An explanation for the dark region in the western melt zone of the Greenland ice sheet

Wientjes, I. G. M.; Oerlemans, J.

doi:10.5194/tcd-4-163-2010

Cited by 20 publications

(26 citation statements)

References 18 publications

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“…They used geochemical analyses and microscopy to show that the dust grains did not originate from volcanic eruptions or from low‐latitude deserts but rather that the dust was locally derived from nonglacierized parts of Greenland or nearby high‐latitude source areas experiencing high levels of aeolian activity. The occurrence of these darker dust‐rich zones on the ice sheet surface could provide an important positive feedback through the albedo‐controlled melt rate of ice [e.g., Bøggild et al , ; Wientjes and Oerlemans , ; Dumont et al , ]. Dust and organic material blown onto the ice can be dispersed or accumulated in cryoconite holes forming biological “hot spots” on the ice [ Yallop et al , ; Cook et al , ].…”

Section: High‐latitude Dust Entrainment Transport and Depositional mentioning

confidence: 99%

High‐latitude dust in the Earth system

et al. 2016

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Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high‐latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo‐aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high‐nutrient, low‐chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high‐latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year‐round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high‐latitude sources cover >500,000 km2 and contribute at least 80–100 Tg yr−1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

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Section: High‐latitude Dust Entrainment Transport and Depositional mentioning

confidence: 99%

High‐latitude dust in the Earth system

et al. 2016

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“…Typical measured values of albedo over the Greenland Ice Sheet are ;0.80 for dry snow, ;0.70 for wet snow, and ;0.50 for bare ice. Impurities can further reduce the latter value, for instance in the ''dark zone'' in the western part of the ice sheet (Wientjes and Oerlemans 2010). Some of the processes driving changes in albedo are snowfall and rainfall events, snow temperature, the occurrence of melt, and exposure of bare ice.…”

Section: Changes In Surface Albedomentioning

confidence: 99%

Greenland Surface Mass Balance as Simulated by the Community Earth System Model. Part I: Model Evaluation and 1850–2005 Results

et al. 2013

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This study presents the first twenty-first-century projections of surface mass balance (SMB) changes for the Greenland Ice Sheet (GIS) with the Community Earth System Model (CESM), which includes a new ice sheet component. For glaciated surfaces, CESM includes a sophisticated calculation of energy fluxes, surface albedo, and snowpack hydrology (melt, percolation, refreezing, etc.). To efficiently resolve the high SMB gradients at the ice sheet margins and provide surface forcing at the scale needed by ice sheet models, the SMB is calculated at multiple elevations and interpolated to a finer 5-km ice sheet grid. During a twenty-firstcentury simulation driven by representative concentration pathway 8.5 (RCP8.5) forcing, the SMB decreases from 372 6 100 Gt yr 21 in 1980-99 to 278 6 143 Gt yr 21 in 2080-99. The 2080-99 near-surface temperatures over the GIS increase by 4.7 K (annual mean) with respect to 1980-99, only 1.3 times the global increase (13.7 K). Snowfall increases by 18%, while surface melt doubles. The ablation area increases from 9% of the GIS in 1980-99 to 28% in 2080-99. Over the ablation areas, summer downward longwave radiation and turbulent fluxes increase, while incoming shortwave radiation decreases owing to increased cloud cover. The reduction in GIS-averaged July albedo from 0.78 in 1980-99 to 0.75 in 2080-99 increases the absorbed solar radiation in this month by 12%. Summer warming is strongest in the north and east of Greenland owing to reduced sea ice cover. In the ablation area, summer temperature increases are smaller due to frequent periods of surface melt.

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“…nivalis over the ice sheet (Lutz et al, 2014;Uetake et al, 2010;Takeuchi et al, 2014). The ice sheet is reportedly losing mass due to an increase in temperature and decrease in surface albedo during the last two decades (Rignot et al, 2008;Wientjes and Oerlemans, 2010;Box et al, 2012). Decline in surface albedo by snow and ice algal blooms can increase surface melt rates and thus is likely one of the factors to cause mass loss of the ice sheet in recent years (Yallop et al, 2012;Aoki et al, 2013;Lutz et al, 2014Lutz et al, , 2016Tedstone et al, 2017;Stibal et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Observations and modelling of algal growth on a snowpack in north-western Greenland

Onuma¹,

Takeuchi²,

Tanaka³

et al. 2018

The Cryosphere

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Abstract. Snow algal bloom is a common phenomenon on melting snowpacks in polar and alpine regions and can substantially increase snow melt rates due to the effect of albedo reduction on the snow surface. In order to reproduce algal growth on the snow surface using a numerical model, temporal changes in snow algal abundance were investigated on the Qaanaaq Glacier in north-western Greenland from June to August 2014. Snow algae first appeared at the study sites in late June, which was approximately 94 h after air temperatures exceeded the melting point. Algal abundance increased exponentially after this appearance, but the increasing rate became slow after late July, and finally reached 3.5 × 10 7 cells m −2 in early August. We applied a logistic model to the algal growth curve and found that the algae could be reproduced with an initial cell concentration of 6.9 × 10 2 cells m −2 , a growth rate of 0.42 d −1 , and a carrying capacity of 3.5 × 10 7 cells m −2 on this glacier. This model has the potential to simulate algal blooms from meteorological data sets and to evaluate their impact on the melting of seasonal snowpacks and glaciers.

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An explanation for the dark region in the western melt zone of the Greenland ice sheet

Cited by 20 publications

References 18 publications

High‐latitude dust in the Earth system

High‐latitude dust in the Earth system

Greenland Surface Mass Balance as Simulated by the Community Earth System Model. Part I: Model Evaluation and 1850–2005 Results

Observations and modelling of algal growth on a snowpack in north-western Greenland

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