Jason Box: Greenland albedo rebounds from snowfall but is again followed by widespread high air temperatures

Greenland albedo rebounds from snowfall but is again followed by widespread high air temperatures

by Jason Box, Melt Factor, August 1, 2012


In the latest update of daily Greenland reflectivity (a.k.a., albedo) observed by the NASA MODIS sensors, we see the effect of fresh snow brightening the ice sheet surface after the extreme low albedo in mid-July 2012. Late July’s reflectivity remains below other years in the observational record since 2000 and the values are trending lower again because of the darkening effect of near-surface air temperatures reported for July 24-31 being near or above the melting point, according to ground observations maintained by Konrad Steffen, director of the Swiss Federal Institute for Forest, Snow and Landscape Research. The earlier high melt area episode was  July 11-15, 2012.

Daily ice sheet averaged reflectivity values for 13 individual years beginning in 2000 (0-3200 m refers to the elevation range of the whole ice sheet).

If the July 24-31 high temperatures are on par with those from July 11-15, 2012, and if there is not another summer snowfall at the higher elevations of the ice sheet, I’d expect the albedos to decline further, reaching say 65.5% in the coming days.

These results are after the externally-reviewed publication Box et al. (2012) -- citation below.

• Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere Discuss., 6, 593-634, doi:10.5194/tcd-6-593-2012, 2012. DOWNLOAD LATEST ACCEPTED VERSION

Reflectivity (a.k.a. albedo) anomaly computed as the July average albedo for 5 km grid cells for the 12 year period (2000-2011) minus July 2012 values. Negative anomaly values mean the ice sheet is darker than average.

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