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SEAT: Satellite Era Accumulation Traverse: Ice cores: From Antarctica to the lab

November 4th, 2011 by Maria-Jose Viñas

By Lora Koenig

Two weeks ago, I traveled to Utah to help the team finalize planning for this season and to visit the ice core lab and our 2010 ice cores at BYU. The entire was there, except for Ludo, who was in Hawaii competing in a triathlon. (Ludo is not only a top scientist but a top triathlete. I hope he is not getting too use to the warm weather because in less than a month he will be facing temperatures around 0°F.)

There were a few tasks to complete in Utah. The first was to look at many different types of satellite data on the region where we will be traveling to make sure there aren’t any crevasses or other dangers along the route. A crevasse is a crack in the ice. As the ice flows (yes, ice flows just like a mound of putty), it can crack when it goes over a bump or accelerates. Here is a recent picture of crevasses in Western Antarctica, from a NASA Operation IceBridge flight.

Photo Credit: Michael Studinger/NASA

As you can imagine, we would not want to drive a snowmobile in an area like this. So we spent hours looking over maps of the rock bed under the ice sheet to look for bumps, visible and radar satellite images of the surface of the ice sheet, and satellite data showing the velocity of ice flow to make sure that we are traveling on the safest possible route. We ended up moving one ice core drilling location slightly to avoid a dark spot that we could not clearly identify in one of the radar images, just to be extra cautious. Once the route was established, we generated waypoints (coordinates) every kilometer to load into the GPS units that we will use for navigation. The place we are going to is big, white and flat: It is very easy to lose your sense of direction, so we rely heavily on GPS units for navigation.

For some great images and videos on how ice flows in Antarctica please check out this video, made by our NASA colleague Eric Rignot who (thanks again, Eric!) also checked the data that sits behind these videos to help ensure our safe route.

If you would like an in-depth look, this file, which opens on Google Earth, shows our final route with points every 1 km.

Our second task in Utah was to visit last year’s ice cores and have our first meeting to discuss the initial data coming from them. First, here is a picture of a core in the field, taken in December 2010.

In this photo, Michelle (right) is labeling the core and I (left) am getting the core tube ready for storage. The arrow on the ice core bag shows which direction is up.  It is very important that all the cores are labeled in order, or we would lose our time series. The metallic tube in the center left of the picture protects the core during shipping. The core in the tube gets placed in the white core box sitting open on the left side of the picture. (Also, notice that Michelle is standing on a bright green pad to help insulate her feet from the cold snow. It’s a veteran trick for keeping your toes warm.)

Here is that same core in the lab today.

Summer is holding what was about 8 feet of the core and the rest of the about 50 feet of core is stacked in the boxes behind her, waiting for analysis.

Here is a very basic explanation of what happens to the cores once they arrive at Summer’s lab at BYU. (Normally, Summer would be the one writing this, but she is currently studying glaciers in Bhutan.)

When the core arrives, we put it in the freezer.  Here is Landon peering out of the freezer door:

In the freezer, we weigh the core to determine its density and measure its electrical conductivity, which tells us about its chemical composition. A volcanic event would be detected in the cores by the electrical conductivity and can be used to set a point in time. We take all these measurements twice, or even three times, to make sure they are accurate.

Here is a picture of a core that Landon is preparing, sitting on the freezer’s core handling tray:

This freezer is set to -4°F, so when not posing for a picture, Landon would normally be in a parka with gloves on.  As you can see, the core is still in its protective bag, which will be removed when actually processing the core. From here, the core is cut up into sections less than an inch (2 cm) long, and melted for the next stage of analysis.

I will add a quick note here that on last year’s traverse Landon was our lead driller. Both Landon and Jessica are masters students at BYU. They are not only integral players of the field teams, but are also the lead students for the lab analysis of these cores.

Once we have melted the core and put it in a bottle, we send it over to Jessica.

