GreenCrust: Tracing a Greenland’s crustal structure under the ice with geophysical inversion and an assessment of geothermal heat flow
Final Report Abstract
Greenland's ice mass loss has been one of the largest contributors to global sea level rise since the early 2000s. However, the mechanisms driving the mass loss are not fully understood, and particularly large uncertainties are associated with the conditions under the ice. In our project, we have (i) contributed to a new database of heat flow measurements for Greenland and especially their statistical evaluation applying machine learning. Despite the new database, competing models are commonly used in literature and their implications for ice sheet dynamics have been assessed in (ii). An especially suspicious observation point is the NGRIP (North Greenland Ice Core Project) measurement in Central Greenland and (iii) from statistical analysis, it could be shown that this point has to be treated as an outlier, at least for estimating regional heat flow. This has implications for the crustal contribution to heat flow as shown (iv) by a stepwise modelling of the lithospheric structure of Greenland. Lacking in this lithospheric scale model, is well-constrained information on thermal parameters of the crust and (v) therefore, we measured new samples from Greenland and compared these to estimates available from global databases. These data and models are used as input for (vi) a high-resolution crustal model for Greenland, where we specifically addressed the sub-ice geology and provided an estimate of the potential contribution of the crust to heat flow under the ice.
Publications
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A new strategy for aeromagnetic survey merging and application to Greenland. Poster for the Annual Meeting of the German Geophysical Society.
Freienstein, J., Szwillus, W., Heincke, B., Dilixiati, Y. & Ebbing, J.
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Greenland Geothermal Heat Flow Database and Map (Version 1). Earth System Science Data, 14(5), 2209-2238.
Colgan, William; Wansing, Agnes; Mankoff, Kenneth; Lösing, Mareen; Hopper, John; Louden, Keith; Ebbing, Jörg; Christiansen, Flemming G.; Ingeman-Nielsen, Thomas; Liljedahl, Lillemor Claesson; MacGregor, Joseph A.; Hjartarson, Árni; Bernstein, Stefan; Karlsson, Nanna B.; Fuchs, Sven; Hartikainen, Juha; Liakka, Johan; Fausto, Robert S.; Dahl-Jensen, Dorthe ... & Løkkegaard, Anja
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A new magnetic compilation from Greenland built by a combination of equivalent source modeling and spherical harmonic expansion. Greenland Portal
Heincke, B.H.,, Szwilius, W., Freienstein, J. & Ebbing, J.
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Evaluating different geothermal heat-flow maps as basal boundary conditions during spin-up of the Greenland ice sheet. The Cryosphere, 18(1), 387-402.
Zhang, Tong; Colgan, William; Wansing, Agnes; Løkkegaard, Anja; Leguy, Gunter; Lipscomb, William H. & Xiao, Cunde
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Greenland’s lithospheric structure and its implications for geothermal heat flow. PhD thesis at Kiel University.
Wansing, A.
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Statistical appraisal of geothermal heat flow observations in the Arctic. Solid Earth, 15(4), 513-533.
Freienstein, Judith; Szwillus, Wolfgang; Wansing, Agnes & Ebbing, Jörg
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The lithospheric structure of Greenland from a stepwise forward and inverse modelling approach. Geophysical Journal International, 238(2), 719-741.
Wansing, A.; Ebbing, J. & Moorkamp, M.
