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Sky selfie

from part of NSIDC’s Greenland-today 20 August, 2014 post…

Sky selfie

Our colleague Jason Box of the Geological Survey of Denmark and Greenland (GEUS), and graduate student Johnny Ryan of Aberystwyth University spent much of the summer on the western ice sheet at Camp Dark Snow, near Kangerlugssuaq on the Arctic Circle (67 degrees north latitude at 1,010 meters above sea level). The team was investigating the Greenland surface albedo, climate, and surface melting, and how these evolve during summer. As part of the research, they have been using drones (Unmanned Aerial Vehicles, or UAVs) to photograph the surface from low altitude to examine the development of surface structures associated with melting. Strips of images and albedo measurements from the UAV are compared with simultaneous satellite images from the NASA MODIS sensor as an intermediate state to relate ground albedo measurements with that of the entire ice sheet. UAV photos reveal a surface riven with fractures, and drained by ephemeral rivers of melt water. The mid-summer melt surface in this area is pocked with 0.5 to 1 meter-wide (1.5 to 3 feet-wide) potholes with black grit and dust collected at the bottom. This black material is called cryoconite, and is comprised of dust and soot deposited on the surface, and melted out from the older ice exposed by melting. The dark patches are often glued together by tiny microbes.

GT_15Aug2014_Fig4

Images of the Greenland Ice Sheet near Kangerlugssuaq in west-central Greenland taken by a drone (UAV) used to evaluate the evolving albedo of the ice sheet surface during the summer melt season. At top left, Prof. Jason Box and Johnny Ryan, a Ph.D. student at Aberystwyth University, hold the drone they used. Top left, the drone takes a picture of the surface (and the operator, J. Ryan) on August 9, 2014 from low altitude, showing numerous cryoconite holes filled with black dust, grit, and soot that had accumulated in the winter snowpack, and melted out of the older ice below. Bottom, a higher-altitude image of the same area reveals sinuous melt streams and linear fractures, as well as small speckles of cryoconite holes on the ice sheet. Tents from the camp are also visible as colorful dots against the ice surface. 

ps. Professors Alun Hubbard and Niel Snooke at Aberystwyth University deserve a lot of credit for the UAV development.

About the author Jason Box

Dr. Jason Box has been investigating Greenland ice sheet sensitivity to weather and climate as part of 23 expeditions to Greenland since 1994. His time camping on the inland ice exceeds 1 year. Year 2012 brought a deeper level of insight as the scientific perspective shifts to examine the interactions ice with atmospheric and ocean systems, including the role of fire in darkening the cryosphere. As part of his academic enterprise, Box has authored or co-authored 50+ peer-reviewed publications related to Greenland cryosphere-climate interactions. Box instructed climatology courses at The Ohio State University 2003-2012. Box is now a Professor at the Geological Survey of Denmark and Greenland (GEUS). Box was a contributing author to the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change 2007 4th assessment report. Box is also the former Chair of the Cryosphere Focus Group of the American Geophysical Union.

All posts by Jason Box →

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