MELTING ICE PATTERNS AND TOPOGRAPHICAL CHANGES ASSOCIATED WITH DIFFERENT SURFACE COVERS AT THE TERMINUS OF THE MATANUSKA GLACIER, AK

The surfaces of glaciers are constantly changing due to different melting processes. To quantify the topographic changes from melting, we looked at three adjacent surfaces with different debris cover. Debris cover has often been attributed to increasing or slowing melt rates. The melting of glacier ice depends, in part, on debris cover of the ice. For this exercise we chose to determine melting processes at the terminus of the Matanuska Glacier, a popular tourist destination in Alaska.

The first area was a control surface located in an area with clean ice that was crevassed near the margin of the glacier. The second area was located in an area where the ice had a thick layer of sediment deposited on top. The third area was located where the ice had a thin layer of sediment deposited on top. Each area was documented at two separate times ranging from 4 to 6 weeks apart between June 23, 2019 and August 16, 2019. Drone footage captured the images and digital elevation models (DEMs) were processed using structure from motion techniques. The DEMs provide the basis for shape metrics such as roughness (the difference I height from adjacent points), slope (steepness), and aspect (orientation measured from 0 to 360 degrees).

For the debris-free and debris-thin area, the predominant orientations are controlled by the crevasse patterns in these areas. In the debris-thick area, there is a shift from a random orientation to a southwest sloping orientation. The debris-free area also shows that the peak of roughness shifted slightly rougher values. In contrast, the debris-thin peak shifted more to higher roughness values, and the debris-thick area shifted to even rougher values. In the debris-free area, the ice shifted to slightly less steep values. In the debris-thin area, the ice shifted to slightly steeper values. In the debris-thick area, the ice shifted to much steeper values. Collectively, these observations indicate the debris cover extenuates the melting over the summer period and was not thick enough to stop melting from occurring. These changing surface reflect the melting ice patterns removing the glacier mass.