. The light from one pit left open shines into the second pit, which is covered. In this image, wind crusts (thin lines in the snow), old sastrugi (darker layers), and hoar crystals (very light layers) can be seen.

Music: “I’m Sorry” by Candy Pants.

Maria hauls blocks of snow out of the pit.

We’ve done density, air permeability, thermal conductivity and grain size measurements. We use these measurements to help better predict the movement of gases in the snow, and to compare how these measurements have changed over time.

I made the same measurements in pits at the same location the last two years, placing a bright string tied to bamboo poles at the snow surface each year. I was able to find both strings in the pit—a bright pink from last year and a bright yellow string from the year before– which was exciting.

Maria, Kristina and Elyse worked on drilling 3 meter cores using a hand auger while I finished up a back-lit pit. I’ll do the same measurements I did in the pit on the cores back in the lab in New Hampshire. This gives us replicate measurements. It’s hard to core the upper 2 meters, the snow tends to fall apart. Below that, the snow becomes harder and more compact, and not nearly as fragile.

Maria and Kristina drilling.

A back-lit pit is made by first digging out one pit, then digging a second pit with about a one-foot-thick wall in between the pits. By smoothing out one wall, and covering the first pit, you allow the light from the open pit to filter through the common wall. The layering in the pit really stands out using this method. It also involves digging not one, but two pits. We were able to use the second pit as a lab to make measurements, so it was definitely worth it!

A back-lit pit, clearly displaying the different layers of snow.

Craig Beals, a high school earth science teacher from Billings, Montana who is up here with Jack Dibb and Barry Lefer’s photochemistry group, came by after lunch to visit our pit. Craig is here through the Polar Trec project, which links teachers and researchers. I think he was impressed with our pit—he definitely wasn’t expecting the huge hole that we had dug. He’s six feet tall, and couldn’t reach the top of it standing on the bottom (we’ve been using a ladder to cut out samples from the wall and to make measurements).

The team in the pit. From left, Maria Horhold, Kristina Sorg, me, and Elyse Williamson.

We worked through dinner and late into the night to try to finish everything up before a predicted storm. We were all very tired and hungry by the end of the day, but nothing that a little food and rest can’t fix.

Maria, Kristina, Elyse and I headed out to the Sandy Site, an area where tubes of various lengths, down to 60 meters, were lowered into holes drilled into the snow 5 years ago. Air from the snowpack is then pumped into flasks and measured for a whole host of chemical signals. (The snow here is permeable, open to air flow, until almost 90 meters.)

Inside the mini pit.

The pump that pushes air through the snow. We use it to measure how much pressure it takes to get a given air flow.

Kristina and Maria sampled the air from the tubes today with the help of Andy Clarke, a science tech up here at camp. Lucky for us, he is very familiar with the site, having been the one who installed the tubes there in the first place. Lucky, because my GPS-based navigation and failing memory (I worked at a site a few hundred meters away 2 years ago) led us off at the beginning of the day unsure of the tubes’ whereabouts.

Everything is flat and white out here, and everything– everything– gets buried over time eventually. All that remains of the little ice core drilling site I worked at two years ago is two bamboo flags poking a couple of feet out of the snow.

Elyse taking measurements in the mini pit with the pump and ‘permeameter.’

After sending everyone on a wild goose chase looking for the tubes which were buried in the snow, but were marked by flags, we had a very good day, digging a mini, 1.5 meter pit, and measuring snow density, layering and air permeability. With Andy’s help, Maria and Kristina were able to sample air at two different depths in the snow. Tomorrow, they will sample six more while Elyse and I work in the big pit.

No snowmachines or generators usually means a long, slow walk through the snow pulling a sled piled with gear. This year though, thanks to a group of students at the University of Wisconsin who built a zero-emissions electric snowmobile, we were able to ride to and from our site in style.

The weather was great, and with the help of Tony Cummings, a senior at Georgia Tech here at Summit working with the HOx NOx group (a group of scientists studying the influence of sunlight on snow and atmospheric chemistry,) we were able to dig the big pit, and a smaller “lab” pit that we can work in, in a few short hours. I honestly don’t think that Tony knew what he was in store for, but I also think he enjoyed the good, hard work. Digging is very satisfying, and an excellent way to stay warm.

Let the digging begin.

Elyse peering over the top of the lab pit, with our big research pit in front.

The lab pit is to keep the instruments and scientists out of the wind, and to keep the snow samples cold enough that they don’t melt on warm surfaces or start to change their structure. In the big pit, we are looking at a whole host of physical properties, and how these properties change over time.

Equipment in our lab pit. The grey box on the right is what we call our “permeameter”; it measures how easily air can move through snow. In the white box on the left is a thermal conductivity probe: a needle we push into the snow that heats to a certain temperature then provides us with thermal conductivity readings by measuring the time it takes to heat the snow. The blue box beneath the thermal conductivity probe is a stand for short snow/ice core sections. It isolates samples from the wind– an element that can easily disturb and affect the thermal conductivity measurements.

I had also dug pits here (dragging my gear out in a sled by foot) in the previous two years, and now I can trace the changes in the snow in the intervening time. Last year and the year before, I had put bamboo poles in the snow and tied a brightly colored string across the snow surface. I was able to find both of the strings in the pit, buried by the snow from this year and last. I was relieved and slightly surprised when they both popped up as we were digging.

Kristina stands on one of the pit steps while Maria takes density measurements inside. To take these measurements, we use a tool that cuts out 100 cubic centimeter blocks of snow, then measure the mass of these blocks.

Camp manager Kathy Young and science tech Steve Munsell stopped by our site on the way back to camp after a two hour ski. It was fun to have visitors.

We ended up having to go back out to our site after dinner when things had cooled down a bit. Earlier in the day, we had tried to hand drill a few short cores, but the cores kept getting stuck in the barrel, which was being warmed alarmingly by the sun. Coming out “at night” (it’s 24 hour daylight here now) means colder temperatures, and easier working conditions. Chris, the camp medic, apparently felt sorry for us, and brought out a much needed thermos of cocoa and some after-dinner mints. And then got roped into helping us cover up our pits. A great end to a great day.