MODIS-derived albedo changes of Vatnajökull (Iceland) due to tephra deposition from the 2004 Grímsvötn eruption

Möller, Rebecca; Möller, Marco; Björnsson, Helgi; Guðmundsson, Snævarr; Pálsson, Finnur; Oddsson, Björn; Kukla, Peter A.; Schneider, Christoph

doi:10.1016/j.jag.2013.08.005

Cited by 23 publications

(41 citation statements)

References 39 publications

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“…This would make the data barely useful for our long-term goal, which is to provide the albedo maps in a surface energy balance model applied on Icelandic glaciers. For the comparison with AWS data, we computed the actual or "blue-sky" albedo as the average between the black-sky albedo and the white-sky albedo assuming a constant fraction of diffuse illumination as done by [8]. In any case, the differences between the two albedo values are very low in high-latitude regions [8,17].…”

Section: Modis Albedomentioning

confidence: 99%

“…For instance, the role of albedo in the Greenland ice sheet mass balance has received much attention since its evolution could greatly affect Greenland´s contribution to sea level rise in addition to that caused by atmospheric warming alone [3][4][5][6]. In contrast, glaciers in Iceland hold only a 1 cm potential contribution to sea level rise [7] but they can undergo very large albedo variations due to the deposition of volcanic ashes during volcanic eruptions or by the blowing of ashes from previous eruptions during storms [8]. The volcanic ash is produced during explosive eruptions of the volcanoes in Iceland and can be transported by wind over tens of kilometers, depending on the atmospheric conditions and the particle properties [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…The MCD43A3 product [15] provides measurements of the global land surface spectral and broadband albedo on a 500 m resolution grid based on 16 days of multi-angular observations. MODIS data has been used to study the effect of the 2004 eruption in Grímsvötn on the albedo of Vatnajökull ice cap and how it evolves after the eruption [8]. Previous evaluation studies of the MODIS albedo product in glacier environments focused on the Greenland ice sheet [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Finally, albedo maps for Iceland are generated to quantify the effect of dust deposition on the albedo of the ice caps in the aftermath of the two aforementioned volcanic eruptions (Section 3.4). The previous version of the 16-days MODIS albedo (v005) albedo was evaluated in the period 2000-2008 using two stations on Tungnaárjökull, the western outlet glacier of Vatnajökull (AWSs tunef and tunmi, Figure 2) [8]. The RMSEs with respect to the in situ albedo for the two stations were 0.12 and 0.09 with no systematic deviations.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of MODIS Albedo Product over Ice Caps in Iceland and Impact of Volcanic Eruptions on Their Albedo

et al. 2017

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Albedo is a key variable in the response of glaciers to climate. In Iceland, large albedo variations of the ice caps may be caused by the deposition of volcanic ash (tephra). Sparse in situ measurements are insufficient to characterize the spatial variation of albedo over the ice caps due to their large size. Here we evaluated the latest MCD43 MODIS albedo product (collection 6) to monitor albedo changes over the Icelandic ice caps using albedo measurements from ten automatic weather stations on Vatnajökull and Langjökull. Furthermore, we examined the influence of the albedo variability within MODIS pixels by comparing the results with a collection of Landsat scenes. The results indicate a good ability of the MODIS product to characterize the seasonal and interannual albedo changes with correlation coefficients ranging from 0.47 to 0.90 (median 0.84) and small biases ranging from −0.07 to 0.09. The root-mean square errors (RMSE) ranging from 0.08 to 0.21, are larger than that from previous studies, but we did not discard the retrievals flagged as bad quality to maximize the amount of observations given the frequent cloud obstruction in Iceland. We found a positive but non-significant relationship between the RMSE and the subpixel variability as indicated by the standard deviation of the Landsat albedo within a MODIS pixel (R = 0.48). The summer albedo maps and time series computed from the MODIS product show that the albedo decreased significantly after the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions on all the main ice caps except the northernmost Drangajökull. A strong reduction of the summer albedo by up to 0.6 is observed over large regions of the accumulation areas. These data can be assimilated in an energy and mass balance model to better understand the relative influence of the volcanic and climate forcing to the ongoing mass losses of Icelandic ice caps.

