February 15th, 2012 by Maria-Jose Viñas
By Lora Koenig
Lora and Ludo, back in the office at NASA Goddard, point at where in Antarctica their snowmobile traverse took place.
I am feeling a little sad as I write this post. I always do when writing the last post of a research season. Being able to share my science is one of my favorite parts of my job. I assume some of you looked at our blog’s photos and thought “they’re crazy,” while others started planning how they too could get to Antarctica. Either way, I hope you have found this blog interesting, entertaining and inspiring and that you learned a bit about how we measure snow accumulation in Antarctica.
For some quick updates: Jessica, Randy, and Clem are back home in Utah, Michelle is on her way back to Copenhagen, and Ludo and I are back at Goddard Space Flight Center in Maryland. Our radar gear has already arrived from Antarctica and has been packed away in the lab to wait for another season. Our ice cores made their way from WAIS Divide Camp to McMurdo a few weeks ago but it is uncertain if they will make it back to the U.S. this year: There has been a problem with the ship going to McMurdo, which just passed an inspection in New Zealand and is now making its way to Antarctica. We are hopeful that the cores will make it on the ship northbound but have been told not to expect it. Just another example of the logistical difficulties of working in Antarctica! If the cores do not return this year, it will not affect the science, just our patience. The cores will stay in a freezer until the next ship comes in February 2013. But we’re keeping our fingers crossed that our cores are loaded on this year’s ship.
My next field season, and therefore field blog, is not set right now but please continue to follow online the work that my colleagues and I do at our lab’s website, on Twitter, and through the NASA Visualization Explorer app for the iPad. Results from this research will be posted through those outlets.
Also, the complete collection of our expedition’s blog posts is here.
Until next time, stay warm!
February 9th, 2012 by Maria-Jose Viñas
By Ludovic Brucker
Once the traverse was over and we had drilled nine snow cores (with a combined length of 156 meters, or 512 ft), the next step was flying to each of our drilling sites and bringing the cores to the West Antarctic Ice Sheet (WAIS) station to store them before they are shipped (hopefully soon!) to McMurdo and then to Bringham Young University for our analyses.
Three days before we completed our traverse, Michelle initiated talks with the flight schedule team to coordinate pickup dates for the ice cores. Usually, there are three planes operating from Byrd Station: two Twin Otters and a Basler. However, during the weeks following our traverse, there was only one Twin Otter available and it had to be shared with other scientific missions. In the end, the flight schedule team decided to assign us a flight on December 30th .
However, on the 28th, the morning following our arrival to Byrd, the Twin Otter pilots’ weather check at 7 AM revealed that it was impossible to fly another scientific mission planned for that day due to possible fog. They decided they would check the weather forecast again at 10 AM and probably fly our mission instead.
Meanwhile, Randy and Jess were reading in their tents, Clem was somewhere, looking for his brand clean pair of socks, Michelle and I were shoveling snow… yes, it seemed like we weren’t able to stop shoveling even after the traverse was over. Suddenly, Tony, the Byrd Camp supervisor, informed us that the pilots were going to perform our mission in the following half hour! This was excellent news.
The half hour gave us some time to drive 3 kilometers (1.86 miles) out of Byrd to dig out the first 18 core segments (each one of them about one meter, or 3.3 feet, in length) we had drilled three weeks before. Randy and I jumped on a snowmobile and headed there, while Michelle and Clement attached a sled to their snowmobiles to bring the cores to the plane, and joined us a few minutes later. We had to drive very slowly to make sure the cores didn’t get damaged during the ride.
Michelle and Clem arriving at the Byrd runway with the first core segments.
As I mentioned, the plane that was going to help us was a Twin Otter, which is smaller than the Basler that flew our cache with Lora the day after we started the traverse. Due to its smaller size, we would not be able to collect the 18 boxes and five fuel drums at the same time. We would have to fly first to three sites, fly back to WAIS station to deliver the cores (just on time for lunch!) and then fly to the three remaining sites, heading back to WAIS at around 4 PM.