Here is Jessica operating the mass spectrometer (black box to the left in the picture with the blue screen) that will measure the stable water isotopes used to date the core. The isotopes in the snow have an annual cycle and it is this cycle that determines age of the core.  An isotope is an atom, in our case an oxygen atom, that has different variations with different number of neutrons and atomic numbers.  Oxygen has three stable isotopes: 16O, 17O, and 18O.  The peaks and valleys in the ratios of 18O/16O reflect the warmer (summer) and cooler (winter) temperatures, respectively.   Once the mass spectrometer determines the number of isotopes, we can establish the age of the core, in a way similar to counting tree rings. During this process, the core is in the little blue vials just to the right of Jessica.

After spending some time in the lab, we looked at the data from the first core that has been analyzed.  At this point the density and isotopes have been measured and Summer is carefully working to put together the depth-age scale, which is the age of the core at each depth where the core use to sit in the ice sheet.  I will use the density data from the core to determine an age-depth scale from the layers in the radar data and if all goes well the radar and ice core will line up giving us confidence in our analysis.

Last Monday, when I returned to Goddard, I had received my travel itinerary.  We will be leaving the U.S. on Nov 17th to make our journey down to Antarctica.  With all of this preparation, I am eagerly awaiting getting my feet on the Ice.

SEAT: Satellite Era Accumulation Traverse: When Canada Stands In for Antarctica

October 21st, 2011 by Patrick Lynch

By Summer Ruper

Hello SEAT blog followers. I am Summer Ruper, and I would like to share with you a little bit of the ice coring adventure that begins well before the field team heads to Antarctica. Before we start drilling ice cores in the harsh cold and wind of Antarctica, we have to train our field team on the drill and sampling procedures. To do this, we took a trip to a slightly warmer region with ice: Athabasca Glacier in the Columbia Ice Field. Athabasca Glacier is near the Canadian town of Banff, and is one of the most visited glaciers in the world. It’s a beautiful area, and plenty of ice to play with.

To begin, we must first answer the question: What is an ice core? Simply put, it is a core sample collected from a glacier or ice sheet. But the ice core is not entirely made up of ice; with the snow fall and wind also come dust, salts, and even ash from volcanic eruptions. All of this is contained in the ice cores and provides information about how snowfall, temperature, and winds have changed over time. A lot of important information is buried in the ice and snow on glaciers and ice sheets, but you have to get the ice out in order to get at that information.

Piece of ice with bubbles inside. These bubbles provide information on the composition of the atmosphere at the time they were trapped in the ice.

Piece of ice with bubbles inside. These bubbles provide information on the composition of the atmosphere at the time they were trapped in the ice.

In order to collect the ice cores, we use a specially designed ice core drill. The one we use is called the FELICS, and is designed and manufactured by Felix and Dieter Stampfli in Switzerland. Basically, the drill has a sharp ring on the end that cuts the ice and feeds the core into a one-meter long barrel. We pull the one-meter section up, empty it out of the barrel, and then drill another one-meter ice core from the bottom of the hole. We do this over and over again until we have drilled to a depth of about 20 meters, and have about 20 one-meter long ice cores.

Randy Skinner, Jessica Williams, and BYU students drilling an ice core on Athabasca Glacier.

Randy Skinner, Jessica Williams, and BYU students drilling an ice core on Athabasca Glacier.

On Athabasca Glacier, our field crew learned how to operate the drill, handle the ice cores, and generally deal with problems that might arise. We were also able to show the tourists visiting that glacier how the drill worked, let them see (and taste) the ice, and share a little of our knowledge and excitement about glaciers and the environmental records contained in the ice. We had a lot of fun, and Jessica and Randy are excited to transfer this experience to our work on the Antarctic ice sheet soon.

Summer Rupper showing an ice core to group of tourists on Athabasca Glacier.

Randy Skinner “sharing” an ice core with a budding glaciologist.

In another post, we will show you what we do with the ice cores once they return to the lab and share some of our preliminary results from last year’s ice cores.

Jessica Williams, Randy Skinner, and Summer Rupper look for the “perfect” spot to drill a core.

Jessica Williams, Randy Skinner, and Summer Rupper look for the “perfect” spot to drill a core.