Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-268
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
21 Nov 2016
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Reconstructions of the 1900–2015 Greenland ice sheet surface mass balance using the regional climate MAR model
Xavier Fettweis1, Jason E. Box2, Cécile Agosta1, Charles Amory1, Christoph Kittel1, and Hubert Gallée3 1Laboratory of Climatology, Department of Geography, University of Liège, Liège, Belgium
2Department of Glaciology and Climate, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark
3Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), Grenoble, France
Abstract. With the aim of studying the recent Greenland Ice Sheet (GrIS) Surface Mass Balance (SMB) decrease with respect to the last century, we have forced the regional climate MAR model (version 3.5.2) with the ERA-Interim (1979–2015), ERA-40 (1958–2001), NCEP-NCARv1 (1948–2015), NCEP-NCARv2 (1979–2015), JRA-55 (1958–2014), 20CRv2(c) (1900–2014) and ERA-20C (1900–2010) reanalysis. While all of these forcing products are reanalyses assumed to represent the same climate, they produce significant differences in the MAR simulated SMB over their common period. A temperature adjustment of +1 °C (respectively −1 °C) improved the accuracy of MAR boundary conditions from both ERA-20C and 20CRv2 reanalyses given that ERA-20C (resp. 20CRv2) is 1 °C colder (resp. warmer) over Greenland than ERA-Interim over 1980–2010. Comparisons with daily PROMICE near-surface observations validated these adjustments. Comparisons with SMB measurements from PROMICE, ice cores and satellite derived melt extent reveal the most accurate forcing data sets for simulating the GrIS SMB to be ERA-Interim and NCEP-NCARv1. However, some biases remain in MAR suggesting that some improvements need still to be done in its cloudiness and radiative scheme as well as in the representation of the bare ice albedo.

Results from all forcing simulations indicate: (i) the period 1961–1990 commonly chosen as a stable reference period for Greenland SMB and ice dynamics is actually a period when the SMB was anomalously positive (~ +10 %) compared to the last 120 years; (ii) SMB has decreased significantly after this reference period due to increasing and unprecedented melt reaching the highest rates in the 120 year common period; (iii) before 1960, both ERA-20C and 20CRv2 forced MAR simulations suggest a significant precipitation increase over 1900–1950 although this increase could be the result of an artefact in reanalysis not enough constrained by observations during this period. These MAR-based SMB and accumulation reconstructions are however quite similar to those from Box (2013) after 1930, which confirms the Box (2013)'s stationarity assumption of SMB over the last century. Finally, the ERA-20C forced simulation only suggests that SMB during the 1920–1930 warm period over Greenland was comparable to the SMB of the 2000's due to both higher melt and lower precipitation than normal.


Citation: Fettweis, X., Box, J. E., Agosta, C., Amory, C., Kittel, C., and Gallée, H.: Reconstructions of the 1900–2015 Greenland ice sheet surface mass balance using the regional climate MAR model, The Cryosphere Discuss., doi:10.5194/tc-2016-268, in review, 2016.
Xavier Fettweis et al.
Xavier Fettweis et al.
Xavier Fettweis et al.

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Short summary
This paper shows that the surface melt increase over the Greenland ice sheet since the end of the 1990's has been unprecedented in respect to the last 120 years with the help of a regional climate model forced by different reanalyses. These simulations suggest also an increase of the snowfall accumulation through the last century. Such a gain mass could have impacted the ice sheet dynamical stability and could explain the recent observed increase of the glaciers velocity.
This paper shows that the surface melt increase over the Greenland ice sheet since the end of...
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