Greenland ice sheet record surface melting underway
by Jason Box, MeltFactor blog, July 23, 2012
While the potential impact of wildfires on darkening the Greenland ice sheet surface remain to be resolved, there is mounting evidence of an extreme year 2012 melt.
Melt signatures from active microwave remote sensing are stronger than in recent years over the upper areas of the ice sheet. Dark areas indicate absorption of the microwave signal emitted by the satellite. While, year 2010 and 2011 are recognized as being record melt years (Tedesco et al. 2011, van As et al. 2011), year 2012 melting appears to be more extensive.
On July 12, 2012, the Watson River bridge in Kangerlussuaq, west Greenland, has been swamped by higher river levels than have [ever] been observed. Watch the stunning videos here and here.
An elevated occurrence of above melting temperatures are observed 11-14 July near the ice sheet topographic summit in an area typically considered to be melt-free, a.k.a. the “dry snow zone.” The dates of the 4 consecutive days with near-surface air temperature above melting at the Summit station coincide with the Watson River flooding.
Thanks to Chris Biscan via Neven’s Arctic Sea Ice Blog for identifying an accessible source of Advanced Scatterometer (ASCAT) data.
Citations
While the potential impact of wildfires on darkening the Greenland ice sheet surface remain to be resolved, there is mounting evidence of an extreme year 2012 melt.
Melt signatures from active microwave remote sensing are stronger than in recent years over the upper areas of the ice sheet. Dark areas indicate absorption of the microwave signal emitted by the satellite. While, year 2010 and 2011 are recognized as being record melt years (Tedesco et al. 2011, van As et al. 2011), year 2012 melting appears to be more extensive.
On July 12, 2012, the Watson River bridge in Kangerlussuaq, west Greenland, has been swamped by higher river levels than have [ever] been observed. Watch the stunning videos here and here.
An elevated occurrence of above melting temperatures are observed 11-14 July near the ice sheet topographic summit in an area typically considered to be melt-free, a.k.a. the “dry snow zone.” The dates of the 4 consecutive days with near-surface air temperature above melting at the Summit station coincide with the Watson River flooding.
In my recently accepted albedo paper (Box et al. 2012, ACCEPTED VERSION), see abstract, the statement: “it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming” may be coming true already.
AcknowledementsThanks to Chris Biscan via Neven’s Arctic Sea Ice Blog for identifying an accessible source of Advanced Scatterometer (ASCAT) data.
Citations
- 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.
- Tedesco, M., Fettweis, X., van den Broeke, M. R., van de Wal, R. S. W., Smeets, C. J. P. P., van de Berg, W. J., Serreze, M. C., and Box, J. E.: The role of albedo and accumulation in the 2010 melting record in Greenland, Environ. Res. Lett., 6, 014005, http://dx.doi.org/10.1088/1748- 9326/6/1/014005doi:10.1088/1748-9326/6/1/014005, 2011.
- van As, D., Hubbard, A., Hasholt, B., Mikkelsen, A. B., van den Broeke, M., and Fausto, R. S.: Surface mass budget and meltwater discharge from the Kangerlussuaq sector of the Greenland ice sheet during record-warm year 2010, The Cryosphere Discuss., 5, 2319–2347, http://dx.doi.org/10.5194/tcd-5- 2319-2011doi:10.5194/tcd-5-2319-2011, 2011.
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