Jessica, before taking off with the Twin Otter.
Using our site GPS location coordinates, it was extremely easy to find the orange fuel drums that marked the sites, and then locate the buried snow core boxes.
A view from the Twin Otter: The tiny orange dot is the fuel drum marking our site.
At each site, the pilot flew over the place one to four times before landing, to determine the best landing spot. That gave us a chance to enjoy our itinerary and former camps from above!
Our very straight snowmobile tracks seen from above.
Once on the ground, the plane taxied until it got right next to our cargo, which made it super easy to carry the core boxes and drums inside. Once the plane stopped, it was our turn to work. And by work I mean shoveling snow! By then, I was beginning to consider shoveling to be more of a hobby than work. We had to carefully dig out the snow core boxes and bring them and the fuel drum inside the plane as quick as possible. It was a great day, and I believe we were pretty efficient; it never took us more than 20 minutes between landing and take off.
View of the fuel drum, right next to the plane's door.
Because we were in an open field, the pilots had to taxi back and forth on its own tracks a couple of times, to compact and smooth the surface before taking off. Once the pilot and co-pilot were satisfied with the consistency of the snow beneath, they would push the accelerator.
During take off, the pilot and co-pilot jointly cranked the accelerator.
Between each site, we flew at low elevation (100 m). It was incredible to see some of our traverse legs from above, and even though we had encountered some pretty breezy days during the previous weeks, it was still possible to see our snowmobile tracks in some places.
After visiting three sites, it was time to fly back to WAIS Station. The plane was full, and heavy! This last take off seemed longer (much longer) than the previous ones… and definitively bumpier too.
After about 20 minutes in the air, we saw WAIS Station appear on the horizon.
WAIS Station on the horizon.
It was a strange feeling, to see a man-made structure appear in the middle of nowhere. It reminded me of the way I felt while, during the traverse, we were looking for our cache, and suddenly there it was, sitting in a great white vastness.
Five WAIS staff people were already on the ice waiting for us, or, more probably, they were waiting for the core boxes to bring them quickly into the freezer.
Our snow core boxes on their way to the freezer at WAIS Station.
After a good lunch at WAIS, we continued our ice core picking. By 4 PM, all cores were stored in the WAIS freezer. After then, the 2011 SEAT field work was truly completed. We had stayed safe, we hadn’t broken anything (or at least nothing vital than couldn’t be fixed), and we had had a fantastic life experience that will also help us better understand snow accumulation over West Antarctica!
Fair warning: Keep in mind that the ice cores still had a long way to go before reaching their final destination, the freezers at Bringham Young University!
Comments Off on Picking Up the Snow Cores from the Field
January 27th, 2012 by Maria-Jose Viñas
By Ludovic Brucker
The main objective of deep field traverses like ours is to make in-situ measurements and collect samples, which obviously cannot be done from air or space. So, during the 2010-11 and 2011-12 SEAT field seasons, we have been taking in-situ snow and radar measurements.
We typically had two different types of days during our traverse (both equally enjoyable!): traveling days, where we would move to a new site and set up camp, and days where we would collect snow measurements and drill a 20-meter deep snow core near our camp.
(Actually, we had a third type of day where we’d spend hours and hours shoveling during snow storms… but that’s a different story!)
The surroundings of our camp, with many choices for sites to dig our snow pit and drill our core. Notice the abundance of sastrugi!
My duties during the days we worked around our camp included digging a 2-meter deep snowpit and recording various measurements. When traveling on snowmobiles, or even while standing on the surface of the ice, one has no idea of what the snow lying beneath looks like. Amazingly, I often got a clear idea of the snow layering when burying anchors for setting up our tents. This provided a first quick overview of what it would look like the pit on the following morning.
Typically, my days started at 5:30 AM, when I would shovel snow in a cooking pot to get warm water for the rest of the crew, who were supposed to get ready in the following hour. The next step was to find the best place to dig the snowpit. Usually, a good place consisted of a uniform zone ranging several square meters and representative of the surrounding area. It also had to be free of sastrugi (small snow ridges created by the wind). Additionally, I had to take into account the sun’s position and how it was going to move across the sky in the following hours: it takes some time to dig the pit and collect measurements, and we absolutely didn’t want that the sun ended up warming the snowpit face where we’d be recording our measurements. Once I had decided on the location (usually a matter of seconds), I’d start digging.
