Unit 2: Glacier Mass Balance, Albedo, and Surface Melt

Alia Khan (Western Washington University)
Twila Moon (University of Colorado, Boulder)
Spruce Schoenemann (University of Montana Western)

Summary

Glacier Mass Balance, Albedo, and Surface Melt

Now familiar with the glacier basin system, Unit 2 takes students to the ice sheet and explores the seasonal changes to the glacier surface and how these play into the gain or loss of glacier ice mass. Students examine the seasonal snow cover and the changing character of the ice sheet surface. This includes beginning to understand where and when surface melt forms on the top of the ice sheet and how the ice sheet surface character influences the surface albedo, or reflectivity. Learning is supported through activities with surface property images, real online interactive science data, and GIS data that allow for independent discovery.

Used this activity? Share your experiences and modifications

Learning Goals

Driving Question: What processes are occurring at the glacier surface?

Learning Goals: 1) Describe the processes that shape the components of the glacier surface. 2) Recognize what the glacier surface system looks like in different seasons.

Context for Use

The content in Unit 2 is appropriate for upper-division geology, environmental sciences, meteorology, and other geoscience courses; junior/senior-level courses in which geomorphology, climatology, or glacial geology studies are building on prior introductory material. Unit 2 activities can easily be adapted to serve small- or large-enrollment classes and can be executed in lecture and lab settings as an interactive lecture activity, an in-class activity in which students work in small groups, a short lab exercise, or as part of a ~three-week investigation incorporating GIS and Interactive Environments to understand a glacier basin system and cryosphere using the entire "Exploring the Glacier Basin System" module. This is the second unit in the module and examines the seasonal surface changes of the glacier basin system, including surface melt and albedo (reflectivity). This unit also introduces the concepts of glacier length fluctuations in response to changing mass balance.

Unit 2 also introduces GIS student exercises. These exercises use the free QGIS and QGreenland software for students to explore authentic scientific data in a real GIS analysis environment. These exercises work well in a computer lab or where students can use individual or shared computers, ideally with QGIS software already installed and QGreenland already downloaded to the computer.

Description and Teaching Materials

Part 1:

In this lesson students are beginning to learn about and explore the seasonal changes in the glacier basin system, focusing on the glacier surface. The image slide deck provides image comparisons for the glacier surface properties across the annual seasons. Instructors can use the image slide deck and have students respond to Think-Pair-Share prompts via Clickr (or comparable app like TopHat) while students engage in think-pair-share discussions around the questions.

Think-Pair-Share Prompts

  1. Which three-month category most closely relates to peak snow accumulation? And peak glacier melt? DJF, MAM, JJA, or SON?
  2. How does the reflectivity of the ice sheet change from January to December?
  3. What are some positive feedback loops (think processes) that might be occurring on the surface of the ice sheet?

Part 2:

Work with NSIDC Greenland Melt Map and albedo data. Have students develop their own albedo data plots based on the raw data, to visualize the seasonal evolution in surface melt in 3 key regions (divide, transition/ELA, margin). Also, discuss the equilibrium line altitude (ELA), glacier mass balance, and weather (temperature, precipitation). (Complementary graphs from spreadsheet data; Greenland Today reports; paired with Landsat imagery from similar time).

Part 2 exercises use the QGreenland QGIS environment. Follow these instructions to install these tools: Mod 1 GIS Setup Instructions.pdf (Acrobat (PDF) 2.3MB Dec8 21)

Part 3:

In Part 3 students will be introduced to the concept of natural glacier length fluctuations due to glacier mass balance variations. The instructor will present the Image Slide Deck introducing examples of modern glacier length variation and discuss how the terminus position varies over different timescales based on annual mass balance variations and thickness of the glacier.

What we learned:

  • Students understand the annual cycle of glacier ice mass gain and mass loss, and how this influences the glacier surface.
  • Students know what albedo means and how and when it changes on the glacier surface.

Teaching Notes and Tips

GIS and QGreenland

The GIS activities in this module use QGIS and QGreenland. Use the information in this file to assist with setup: Mod 1 GIS Setup Instructions.pdf (Acrobat (PDF) 2.3MB Dec8 21). The QGIS software is a free alternative to the ArcGIS software and has similar capabilities. QGreenland is a QGIS project environment that provides a collection of Greenland-focused data. The QGreenland Download webpage has information on installing QGIS and using QGreenland. QGreenland provides a full User Guide and also online tutorial and how to content that can help you to learn about using QGIS and QGreenland for the very first time.

This video PolarPASS Mod 1 Unit 2 teacher guide video.mp4 (MP4 Video 31.4MB Jan21 22) provides a short on-screen demonstration of adding the Glacier Basin Data to the QGreenland environment.

Note that QGreenland includes a Glaciology dataset with annual glacier terminus positions for marine-terminating glaciers. This could be an interesting dataset to explore, but discussion would have to include understanding differences between land-terminating and marine-terminating glacier environments. Students will also explore glacier terminus change in Module 2: Long-term Spatial Transformations of the Glacier Basin System.

Working with Data

Datasets within PolarPASS are primarily provided as Excel spreadsheets. Note that instructors could also copy these data to other formats or instruct students to use alternative software for working with the data. For example, exporting the data to .csv files, working with data in R, or working with data in Python. For those who would like to work in Excel, but are not familiar with the software, here are basic instructions on plotting. This video also provide more information on plot formatting.

Assessment

Assessment: Mod 1 Unit 2 Assessment.docx (Microsoft Word 2007 (.docx) 1.3MB Aug18 22)

Annotated imagery: Students annotate satellite imagery of the Kangerlussuaq glacier system to identify surface components present during the summer and winter seasons.

Annotated block diagrams: Students annotate generalized block diagrams of the Kangerlussauq glacier to depict the connections between surface components and processes that occur within the glacier system during the summer and winter. The annotated diagrams will show how one change in the system affects other parts of the system.

References and Resources

Source for Greenland albedo data: Multilayer Greenland Ice Surface Temperature, Surface Albedo, and Water Vapor from MODIS, Version 1

Leclercq, P. W., A. Weidick, F. Paul, T. Bolch, M. Citterio, and J. Oerlemans (2012), Brief communication "Historical glacier length changes in West Greenland," The Cryosphere, 6, 1339–1343, doi:10.5194/tc-6-1339-2012.

Roe, G. What do glaciers tell us about climate variability and climate change? Journal of Glaciology (2011).