Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers
Greenland ice sheet mass loss has accelerated in the past decade responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the abla...
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ftcopernicus:oai:publications.copernicus.org:tc14255 2023-05-15T16:21:30+02:00 Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers Box, J. E. Fettweis, X. Stroeve, J. C. Tedesco, M. Hall, D. K. Steffen, K. 2018-09-27 application/pdf https://doi.org/10.5194/tc-6-821-2012 https://tc.copernicus.org/articles/6/821/2012/ eng eng doi:10.5194/tc-6-821-2012 https://tc.copernicus.org/articles/6/821/2012/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-6-821-2012 2020-07-20T16:25:45Z Greenland ice sheet mass loss has accelerated in the past decade responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the ablation area. Using satellite-derived surface albedo with calibrated regional climate modeled surface air temperature and surface downward solar irradiance, we determine the spatial dependence and quantitative impact of the ice sheet albedo feedback over 12 summer periods beginning in 2000. We find that, while albedo feedback defined by the change in net solar shortwave flux and temperature over time is positive over 97% of the ice sheet, when defined using paired annual anomalies, a second-order negative feedback is evident over 63% of the accumulation area. This negative feedback damps the accumulation area response to warming due to a positive correlation between snowfall and surface air temperature anomalies. Positive anomaly-gauged feedback concentrated in the ablation area accounts for more than half of the overall increase in melting when satellite-derived melt duration is used to define the timing when net shortwave flux is sunk into melting. Abnormally strong anticyclonic circulation, associated with a persistent summer North Atlantic Oscillation extreme since 2007, enabled three amplifying mechanisms to maximize the albedo feedback: (1) increased warm (south) air advection along the western ice sheet increased surface sensible heating that in turn enhanced snow grain metamorphic rates, further reducing albedo; (2) increased surface downward shortwave flux, leading to more surface heating and further albedo reduction; and (3) reduced snowfall rates sustained low albedo, maximizing surface solar heating, progressively lowering albedo over multiple years. The summer net infrared and solar radiation for the high elevation accumulation area approached positive values during this period. Thus, it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming. Text glacier Greenland Ice Sheet North Atlantic North Atlantic oscillation Copernicus Publications: E-Journals Greenland The Cryosphere 6 4 821 839 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Greenland ice sheet mass loss has accelerated in the past decade responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the ablation area. Using satellite-derived surface albedo with calibrated regional climate modeled surface air temperature and surface downward solar irradiance, we determine the spatial dependence and quantitative impact of the ice sheet albedo feedback over 12 summer periods beginning in 2000. We find that, while albedo feedback defined by the change in net solar shortwave flux and temperature over time is positive over 97% of the ice sheet, when defined using paired annual anomalies, a second-order negative feedback is evident over 63% of the accumulation area. This negative feedback damps the accumulation area response to warming due to a positive correlation between snowfall and surface air temperature anomalies. Positive anomaly-gauged feedback concentrated in the ablation area accounts for more than half of the overall increase in melting when satellite-derived melt duration is used to define the timing when net shortwave flux is sunk into melting. Abnormally strong anticyclonic circulation, associated with a persistent summer North Atlantic Oscillation extreme since 2007, enabled three amplifying mechanisms to maximize the albedo feedback: (1) increased warm (south) air advection along the western ice sheet increased surface sensible heating that in turn enhanced snow grain metamorphic rates, further reducing albedo; (2) increased surface downward shortwave flux, leading to more surface heating and further albedo reduction; and (3) reduced snowfall rates sustained low albedo, maximizing surface solar heating, progressively lowering albedo over multiple years. The summer net infrared and solar radiation for the high elevation accumulation area approached positive values during this period. Thus, it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming. |
format |
Text |
author |
Box, J. E. Fettweis, X. Stroeve, J. C. Tedesco, M. Hall, D. K. Steffen, K. |
spellingShingle |
Box, J. E. Fettweis, X. Stroeve, J. C. Tedesco, M. Hall, D. K. Steffen, K. Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
author_facet |
Box, J. E. Fettweis, X. Stroeve, J. C. Tedesco, M. Hall, D. K. Steffen, K. |
author_sort |
Box, J. E. |
title |
Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
title_short |
Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
title_full |
Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
title_fullStr |
Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
title_full_unstemmed |
Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
title_sort |
greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-6-821-2012 https://tc.copernicus.org/articles/6/821/2012/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
glacier Greenland Ice Sheet North Atlantic North Atlantic oscillation |
genre_facet |
glacier Greenland Ice Sheet North Atlantic North Atlantic oscillation |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-6-821-2012 https://tc.copernicus.org/articles/6/821/2012/ |
op_doi |
https://doi.org/10.5194/tc-6-821-2012 |
container_title |
The Cryosphere |
container_volume |
6 |
container_issue |
4 |
container_start_page |
821 |
op_container_end_page |
839 |
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1766009507157114880 |