After a good first hour of shoveling, I would have breakfast. Then I’d come back to excavate down to about 2 meters. The deeper the snow, the harder the layers got. I would usually shovel 6-7 cubic meters (211-247 cubic feet) of snow. The snow weighted about 300-400 kg (770-880 pounds) per cubic meter. I’ll let you do the math, so you understand that my colleagues’ help was always warmly welcomed!
The snowpit taking shape, and the equipment for firn-core drilling. The core will be drilled next to where the ruler lays on the ground. The blue tarp serves as wind protection for those working on the core. In the pit, it never gets breezy!
Once the pit was dug, I would try to smooth the snow surface as much as possible, covering an area wide enough to simultaneously record the following measurements:
1) Infrared photography
We put an infrared filter in front of the sensor of a standard reflex camera to record the snow cover stratigraphy (that is, the stacks of snow layers). This modification allowed us to take pictures at infrared wavelength (700-1100 nm), which is more sensitive to snow properties (such as grain size) than visible light is.
So, by simply taking a couple of photos, we were able to identify the various snow layers. We also used reference panels to calibrate our photographs and to get an idea of the vertical snow grain size variation with depth.
The modified infrared camera, inside the snow pit. We used foam panels to measure possible shadows and other artifacts that might influence the picture of the snow wall. We placed a shower tarp as a roof to ensure the pit wall was illuminated only by diffuse solar radiation.
Comparison between a picture taken with a conventional camera (top right) and an infrared picture of the snow face (in pink). The infrared photo shows many more details of how the snow varies its properties vertically.
2) Visual stratigraphy
After taking infrared pictures, I would visually identify the snow layering simply by looking at the snow wall. Each time I saw a change in grain size, snow structure, and so on, I would mark a new layer. This process is less accurate than using infrared pictures, because it can be visually challenging to identify smooth vertical variations from one layer to another. However, I’d normally be able to distinguish the main features. I would then take snow grain size and hardness measurements for each visually identified layer.
Me, using a graduated magnifier to measure snow grain size.
3) Snow temperature
We measured snow temperature at every 10-cm interval, from the surface to the bottom of the pit. Most of the time, surface temperatures were about -10oC (14oF), and the lowest temperatures (found 2 meters below the surface) ranged between -25 and -29oC (-13 and 20oF).
4) Thermal conductivity
Thermal conductivity values tell us about how efficiently heat propagates through the snow cover. This way we can understand how quickly air temperature variations can travel down the snow. Estimating heat transfer through the snow cover is important in modeling the energy exchange between the snow and the atmosphere, among other characteristics.
We made our measurements using three needle probes: the one in the center continuously measures snow temperature, while the two on the sides slightly warm the snow surrounding them. The idea is to measure how fast and with which intensity the heat wave reaches the temperature-recording needle.
5) Snow density
Another important characteristic of snow is its density, or mass for a given volume. We made those measurements at two vertical resolutions (2 and 10 cm) using density cutters (thin metalic shapes that I inserted in the snow wall to extract samples). I did know that hard snow layers exist in Antarctica, but I was surprised to find out how difficult it was to insert a thin sharp metal piece into these layers! We bagged and preserved the 2-cm-thick samples (they will be shipped to the BYU lab in Utah for further analysis) and we weighted the 10-cm-thick samples directly in the pit.
Me, holding a 2-cm-thick sample. It will be bagged and shipped to the U.S. by the end of the Antarctic summer season.
Our route went across the West Antarctic Ice Divide, a topographic feature formed by a large-scale weather system (an atmospheric depression that comes from the ocean and creates snow storms inland).
We traveled across this divide, which presents very different snow accumulation scenarios on each of its sides. On Byrd’s side, where we started and ended the traverse, snow accumulation is low. But on the other side of the divide, there’s more snow accumulating each year.
