A Reconnaissance Mission with GPS Receivers

By Brooke Stamper

With safety training and ski practice behind us at Camp-17, we have begun to “hit it hard” as M. M. Miller would put it. Our daily routines have transitioned from gearing up to be outside and gathering our “glacier legs”, to spending time inside working on our research  projects.  The opportunities for place-based education are endless on the icefield and many students are taking advantage of the resources provided. I recently took advantage of an opportunity to set up GPS satellite receivers with Jason Amundson, Assistant Professor of Geophysics at the University of Alaska Southeast.

Jason and I rode on a snow machine and towed “the coffin”, a storage container with the bulky equipment in it. We traveled seven miles down glacier to a predetermined transect and placed our first of four satellite receivers just below the equilibrium line altitude, where the annual average snow accumulation and ablation are equal. We placed an additional three receivers at equal distances upglacier until we were at the convergence of the Matthes Glacier and Taku Glacier.  The GPS receivers will continuously track the velocity of the glacier over a one-week period to determine what portions of the glacier respond most strongly to meltwater input, and to what degree.  The project is simply exploratory at this stage.  Our hypothesis is that the daily variation in glacier velocity will be higher in the ablation area rather than on the “high ice” in the accumulation area.

The historical and current GPS data collection has been at specific points on the icefield to gather long-term annual data on surface elevation and velocity.  Most notably, Scott McGee and Ben Slavin set up stakes at set locations along a line that runs across the Taku Glacier from JIRP’s Cook Shack to Shoehorn Peak as well as a second set of stakes directly parallel to those stakes but starting from our favorite outhouse, curiously named “Dream Land”. On these stakes are placed black trash bags to allow us to better see the daily flow of Taku Glacier.  Eventually, the stakes will begin to arc and there will be noticeable change in location of the stakes. This will give us a fantastic example of strain on the icefield and an explanation as to why there are more crevasses on the edges of glaciers as compared to the center. Because the margins of the glacier are influenced by friction, the differences in flow rates are greater; therefore, there are more crevasses we must mind when downhill skiing from the Nunatak that Camp-10 sits on.

Although all of the students have begun to work independently on our projects, we are all aware that our efforts, in total, are for the betterment of the knowledge and understanding of the Juneau Icefield. Together as classmates and expedition-mates we are all here for the furthering of science on glacial dynamics and how this specific environment fits into the greater Earth system.

Links

The Crevasse Zone:  GPS Glacier Surveying on the Juneau Icefield, Alaska - Scott McGee's great website devoted to JIRP surveying efforts.

Surveying the Taku Glacier

By Stephanie Streich

This week, I had the opportunity to take part in two different glacial surveys to better understand the nature and changing characteristics of the Taku Glacier, located in the backyard of Camp-10.

The first surveying activity was the monitoring of the surface elevation of Taku Glacier, to track its pattern of growth and deflation. The monitoring of this part of the icefield has been one of JIRP’s long-running projects, and has contributed to a thorough record of this section of the ice.  On this occasion, German surveyor Christian Hein and I traveled by snow machine across Taku Glacier to the same locations that are measured every year with a global positioning system (GPS). Upon reaching the approximate location of each waypoint, while carrying the GPS receiver, antenna and data logger, I walked around the snow machine to find the exact coordinates of the waypoints. Once the points were found, an elevation could be determined by holding the GPS antenna a fixed distance above the ground. This continued throughout the day until all the data for the waypoints were collected (approximately 40). Not only did I learn about the techniques used in the surveying, I was able to appreciate the tedious process of maintaining a record of the health of a glacier. On another note, I was surrounded by a gorgeous landscape that I do not have the privilege of seeing in my every day life, at the University of Alberta.

On my second day of surveying, I went out on the icefield with my former University of Alberta professor, Jeff Kavanaugh, and University of Alaska Southeast professor Jason Amundson to undertake the fieldwork required to monitor the movement of an area of glacial ice on the Taku. During this time, we set up a grid of predetermined GPS coordinates with nine wooden stakes that were jammed into the snow. Once the grid was established, a GPS  antenna was placed on each of the stakes for a half hour to procure their exact locations. The height of the poles were also measured to monitor the rates of snow ablation, or melt.  Jeff intends to revisit these sites two more times before we leave Camp 10 to obtain their GPS coordinates to eventually calculate the surface velocities of the moving ice.

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Stephanie Streich by a GPS antenna, mounted to one of the strain gauge stakes. Photo by Jeff Kavanaugh.

As a student that had not done much field work in the past, participating in JIRP has made me appreciate working in the field in a way that I did not value in school. In a university setting, I learned about field work through the presentations from my professors and in my labs. However, learning about fieldwork and actually applying it in real life are two different things. For example, the presentations that Jeff delivered in class did not come near to actually experiencing what he does as a professional.  In class, field work felt like a strict, rigid, process, which  can be attributed to the stressful environment of university academia. Instead, I was pleasantly surprised to find out  through experience that the work I was doing with Jeff was fun, insightful, relaxed and made me want to know the results of our tests. This is a message that I want to stress: that without participating in JIRP, I may never have known that science does not have to be a rigorous, structured activity in a stressful academic environment. I had lots of fun during my two field trips and hope to do more as the program continues into August.