Narrowband to broadband conversion of Landsat TM glacier albedos

Knap, Wouter; Reijmer, C. H.; Oerlemans, J.

doi:10.1080/014311699212362

Cited by 72 publications

(68 citation statements)

References 13 publications

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“…the albedo comprising the entire solar spectrum, is needed for mass balance calculations or other glaciological applications (Knap et al, 1999). This is nearly achieved in our study due to the large spectral range covered by APEX.…”

Section: Estimation Of Glacier Surface Albedomentioning

confidence: 61%

“…Cuffey & Paterson, 2010) and thus challenge the retrieval of ice surface albedo. Existing satellite-based approaches to distinguish glacierwide albedo values (Dumont et al, 2012;Knap, Reijmer, & Oerlemans, 1999;Paul, Machguth, & Kääb, 2005) typically suffer from a scaling mismatch since sampling distances (pixel sizes) are much coarser than albedo variability of the ice surface (e.g. Azzoni et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Imaging spectroscopy to assess the composition of ice surface materials and their impact on glacier mass balance

Naegeli

Damm

Huss

et al. 2015

Remote Sensing of Environment

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Glacier surfaces are not only composed of ice or snow but are heterogeneous mixtures of different materials. The occurrence and dynamics of light-absorbing impurities affect ice surface characteristics and strongly influence glacier melt processes. However, our understanding of the spatial distribution of impurities and their impact on ice surface characteristics and the glacier's energy budget is still limited. We use imaging spectroscopy in combination with in-situ experiments to assess the composition of ice surface materials and their respective impact on surface albedo and glacier melt rates. Spectroscopy data were acquired in August 2013 using the Airborne Prism EXperiment (APEX) imaging spectrometer and were used to map the abundances of six predominant surface materials on Glacier de la Plaine Morte, Swiss Alps. A pixel-based classification revealed that about 10% of the ice surface is covered with snow, water or debris. The remaining 90% of the surface can be divided into three types of glacier ice, namely~7% dirty ice,~43% pure ice and~39% bright ice. Spatially distributed spectral albedo derived from APEX reflectance data in combination with in-situ multi-angular spectroscopic measurements was used to analyse albedo patterns present on the glacier surface. About 85% of all pixels exhibit a low albedo between 0.1 and 0.4 (mean albedo 0.29 ± 0.12), indicating that Glacier de la Plaine Morte is covered with a significant amount of light-absorbing impurities, resulting in a strong ice-albedo feedback during the ablation season. Using a pixel-based albedo map instead of a constant albedo for ice (0.34) as input for a mass balance model revealed that the glacier-wide total ablation remained similar (10% difference). However, the large local variations in mass balance can only be reproduced using the pixel-based albedo derived from APEX, emphasizing the need to quantify spatial albedo differences as an important input for glacier mass balance models.

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Section: Estimation Of Glacier Surface Albedomentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Imaging spectroscopy to assess the composition of ice surface materials and their impact on glacier mass balance

Naegeli

Damm

Huss

et al. 2015

Remote Sensing of Environment

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“…Mean values of glacier-wide albedo retrieved from Landsat images at the Dongkemadi and XD glaciers. The albedo values in the table are the broadband albedo converted from the narrowband by using the method developed by Knap et al [71]. The Landsat imageries were collected in the summer, from June to September.…”

Section: Discussionmentioning

confidence: 99%

Annual Glacier-Wide Mass Balance (2000–2016) of the Interior Tibetan Plateau Reconstructed from MODIS Albedo Products