Each camp we worked at presented different snowpacks, though they shared specific distinguishable layers at given depths. For instance, there was a layer with large snow grains at 0.92 m depth – this layer was visible throughout hundreds of kilometers.
In summary, during the 2011 SEAT traverse, we dug seven snowpits and collected all the above measurements down to 2 m deep. Now, it’s time to get in front of the computer to analyze and understand these incredible data sets!
January 24th, 2012 by Maria-Jose Viñas
By Michelle Koutnik
This is one of our six camping sites. The Scott tent is the big yellow tent and the others are the sleeping tents. The bathroom is at the end of the site.
Each of our six different camping sites consisted of one cook tent, four sleeping tents, and a bathroom area (more on that later). The cook tent was a “Scott” tent, which is an enduring style and named for the polar explorer Robert Scott. It was a tight space for five people but we were able to crawl in and then sit around together with one person managing the two-burner propane stove in the corner. The Scott style tent was much sturdier than our mountain-style sleeping tents, but it was also more time consuming to put up and heavier to transport. Since we were moving nearly every other day, we wanted to keep our camp as simple and as light as possible. The Scott tent was a necessary addition for cooking, but also as a reliable shelter in the two strong storms we experienced during the traverse.
Camp with our snow machines and the radar sled.
It took a few hours to set up camp, and a similar amount of time to break it down and repack the gear on the sleds. Randy, Jessica, and I were responsible for breaking down most of the camp and for setting up some of the camp on our own while Clement and Ludo collected radar data on traverse days. Once camp was set up at a new site, we could start melting snow for water and start cooking dinner.
On a traverse day, our camp life included the take down and setup of camp, plus collecting radar data. On an ice-coring day, our camp life included digging and sampling the snow pit, drilling the ice core, and eating a hot lunch. We ate well out there! Our standard meal plan included tortellini with pesto, spaghetti with meatballs, sausage with rice and vegetables, and burritos. Sausages were popular and made their way into many meals. Special nights featured hamburgers with tater tots, and on Christmas we cooked scallops with rice and vegetables. Hot lunch on ice-coring days featured cheesy bagels fried with butter in our cast-iron pan. Since all the cheese and bread was always frozen, it required frying it all together before we could eat it – but it tasted great this way! Stormy-day food was simplified but did afford us the time to enjoy pancakes (two storms, two pancake breakfasts).
Frying cheese and bagels in butter for lunch.
The storms also affected our standard bathroom situation – usually a snow pit and tarp configuration. Ludo took the high winds and blowing snow as a challenge and created a snow-brick bathroom, which we tried our hardest to maintain from drifts!
Snow-brick bathroom and camp after a storm.
Maintaining camp and completing the science goals was a big job but we enjoyed being out on the ice sheet. For example, Christmas was a wonderful day to share together because a big storm started to clear, and we had lovely gifts to exchange, two small Christmas trees, and a very nice meal. Overall, the camp life was comfortable and enjoyable and with such a hard-working team, we were efficient at all the tasks necessary to make the camp run and be successful with the science.
Traversing to a new camp site.
January 23rd, 2012 by Maria-Jose Viñas
By Clement Miege
Hi there! After more than three weeks spent in the field, our team is very happy to be finally back, with many memories of the traverse. This year has been a very intense experience and I would like to tell you a little more about this expedition. I will focus on the days we were doing radar surveys. Indeed, two different studies were set up during this field work. The first one was during the traverse days, where we did a radar survey from one camp to another with a range of 50-90 kilometers (31-56 miles) between the camps. On the other days the surveys were smaller, set up around each camp; they consisted of a 10-km bowtie and a 280- by 280-meter (918- by 918-ft) grid to get a better idea of the spatial variability of snow layer depth surrounding each core site. These grid surveys will show us how representative the ice core is compared to the surrounding area and help answer the question of whether we would have gotten a different result if we had drilled our ice core a few paces this way or a few paces that way. We were also looking more in detail at the layering in a 2-meter (6.56-ft) snow pit; to do that, we were using a metal plate at different depths of the snow pit.
