Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet.
Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discha...
Published in: | Proceedings of the National Academy of Sciences |
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2015
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Online Access: | https://escholarship.org/uc/item/49v6g05n https://escholarship.org/content/qt49v6g05n/qt49v6g05n.pdf https://doi.org/10.1073/pnas.1413024112 |
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ftcdlib:oai:escholarship.org:ark:/13030/qt49v6g05n 2024-09-15T18:09:02+00:00 Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. Smith, Laurence C Chu, Vena W Yang, Kang Gleason, Colin J Pitcher, Lincoln H Rennermalm, Asa K Legleiter, Carl J Behar, Alberto E Overstreet, Brandon T Moustafa, Samiah E Tedesco, Marco Forster, Richard R LeWinter, Adam L Finnegan, David C Sheng, Yongwei Balog, James 1001 - 1006 2015-01-01 application/pdf https://escholarship.org/uc/item/49v6g05n https://escholarship.org/content/qt49v6g05n/qt49v6g05n.pdf https://doi.org/10.1073/pnas.1413024112 unknown eScholarship, University of California qt49v6g05n https://escholarship.org/uc/item/49v6g05n https://escholarship.org/content/qt49v6g05n/qt49v6g05n.pdf doi:10.1073/pnas.1413024112 public Proceedings of the National Academy of Sciences of the United States of America, vol 112, iss 4 Greenland ice sheet mass balance meltwater runoff remote sensing supraglacial hydrology Climate Action article 2015 ftcdlib https://doi.org/10.1073/pnas.1413024112 2024-06-28T06:28:20Z Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km(2) of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54-2.81 cm⋅d(-1)) indicate that the surface drainage system conveyed its own storage volume every <2 d to the bed. Moulin discharges mapped inside ∼52% of the source ice watershed for Isortoq, a major proglacial river, totaled ∼41-98% of observed proglacial discharge, highlighting the importance of supraglacial river drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056-0.112 km(3)⋅d(-1) vs. ∼0.103 km(3)⋅d(-1)), and when integrated over the melt season, totaled just 37-75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean. Article in Journal/Newspaper Greenland Ice Sheet Isortoq University of California: eScholarship Proceedings of the National Academy of Sciences 112 4 1001 1006 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Greenland ice sheet mass balance meltwater runoff remote sensing supraglacial hydrology Climate Action |
spellingShingle |
Greenland ice sheet mass balance meltwater runoff remote sensing supraglacial hydrology Climate Action Smith, Laurence C Chu, Vena W Yang, Kang Gleason, Colin J Pitcher, Lincoln H Rennermalm, Asa K Legleiter, Carl J Behar, Alberto E Overstreet, Brandon T Moustafa, Samiah E Tedesco, Marco Forster, Richard R LeWinter, Adam L Finnegan, David C Sheng, Yongwei Balog, James Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
topic_facet |
Greenland ice sheet mass balance meltwater runoff remote sensing supraglacial hydrology Climate Action |
description |
Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km(2) of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54-2.81 cm⋅d(-1)) indicate that the surface drainage system conveyed its own storage volume every <2 d to the bed. Moulin discharges mapped inside ∼52% of the source ice watershed for Isortoq, a major proglacial river, totaled ∼41-98% of observed proglacial discharge, highlighting the importance of supraglacial river drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056-0.112 km(3)⋅d(-1) vs. ∼0.103 km(3)⋅d(-1)), and when integrated over the melt season, totaled just 37-75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean. |
format |
Article in Journal/Newspaper |
author |
Smith, Laurence C Chu, Vena W Yang, Kang Gleason, Colin J Pitcher, Lincoln H Rennermalm, Asa K Legleiter, Carl J Behar, Alberto E Overstreet, Brandon T Moustafa, Samiah E Tedesco, Marco Forster, Richard R LeWinter, Adam L Finnegan, David C Sheng, Yongwei Balog, James |
author_facet |
Smith, Laurence C Chu, Vena W Yang, Kang Gleason, Colin J Pitcher, Lincoln H Rennermalm, Asa K Legleiter, Carl J Behar, Alberto E Overstreet, Brandon T Moustafa, Samiah E Tedesco, Marco Forster, Richard R LeWinter, Adam L Finnegan, David C Sheng, Yongwei Balog, James |
author_sort |
Smith, Laurence C |
title |
Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
title_short |
Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
title_full |
Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
title_fullStr |
Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
title_full_unstemmed |
Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. |
title_sort |
efficient meltwater drainage through supraglacial streams and rivers on the southwest greenland ice sheet. |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/49v6g05n https://escholarship.org/content/qt49v6g05n/qt49v6g05n.pdf https://doi.org/10.1073/pnas.1413024112 |
op_coverage |
1001 - 1006 |
genre |
Greenland Ice Sheet Isortoq |
genre_facet |
Greenland Ice Sheet Isortoq |
op_source |
Proceedings of the National Academy of Sciences of the United States of America, vol 112, iss 4 |
op_relation |
qt49v6g05n https://escholarship.org/uc/item/49v6g05n https://escholarship.org/content/qt49v6g05n/qt49v6g05n.pdf doi:10.1073/pnas.1413024112 |
op_rights |
public |
op_doi |
https://doi.org/10.1073/pnas.1413024112 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
112 |
container_issue |
4 |
container_start_page |
1001 |
op_container_end_page |
1006 |
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1810446425778028544 |