Student Project: Glacier Mass Balance

2015 JIRP Student Project: Glacier Mass Balance

Faculty experts: Matt Beedle, Lindsey Nicholson, Shad O’Neel.

Overview: The glacier mass balance project works to directly measure the gains and losses of snow and ice across the surface of Taku and Lemon Creek glaciers. These measurements will be added to and placed in the context of the 50+ year continuous record of mass balance on the Juneau Icefield. The goal of this project is to quantify snow accumulation and ice melt for balance year 2015.

Level 1 students are not expected to continue their work beyond the summer field camp unless computations and write up are not completed during summer.

Level 2 students should expect to continue to work on data analysis beyond the summer season, with a more detailed analysis and report turned in near the end of fall semester.

A.    Snow accumulation. Snowpits will be excavated at several (15-25) established locations on Taku and Lemon Creek glaciers to the depth of the previous summer surface. In each pit a density profile will be computed and plotted with a provided template. Column average density and snow water equivalent are calculated. Levels 1&2.

B.     Snow and ice ablation. Stake measurements will be measured as possible (3 sites at minimum). These measurements will be used to calculate snow and ice melt. Levels 1&2.

C.     Firn evolution. At snowpits near the ELA, continue excavation through 2014 firn. Compare and contrast SWE with 2014 observations. Level 2.

D.    Glacier-wide balance. Students will learn to construct a balance profile from the point-data and then estimate the glacier-wide balance using a supplied glacier geometry. Levels 1&2. Level 2 students will use a degree-day model (supplied) to adjust all measurements to a common date (may involve synthetic wx data) and compare estimates over the original and present-day surfaces to compare and contrast 2 common analysis frameworks (conventional vs. reference-surface balance).

E.     Cumulative balance. Using the entire measurement time series, students will calculate the cumulative mass balance as a function of time and display this work graphically. They will discuss the similarities and differences between the two glaciers response to similar climate forcing. Levels 1 & 2.

F.     Climate forcing. Quantify the relationship between temperature and mass balance, as well as precipitation and mass balance. This exercise is for Level 2 students upon return from the icefield.

Timeline and logistics: snowpit excavation occurs on a semi-regular basis throughout the traverse, with 2-3 days/week spent in the field.  This is a labor-intensive project. The mass balance team generally transports themselves to snow pit locations via human power.  Logistics are limited for this project, but the project members will travel to places where most students will not. Students should expect at least 1 day per week in camp working on data analysis. New data will be collected, processed and preliminary interpretations made. Additionally, student reports will need to include external (supplied) data sets such as Area Altitude Distributions, and historic mass balance values.

References (numbered by priority, i.e. study #1 first, #10 last):

1. Pelto, M., Kavanaugh, J., and McNeil, C., 2013, Juneau Icefield Mass Balance Program 1946–2011: Earth System Science Data, v. 5, no. 2, p. 319–330.

2. Arendt, A.A., Echelmeyer, K.A., Harrison, W.D., Lingle, C.S., and Valentine, V.B., 2002, Rapid Wastage of Alaska Glaciers and Their Contribution to Rising Sea Level: Science, v. 297, no. 5580, p. 382–386.

3. Gardner, A.S., Moholdt, G., Cogley, J.G., Wouters, B., Arendt, A.A., Wahr, J., Berthier, E., Hock, R., Pfeffer, W.T., Kaser, G., Ligtenberg, S.R.M., Bolch, T., Sharp, M.J., Hagen, J.O., and others, 2013, A Reconciled Estimate of Glacier Contributions to Sea Level Rise: 2003 to 2009: Science, v. 340, no. 6134, p. 852–857.

4. Cogley, J., Hock, R., Rasmussen, L., Arendt, A., Bauder, A., Braithwaite, R., Jansson, P., Kaser, G., Möller, M., Nicholson, L., and others, 2011, Glossary of glacier mass balance and related terms, IHP-VII technical documents in hydrology No. 86, IACS Contribution No. 2: UNESCO-IHP, Paris.

5. Owen, L.A., Thackray, G., Anderson, R.S., Briner, J., Kaufman, D., Roe, G., Pfeffer, W., and Yi, C., 2009, Integrated research on mountain glaciers: Current status, priorities and future prospects: Geomorphology, v. 103, no. 2, p. 158–171.

6. Criscitiello, A.S., Kelly, M.A., and Tremblay, B., 2010, The Response of Taku and Lemon Creek Glaciers to Climate: Arctic, Antarctic, and Alpine Research, v. 42, no. 1, p. 34–44.

7. Larsen, C.F., Motyka, R.J., Arendt, A.A., Echelmeyer, K.A., and Geissler, P.E., 2007, Glacier changes in southeast Alaska and northwest British Columbia and contribution to sea level rise: Journal of Geophysical Research: Earth Surface, v. 112, no. F1.

8. O’Neel, S., Hood, E., Arendt, A., and Sass, L., 2014, Assessing streamflow sensitivity to variations in glacier mass balance: Climatic Change, v. 123, no. 2, p. 1–13.

9. Huss, M., Hock, R., Bauder, A., and Funk, M., 2012, Conventional versus reference-surface mass balance: Journal of Glaciology, v. 58, no. 208, p. 278–286.

The Blister

By Justyna Dudek

At Camp 10 there were many different ways to spend free time: enjoy the great views from the deck, read, work on science project proposals, cook and eat food… or you could take a field trip exploring what we usually spent considerable effort avoiding: the inside of a giant crevasse! (Note 1: Dear parents reading this blog, please do not worry; this was a completely controlled undertaking, supervised by our outstanding and experienced safety staff. Note 2: Kids, don’t try this at home.) Finally we got to use the great outdoor skills we learned in the safety course of Camp 17 by rappelling into a crevasse associated with a feature called “The Blister”.

The Blister as seen from the side of 'Taku B'.  The Blister is in 'North Basin' just north of Camp 10.  Water accumulates here during each melt season.  Photo by Justyna Dudek

Why would someone want to lower themselves into a giant, water-filled ice crack? For one, it is a great way to see the annual accumulation of snowfall.   Annual layers of accumulation are exposed in the crevasse, without having to dig a giant snow pit. Secondly (and most of all), it is really great fun.

[NOTE:  Click on any of the images below to open a slideshow with all photos and captions.]