Zhang

Jiang

et al. 2018

Remote Sensing

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Glaciers in the Tibetan Plateau (TP) play a crucial role in regulating agriculture irrigation, river discharge and the regional/global climate system. However, mass balance records of TP glaciers have remained scarce due to challenging mountainous terrain and harsh weather conditions, which limits our understanding of the influence of melting glaciers on local water resources and responses to climate change. Here, we present and assess an albedo-based method to derive annual mass balance for three glaciers in the interior TP from Moderate Resolution Imaging Spectroradiometer (MODIS) albedo data during 2000-2016. A strong linear correlation (R 2 = 0.941, P < 0.001) is found between annual minimum-averaged glacier-wide albedo (AMGA) values and annual mass balance measurements on the Xiao Dongkemadi glacier. Furthermore, the 17-year-long annual mass balance series of the Xiao Dongkemadi glacier and the Geladandong mountain region glaciers, and the Purogangri ice cap are reconstructed for the first time, with a mass loss rate of 535 ± 63 mm w.e.a −1 , 243 ± 66 mm w.e.a −1 and 113 ± 68 mm w.e.a −1 , respectively. The results are verified by geodetic estimates, with relative error ranging from 4.55% to 11.80%, confirming that the albedo-based method can be used to estimate specific mass budgets for interior TP glaciers. A strong correlation between the mass balance series and air temperature infers that increasing summer air temperature may be one of main reasons for glacier shrinkage of the three studied glaciers.

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“…At S5, this was consistently around the 1st of June for the considered period, whereas at S6, this happens somewhere between mid-June and the beginning of July. Three narrowband pyranometers (Knap et al, 1999;Greuell and Oerlemans, 2004) that operated at S6 in 2004-2005 are used to explain why α cs and α cl become indiscernible over ice (see Table III for characteristics of these narrowband pyranometers). Two pairs of days were selected: 15 (cloudy) and 17 (clear) May 2005 both had a snow cover at S6, while at the 2nd (clear) and 5th (cloudy) of August, ice was at the surface.…”

Section: Application Ii: Clouds and Albedomentioning

confidence: 99%

Assessing the retrieval of cloud properties from radiation measurements over snow and ice

Munneke

Reijmer

Broeke

2011

Intl Journal of Climatology

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ABSTRACT:We critically review and improve a simple method to extract year-round records of cloud optical thickness from radiation measurements made by automatic weather stations (AWSs) over snow and ice surfaces. A 'longwaveequivalent cloudiness', N ε , obtained from longwave radiation measurements, is combined with the effective cloud optical thickness, τ , from shortwave data, to obtain consistent, year-round information on cloud properties. The method is applied to radiation data from six AWSs in Dronning Maud Land, Antarctica, and the ablation area of the West-Greenland ice sheet. The good correlation between daily-mean N ε and τ for all locations (0.77 < r < 0.94) shows that shortwave radiative properties of clouds can be inferred using longwave radiation even in the absence of solar radiation itself. An error analysis shows that retrievals of τ are sensitive to the quality of the input data, but accurate to about 21% for hourly values, 11% for daily means, and about 6% for monthly means. As three applications of the method presented above, we discuss the influence of clouds on the radiation budget (Application I), the relation between cloud cover and broadband albedo (Application II) at the six AWS locations, and we demonstrate the possibility to detect trends in τ in longer data series (Application III). About one-third of the attenuation of solar radiation by clouds is compensated by multiple reflections between the high-albedo surface and the cloud base (Application I). Cloudy-sky surface albedo is higher than the clear-sky albedo for snow surfaces but not for ice (Application II): over snow surfaces, clouds deplete near-infrared (IR) radiation and thus increase the broadband albedo. Ice surfaces have a much lower albedo for visible radiation, weakening this enrichment of visible radiation and thus the increase of broadband albedo. The method is used to detect a trend in τ of −0.40 ± 0.15 y −1 in the 1995-2004 time series from Neumayer, Antarctica (Application III).

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Narrowband to broadband conversion of Landsat TM glacier albedos

Cited by 72 publications

References 13 publications

Imaging spectroscopy to assess the composition of ice surface materials and their impact on glacier mass balance

Imaging spectroscopy to assess the composition of ice surface materials and their impact on glacier mass balance

Annual Glacier-Wide Mass Balance (2000–2016) of the Interior Tibetan Plateau Reconstructed from MODIS Albedo Products

Assessing the retrieval of cloud properties from radiation measurements over snow and ice

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