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Section: Modis Albedomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of MODIS Albedo Product over Ice Caps in Iceland and Impact of Volcanic Eruptions on Their Albedo

et al. 2017

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“…The model formulation of Evatt et al (2015) is valid for all thicknesses from dust to meter scale. However, dedicated studies dealing with the relationship between tephra thickness and the intensity of induced ablation change are remarkably less numerous than those dealing with moraine debris, even if supraglacial tephra deposits are known to significantly influence glacier surface processes and mass balance (e.g., Kirkbride and Dugmore, 2003;Möller et al, 2014;Nield et al, 2013). So far, only three recent studies have carried out a systematic, quantitative investigation of the influence of tephra deposits of varying thickness on glacier ablation (Dragosics et al, 2016;Juen et al, 2013;Möller et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Modulation of glacier ablation by tephra coverage from Eyjafjallajökull and Grímsvötn volcanoes, Iceland: an automated field experiment

Möller

Kukla

et al. 2018

Earth Syst. Sci. Data

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Abstract.We report results from a field experiment investigating the influence of volcanic tephra coverage on glacier ablation. These influences are known to be significantly different from those of moraine debris on glaciers due to the contrasting grain size distribution and thermal conductivity. Thus far, the influences of tephra deposits on glacier ablation have rarely been studied. For the experiment, artificial plots of two different tephra types from Eyjafjallajökull and Grímsvötn volcanoes were installed on a snow-covered glacier surface of Vatnajökull ice cap, Iceland. Snow-surface lowering and atmospheric conditions were monitored in summer 2015 and compared to a tephra-free reference site. For each of the two volcanic tephra types, three plots of variable thickness ( ∼ 1.5, ∼ 8.5 and ∼ 80 mm) were monitored. After limiting the records to a period of reliable measurements, a 50-day data set of hourly records was obtained, which can be downloaded from the Pangaea data repository (https://www.pangaea.de; doi:10.1594/PANGAEA.876656). The experiment shows a substantial increase in snow-surface lowering rates under the ∼ 1.5 and ∼ 8.5 mm tephra plots when compared to uncovered conditions. Under the thick tephra cover some insulating effects could be observed. These results are in contrast to other studies which depicted insulating effects for much thinner tephra coverage on bare-ice glacier surfaces. Differences between the influences of the two different petrological types of tephra exist but are negligible compared to the effect of tephra coverage overall.

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Surface elevation change and mass balance of Icelandic ice caps derived from swath mode CryoSat‐2 altimetry

Foresta

Gourmelen

Pálsson

et al. 2016

Geophysical Research Letters

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We apply swath processing to CryoSat‐2 interferometric mode data acquired over the Icelandic ice caps to generate maps of rates of surface elevation change at 0.5 km postings. This high‐resolution mapping reveals complex surface elevation changes in the region, related to climate, ice dynamics, and subglacial geothermal and magmatic processes. We estimate rates of volume and mass change independently for the six major Icelandic ice caps, 90% of Iceland's permanent ice cover, for five glaciological years between October 2010 and September 2015. Annual mass balance is highly variable; during the 2014/2015 glaciological year, the Vatnajökull ice cap (~70% of the glaciated area) experienced positive mass balance for the first time since 1992/1993. Our results indicate that between glaciological years 2010/2011and 2014/2015 Icelandic ice caps have lost 5.8 ± 0.7 Gt a−1 on average, ~40% less than the preceding 15 years, contributing 0.016 ± 0.002 mm a−1 to sea level rise.

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MODIS-derived albedo changes of Vatnajökull (Iceland) due to tephra deposition from the 2004 Grímsvötn eruption

Cited by 23 publications

References 39 publications

Evaluation of MODIS Albedo Product over Ice Caps in Iceland and Impact of Volcanic Eruptions on Their Albedo

Evaluation of MODIS Albedo Product over Ice Caps in Iceland and Impact of Volcanic Eruptions on Their Albedo

Modulation of glacier ablation by tephra coverage from Eyjafjallajökull and Grímsvötn volcanoes, Iceland: an automated field experiment

Surface elevation change and mass balance of Icelandic ice caps derived from swath mode CryoSat‐2 altimetry

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