Direct measurements of meltwater runoff on the Greenland ice sheet surface

Laurence C. Smith; Kang Yang; Lincoln H. Pitcher; Brandon T. Overstreet; Vena W. Chu; Åsa K. Rennermalm; Jonathan C. Ryan; Matthew G. Cooper; Colin J. Gleason; Marco Tedesco; Jeyavinoth Jeyaratnam; Dirk Van As; Michiel R. Van Den Broeke; Willem Jan Van De Berg; Brice Noël; Peter L. Langen; Richard I. Cullather; Bin Zhao; Michael J. Willis; Alun Hubbard; Jason E. Box; Brittany A. Jenner; Alberto E. Behar

doi:10.1073/pnas.1707743114

Direct measurements of meltwater runoff on the Greenland ice sheet surface

Laurence C. Smith^*, Kang Yang, Lincoln H. Pitcher, Brandon T. Overstreet, Vena W. Chu, Åsa K. Rennermalm, Jonathan C. Ryan, Matthew G. Cooper, Colin J. Gleason, Marco Tedesco, Jeyavinoth Jeyaratnam, Dirk Van As, Michiel R. Van Den Broeke, Willem Jan Van De Berg, Brice Noël, Peter L. Langen, Richard I. Cullather, Bin Zhao, Michael J. Willis, Alun HubbardJason E. Box, Brittany A. Jenner, Alberto E. Behar

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km² moulin-terminating internally drained catchment (IDC) on Greenland’s midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.

Original language	English
Pages (from-to)	E10622-E10631
Journal	Proceedings of the National Academy of Sciences of the United States of America
Volume	114
Issue number	50
DOIs	https://doi.org/10.1073/pnas.1707743114
Publication status	Published - 12 Dec 2017

Funding

ACKNOWLEDGMENTS. This project was funded by the NASA Cryosphere Program Grant NNX14AH93G managed by Dr. Thomas P. Wagner. DigitalGlobe WorldView imagery and geospatial support were provided by the Polar Geospatial Center (PGC) at the University of Minnesota with support from the National Science Foundation Awards 1043681 and 1559691 (all WorldView imagery Copyright DigitalGlobe, Inc.). Additional funding to K.Y. was provided by National Natural Science Foundation of China (41501452) and the Fundamental Research Funds for the Central Universities. Funding to M.T. was provided by NASA Grants NNX14AD98G and NNX16AH38G, and NSF Grant PLR-1643187. Funding to P.L.L. was provided by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement 610055 as part of the ice2ice project. The KAN_M weather station is funded by the Greenland Analogue Project (GAP) and is part of the weather station network of the Programme for Monitoring of the Greenland Ice Sheet (www.PROMICE.dk). M.J.W. acknowledges the University of North Carolina at Chapel Hill Research Computing group for computational resources and National Science Foundation Grant ARC-1111882. Polar Field Services, Inc. and Kangerlussuaq International Science Support (KISS) provided logistical support, with special thanks to Kathy Young, Susan Zager, and Kyli Cosper. Constructive requests from anonymous reviewers and the editor greatly strengthened the paper.

Keywords

Climate models
Fluvial catchment
Ice sheet meltwater runoff
Surface mass balance
Surface water hydrology

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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Smith, L. C., Yang, K., Pitcher, L. H., Overstreet, B. T., Chu, V. W., Rennermalm, Å. K., Ryan, J. C., Cooper, M. G., Gleason, C. J., Tedesco, M., Jeyaratnam, J., Van As, D., Van Den Broeke, M. R., Van De Berg, W. J., Noël, B., Langen, P. L., Cullather, R. I., Zhao, B., Willis, M. J., ... Behar, A. E. (2017). Direct measurements of meltwater runoff on the Greenland ice sheet surface. Proceedings of the National Academy of Sciences of the United States of America, 114(50), E10622-E10631. https://doi.org/10.1073/pnas.1707743114

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abstract = "Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland{\textquoteright}s midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.",

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year = "2017",

month = dec,

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doi = "10.1073/pnas.1707743114",

language = "English",

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Smith, LC, Yang, K, Pitcher, LH, Overstreet, BT, Chu, VW, Rennermalm, ÅK, Ryan, JC, Cooper, MG, Gleason, CJ, Tedesco, M, Jeyaratnam, J, Van As, D, Van Den Broeke, MR , Van De Berg, WJ, Noël, B, Langen, PL, Cullather, RI, Zhao, B, Willis, MJ, Hubbard, A, Box, JE, Jenner, BA & Behar, AE 2017, 'Direct measurements of meltwater runoff on the Greenland ice sheet surface', Proceedings of the National Academy of Sciences of the United States of America, vol. 114, no. 50, pp. E10622-E10631. https://doi.org/10.1073/pnas.1707743114

TY - JOUR

T1 - Direct measurements of meltwater runoff on the Greenland ice sheet surface

AU - Smith, Laurence C.

AU - Yang, Kang

AU - Pitcher, Lincoln H.

AU - Overstreet, Brandon T.

AU - Chu, Vena W.

AU - Rennermalm, Åsa K.

AU - Ryan, Jonathan C.

AU - Cooper, Matthew G.

AU - Gleason, Colin J.

AU - Tedesco, Marco

AU - Jeyaratnam, Jeyavinoth

AU - Van As, Dirk

AU - Van Den Broeke, Michiel R.

AU - Van De Berg, Willem Jan

AU - Noël, Brice

AU - Langen, Peter L.

AU - Cullather, Richard I.

AU - Zhao, Bin

AU - Willis, Michael J.

AU - Hubbard, Alun

AU - Box, Jason E.

AU - Jenner, Brittany A.

AU - Behar, Alberto E.

PY - 2017/12/12

Y1 - 2017/12/12

N2 - Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland’s midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.

AB - Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland’s midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.

KW - Climate models

KW - Fluvial catchment

KW - Ice sheet meltwater runoff

KW - Surface mass balance

KW - Surface water hydrology

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U2 - 10.1073/pnas.1707743114

DO - 10.1073/pnas.1707743114

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SN - 0027-8424

VL - 114

SP - E10622-E10631

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

IS - 50

ER -

Direct measurements of meltwater runoff on the Greenland ice sheet surface

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Keywords

UN SDGs

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