Tephraeinfluss auf Gletscherablation in Island seit 2010 (TIOGA-Ice2010+)
Paläontologie
Zusammenfassung der Projektergebnisse
This research was conducted in the wake of the massive eruption of Eyjafjallajökull volcano on Iceland in 2010 with its large worldwide socio-economic impact related to ash in the atmosphere and interruptions of air traffic. The DFG-funded project resulted in significantly new insights into the processes of the influence of volcanic tephra (clastic volcanic material ejected during an eruption) on glacier ablation. To our knowledge we obtained the first ever recorded dataset of fully automated long-term measurements of snow depth changes under tephra deposits. We could document that snow and ice surfaces react differently on a coverage by varying tephra material. For the case of tephra-covered ice surfaces, we developed three exemplary ablation models of different complexity, i.e. with different requirements regarding the number of input variables. We were able to show that temperature/radiation index models deliver the most reliable results when judging from the integrated performance over all orders of magnitude of tephra thickness which potentially result from volcanic eruptions. However, we were also able to clearly document that for supraglacial tephra deposits from the order of centimeters onwards, physics-based models which explicitly account for the thermal conductivity of the tephra layer, have the greatest potential. We compiled a comprehensive set of 46 tephra samples from all volcanic regions throughout Iceland and used this dataset to derive relations between tephra grain thermal conductivity on the one hand and rock properties and composition on the other hand. Based on a detailed laboratory analysis we could clearly work out that tephra grain density is by far the most important predictor for thermal conductivity. In an extensive modeling study were able to show that the thermal conductivity of tephra grains could to a reasonable degree be modeled on the basis of density information only. However, additional information from the geochemical composition can be used to further improve the accuracy of the modeling results. The combined usage of the glaciological and geochemical/petrophysical modeling approaches developed in the framework of this project resulted in an integrated workflow that is able to quantify the influence of explosive volcanic eruptions on glacier ablation. Opportunities for further research are provided by transferring the developed models into spatially distributed calculation schemes on the basis of additional remote sensing data. With this extension, it will be possible to account for the full influence of volcanic tephra fallout on the mass balance of Icelandic ice masses and hence, its influence on top of climate variability.
Projektbezogene Publikationen (Auswahl)
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(2014): Evaluation of empirical approaches for modeling glacier ablation under volcanic tephra covers. IGS Nordic Branch Meeting, October 2014, Vik, Iceland
Möller, R., P.A. Kukla, M. Möller & C. Schneider
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(2015): Impact of ashfalls from Eyjafjallajökull and Grímsvötn volcanoes on glacier ablation on Iceland – a field experiment. AGU Fall Meeting, December 2015, San Francisco, USA
Möller, R., M. Möller, P.A. Kukla & C. Schneider
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(2015): Spatial and temporal patterns of albedo changes on Icelandic ice caps as a result of the 2010 Eyjafjallajökull volcanic eruption. IUGG General assembly, June 2015, Prague, Czech Republic
Möller, R., P.A. Kukla & C. Schneider
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(2016): Analyzing the complex relationship between spectral reflectance, surface temperatures and thickness of supra-glacial tephra deposits from the eruption of Eyjafjallajökull volcano in 2010. AGU Fall Meeting, December 2016, San Francisco, USA
Möller, R., M.T. Gudmundsson, M. Möller, W. Römer, F. Lehmkuhl, P.A. Kukla & C. Schneider
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(2016): Impact of supraglacial deposits of tephra from Grímsvötn volcano, Iceland, on glacier ablation. J. Glaciol., 62(235), 933- 943
Möller, R., Möller, M., Kukla, P.A. & Schneider, C.
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(2018): Modulation of glacier ablation by tephra coverage from Eyjafjallajökull and Grímsvötn volcanoes, Iceland: an automated field experiment. Earth Syst. Sci. Data, 10(1), 53-60
Möller, R., Möller, M., Kukla, P.A. & Schneider, C.
