Detection and Quantification of Snow Algae with an Airborne Imaging Spectrometer

Painter, T. H.; Duval, Brian; Thomas, William H.; Mendéz, Maria Sara Cabrera; Heintzelman, Sara; Dozier, Jeff

doi:10.1128/aem.67.11.5267-5272.2001

Cited by 129 publications

(169 citation statements)

References 17 publications

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“…If we knew the total quantity of algae in a given area of snow, we could multiply it by such an integrated rate to obtain daily CO 2 flux. Painter et al (26) in the Sierra Nevada Mountains of California have recently developed the use of remote sensing to estimate snow-algae densities: a trial scan of their field site found a mean concentration of 1,300 cells ml Ϫ1 over an area of 0.495 km 2 of snow. Recent reanalysis of their data suggests that the number should be closer to 300 cells ml Ϫ1 (T. H. Painter, personal communication).…”

Section: Discussionmentioning

confidence: 99%

Surface gas-exchange processes of snow algae

Williams

Gorton

Vogelmann

2003

Proc. Natl. Acad. Sci. U.S.A.

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The red-colored chlorophyte Chlamydomonas nivalis is commonly found in summer snowfields. We used a modified Li-Cor gas-exchange system to investigate surface gas-exchange characteristics of snow colonized by this alga, finding rates of CO2 uptake up to 0.3 μmol m−2⋅s−1 in dense algal blooms. Experiments varying the irradiance resulted in light curves that resembled those of the leaves of higher plants. Red light was more effective than white and much more effective than green or blue, because of the red astaxanthin that surrounds and masks the algal chloroplasts. Integrating daily course measurements of gas exchange showed CO2 uptake around 2,300 μmol⋅m−2⋅day−1 in heavily colonized patches, indicating that summer snowfields can be surprisingly productive

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Section: Discussionmentioning

confidence: 99%

Surface gas-exchange processes of snow algae

Williams

Gorton

Vogelmann

2003

Proc. Natl. Acad. Sci. U.S.A.

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“…Experimental results presented here, together with previous correlative observations [8][9][10][11][12][13][14][15][16] , laboratory experiments 17 , and theoretical calculations 18 , provide a compelling case for the magnitude of the glacier microbiome's effect on hydrology and climate. Snow algae amplify their albedo reduction through life history, population growth, dispersal, and physiology.…”

Section: Implications For High-latitude Ice Sheetsmentioning

confidence: 99%

“…Fresh snow reflects >90% of visible radiation, but during melt its grain size and water content increase, reducing albedo and further increasing snowmelt 1 . Impurities, including black carbon 3 , dust 4 , and resident microbes [7][8][9][10][11][12][13][14][15][16][17][18][19] , also lower albedo; however, microbes differ from non-living particulates in several critical ways. Perennial populations of photosynthetic microbes actively resurface following overwinter burial by snow 20 , and depend on liquid water and nutrients for survival and reproduction 13,14,[20][21][22] .…”

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confidence: 99%

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

et al. 2017

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A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of nitrogen-phosphorous-potassium fertilizer increased alga cell counts nearly fourfold, to levels similar to nitrogen-phosphorusenriched lakes; water alone increased counts by half. The manipulated alga abundance explained a third of the observed variability in snowmelt. Using a normalized-di erence spectral index we estimated alga abundance from satellite imagery and calculated microbial contribution to snowmelt on an icefield of 1,900 km 2 . The red-snow area extended over about 700 km 2 , and in this area we determined that microbial communities were responsible for 17% of the total snowmelt there. Our results support hypotheses that snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice. Radiative forcing due to perennial populations of microbes may match that of non-living particulates at high latitudes. Their contribution to climate warming is likely to grow with increased melt and nutrient input.G lacier ablation is sensitive to changes in albedo 1 , with atmospheric 2,3 , hydrological 4 and ecological 5,6 consequences. Fresh snow reflects >90% of visible radiation, but during melt its grain size and water content increase, reducing albedo and further increasing snowmelt 1 . Impurities, including black carbon 3 , dust 4 , and resident microbes [7][8][9][10][11][12][13][14][15][16][17][18][19] , also lower albedo; however, microbes differ from non-living particulates in several critical ways. Perennial populations of photosynthetic microbes actively resurface following overwinter burial by snow 20 , and depend on liquid water and nutrients for survival and reproduction 13,14,[20][21][22] . This requirement for liquid water in a frozen environment imposes a selective force favouring a physiology that increases melt proximal to cell walls. The generation of meltwater through microbes' albedoreducing properties motivates an hypothesis of bio-geophysical feedback on glacial landscapes 13,16 , such as the Greenland ice sheet. This feedback hypothesis, whereby microbes increase because they produce needed meltwater, is an active research area [13][14][15][16][17][18][19] , yet field experiments testing its assumptions are absent.Glacier microbiomes are water-limited 21,22 , because ice is generally not metabolically available, and oligotrophic, because their nutrient content equals that of precipitation plus deposition by airborne dust, pollen, and so on, with only limited N-fixation by local cyanobacteria 21,22 . Moreover, rapidly percolating water through large-grained snow may exacerbate both water-and nutrient limitation for algae in supraglacial...

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“…Partitioned estimates of GrIS mass loss have shown that surface melt contributes substantially to annual ice loss (Box, 2013;. Snow and ice surfaces become darker and have reduced visible-to-near-infrared (VNIR) reflectance and albedo due to the deposition of particulates, re-emergence of engrained particulates, biological activity, snow grain metamorphosis and the presence of melt (LaChapelle, 1969;Warren and Wiscombe, 1980;Kohshima et al, 1993;Painter et al, 2001;Takeuchi, 2009;Hodson et al, 2017). As surface melt is both a factor and result of surface darkening, the potential exists for a variety of melt-albedo feedbacks to further enhance shortwave absorption and accelerate melt, increasing mass loss and sea level rise contributions Tedesco et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

2017

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Abstract. We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period [2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016]. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500-2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

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Detection and Quantification of Snow Algae with an Airborne Imaging Spectrometer

Cited by 129 publications

References 17 publications

Surface gas-exchange processes of snow algae

Surface gas-exchange processes of snow algae

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

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