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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 9 | Copyright
The Cryosphere, 12, 2981-2999, 2018
https://doi.org/10.5194/tc-12-2981-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 21 Sep 2018

Research article | 21 Sep 2018

Seasonal mass variations show timing and magnitude of meltwater storage in the Greenland Ice Sheet

Jiangjun Ran1, Miren Vizcaino1, Pavel Ditmar1, Michiel R. van den Broeke2, Twila Moon3, Christian R. Steger2, Ellyn M. Enderlin4, Bert Wouters2, Brice Noël2, Catharina H. Reijmer2, Roland Klees1, Min Zhong5, Lin Liu6, and Xavier Fettweis7 Jiangjun Ran et al.
  • 1Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, the Netherlands
  • 2Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, the Netherlands
  • 3National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences,University of Colorado, Boulder, CO, USA
  • 4Climate Change Institute and School of Earth and Climate Science, University of Maine, Orono, ME, USA
  • 5State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics,Chinese Academy of Sciences, Wuhan, China
  • 6Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, China
  • 7Department of Geography, University of Liège, Liège, Belgium

Abstract. The Greenland Ice Sheet (GrIS) is currently losing ice mass. In order to accurately predict future sea level rise, the mechanisms driving the observed mass loss must be better understood. Here, we combine data from the satellite gravimetry mission Gravity Recovery and Climate Experiment (GRACE), surface mass balance (SMB) output of the Regional Atmospheric Climate Model v. 2 (RACMO2), and ice discharge estimates to analyze the mass budget of Greenland at various temporal and spatial scales. We find that the mean rate of mass variations in Greenland observed by GRACE was between −277 and −269Gtyr−1 in 2003–2012. This estimate is consistent with the sum (i.e., −304±126Gtyr−1) of individual contributions – surface mass balance (SMB, 216±122Gtyr−1) and ice discharge (520±31Gtyr−1) – and with previous studies. We further identify a seasonal mass anomaly throughout the GRACE record that peaks in July at 80–120Gt and which we interpret to be due to a combination of englacial and subglacial water storage generated by summer surface melting. The robustness of this estimate is demonstrated by using both different GRACE-based solutions and different meltwater runoff estimates (namely, RACMO2.3, SNOWPACK, and MAR3.9). Meltwater storage in the ice sheet occurs primarily due to storage in the high-accumulation regions of the southeast and northwest parts of Greenland. Analysis of seasonal variations in outlet glacier discharge shows that the contribution of ice discharge to the observed signal is minor (at the level of only a few gigatonnes) and does not explain the seasonal differences between the total mass and SMB signals. With the improved quantification of meltwater storage at the seasonal scale, we highlight its importance for understanding glacio-hydrological processes and their contributions to the ice sheet mass variability.

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To accurately predict future sea level rise, the mechanisms driving the observed mass loss must be better understood. Here, we combine data from the satellite gravimetry, surface mass balance, and ice discharge to analyze the mass budget of Greenland at various temporal scales. This study, for the first time, suggests the existence of a substantial meltwater storage during summer, with a peak value of 80–120 Gt in July. We highlight its importance for understanding ice sheet mass variability
To accurately predict future sea level rise, the mechanisms driving the observed mass loss must...
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