The radar is sitting on a triangle-shape sled that is pulled by a snowmobile.
Here is a picture showing the two radars that operated simultaneously on the sled:
Both radars looked at the first 20 meters of the snow pack, sending electromagnetic waves into the snow. The snow radar (the big green horns in the picture) operates in a frequency range of 2-8 GHz. The other radar (the smaller brown horns) is the ku-band radar, sweeping between 12 to 18 GHz. The lower the frequency, the deeper the radars look. We have both radars for some redundancy in the system, imaging the snow/firn closest to the surface, which we core twice, and then the snow radar peers deeper than the cores to provide literally a deeper look. In addition to the 2 radars, we needed to know the elevation we were at, which is important for comparison with airborne data and also for modeling precipitation and temperatures. For that, we simultaneously collected GPS coordinates, which gave us our exact latitude, longitude and elevation every 5 seconds. The GPS antenna was on the very top of the sled, about 2.5 meters (8.2 feet) high.
On this sled, beside the radars sitting in the red box, we had packed: a blue bag, two black duffel bags and an orange bag. The blue bag was a survival bag, with all the gear needed in case we would have been caught in a storm; it included a tent, a stove, a shovel, and some food. The two black bags contained Ludo’s and my sleep kits, and the orange bag had some extra food, in case we were stuck for couple days. For the snow mobile, we had a repair kit under the seat to troubleshoot a possible failure. We were carrying two extra cans of gas as well. With this set-up, we were able to get a pretty light sled that was still comfortable and had all the gear we’d need in case of a storm or other circumstance separated us from the rest of the team, who were carrying all the camp gear. Fortunately, this never happened!
But now, let’s go back to the survey. The travelling days were the ones where the team was the most vulnerable: while we were traveling we had no shelters or camp set up to get back to if anything went wrong because we had to break down the entire camp in the morning, pack all gear on the sleds and ride with the snowmobiles pulling the sleds to the next camp. After driving between 50-90 km (31-56 mi), we would build our new camp, usually that same day in the afternoon. We had a total of seven travel days, covering a distance of about 500 km (310 mi).
Our sleds at camp. Strapping all your gear on the sled takes time and requires inventive skills; we called this the art of “Strapology”!
During travel days, the radar team left camp first, mostly because we had to drive at low speed to ensure the radar’s safety. Indeed, on the days we ran into large sastrugi (small ridges of hard snow), we drove at less than 10 km/h (6.2 mph). These sastrugi made our travel a little bit more difficult. Toward the end of the day, the team responsible for breaking down camp would leave the radar team and go 20 km (12 mi) ahead, to start setting up the new camp.
The days we were at camp, we did some small radar surveys: a bowtie and a grid around the core site. To help us drive the snowmobile straight for the grids, we set up flags to visualize the corners and sides. In the deep field, everything is white and flat, so it is hard to maintain a nice bearing just by following the GPS for such a small grid.
Clem and Michelle, getting ready for a short walk to set up the grid flags.
The last side survey with the radar was done in the snow pit. After analyzing the snow pit and picking up snow samples for further laboratory analysis, we used the pit to calibrate the radars and look at a detailed snow layering for the top 2 meters.
Ludo in the snow pit, sliding a metal plate in the snow at different depths. The plate creates a very bright horizon that is easily detectable on the radar return signal.
After a day of travel or after doing a grid, it is important to back up the radar data. The sleeping tents are a warm and cozy shelter to set up a “recharging station”. In addition to backing up the radar data, we recharged the satellite phone, GPS, and computer batteries.
We had to check the integrity of the radar sled at each camp site. Here is Ludo, checking the screws on one of the three legs connecting the snowboard to the sled.
To conclude, I want to say that this traverse was definitely an amazing experience and I was happy to share such a good time with the team. I am already excited to start looking at the radar data in detail to see what we can learn of the past few decades of snow accumulation in this part of the West Antarctic Ice Sheet.