Measuring glacier surface temperatures with ground‐based thermal infrared imaging

Aubry‐Wake, Caroline; Baraër, Michel; McKenzie, Jeffrey M.; Mark, Bryan G.; Wigmore, Oliver; Hellström, Robert; Lautz, Laura K.; Somers, Lauren

doi:10.1002/2015gl065321

Cited by 54 publications

(51 citation statements)

References 27 publications

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“…Lacking historical humidity and solar radiation records onsite, our temperature‐index glacier module provides a reasonable estimate of glacier melt (Fernàndez & Mark, ) with the available temperature data and compares well ( R 2 = 0.67) with observed historical glacier areas by López‐Moreno et al () (Figure a). However, the glacier module does not include edge‐effect feedback, in which longwave radiation from rock surrounding the glacier plays an increasingly important role as the glacier retreats (Aubry‐Wake et al, ), or elevation feedback, in which glacier thinning lowers the elevation of the glacier surface and is subjected to higher temperatures (Weertman, ). These unaccounted feedback make our glacier melt projections conservative estimates of mass loss through time.…”

Section: Resultsmentioning

confidence: 99%

Groundwater Buffers Decreasing Glacier Melt in an Andean Watershed—But Not Forever

Somers

McKenzie

Mark

et al. 2019

Geophysical Research Letters

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Accelerating mountain glacier recession in a warming climate threatens the sustainability of mountain water resources. The extent to which groundwater will provide resilience to these water resources is unknown, in part due to a lack of data and poorly understood interactions between groundwater and surface water. Here we address this knowledge gap by linking climate, glaciers, surface water, and groundwater into an integrated model of the Shullcas Watershed, Peru, in the tropical Andes, the region experiencing the most rapid mountain‐glacier retreat on Earth. For a range of climate scenarios, our model projects that glaciers will disappear by 2100. The loss of glacial meltwater will be buffered by relatively consistent groundwater discharge, which only receives minor recharge (~2%) from glacier melt. However, increasing temperature and associated evapotranspiration, alongside potential decreases in precipitation, will decrease groundwater recharge and streamflow, particularly for the RCP 8.5 emission scenario.

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Section: Resultsmentioning

confidence: 99%

Groundwater Buffers Decreasing Glacier Melt in an Andean Watershed—But Not Forever

Somers

McKenzie

Mark

et al. 2019

Geophysical Research Letters

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“…The transmissivity effect was too small (τ ≈ 1) to influence the results. Therefore, the infrared radiation balance measured by the IRT can be written as (Aubry‐Wake et al, 2015)

M_{λ} (T_{IRT}) = M_{λ} (T_{soil}) ε + M_{λ} (T_{refl}) (1 - ε)

with the temperature (K) measured by the IRT ( T IRT ), the temperature of the soil ( T soil ), and of the surrounding area ( T refl ); T refl was measured for every profile using a crumbled and reflattened piece of aluminum foil in front of the object of interest, which served as Lambert reflector with a low emissivity and thereby a high reflectivity (Fokaides and Kalogirou, 2011).…”

Section: Methodsmentioning

confidence: 99%

Influences of Macropores on Infiltration into Seasonally Frozen Soil

Demand

Selker

Weiler

2019

Vadose Zone Journal

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Core Ideas Macropores allow water infiltration into a frozen soil close to 0°C and at high water saturation. Connected biopores channel water beneath the frozen layer. Frozen layer thickness in relation to connected macroporosity is a crucial factor. Infrared thermography can be used to measure frozen layer extent and variability. Water frozen in soil can reduce the soil infiltrability, depending on the water content. We hypothesize that air‐filled macropores control the infiltration of a seasonally frozen soil under high saturation degrees. Sprinkling experiments with different intensities on a seasonally frozen soil were conducted in two winters at high initial water contents. Brilliant Blue FCF (BB) was sprinkled on four plots equipped with soil moisture and temperature probes to mark flow paths. Frozen layer thickness was measured with infrared thermography of soil sections and overlaid with BB images. The frost depth of the experiments was 8 to 15 cm. Infiltration rates showed reduced infiltration compared with unfrozen conditions. By impeding refreezing of the infiltrating water with added NaCl, infiltration rates of 23 to 29 mm h−1 were measured. Without the addition of salt, the infiltration rates decreased to 5 to 10 mm h−1, attributed to pore blockage by refreezing water. Temperature measurements revealed that the frozen layer only thawed close to the soil surface during the experiments. Blue‐stained areas indicated that water was channeled through the frozen layer into the unfrozen soil. In addition, the soil moisture probes below the frozen layer measured an increase in unfrozen water content, whereas total water content in the frozen layer was constant. These observations were explained by a connected air‐filled porosity, such as biopores, which allowed water flow even under high initial water contents. These results illustrate the importance of macroporosity in relation to frost depth in controlling the infiltrability of seasonally frozen soils.

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“…et al, 2016). Ground-based thermal infrared mapping of debris-covered glaciers has already been demonstrated (Aubry-Wake et al, 2015, but the recent advances in UAV-mounted thermal cameras have not yet been explored for this type of glacier.…”

Section: Introductionmentioning

confidence: 99%

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

et al. 2018

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A layer of debris cover often accumulates across the surface of glaciers in active mountain ranges with exceptionally steep terrain, such as the Andes, Himalaya, and New Zealand Alps. Such a supraglacial debris layer has a major influence on a glacier's surface energy budget, enhancing radiation absorption, and melt when the layer is thin, but insulating the ice when thicker than a few cm. Information on spatially distributed debris surface temperature has the potential to provide insight into the properties of the debris, its effects on the ice below and its influence on the near-surface boundary layer. Here, we deploy an unmanned aerial vehicle (UAV) equipped with a thermal infrared sensor on three separate missions over one day to map changing surface temperatures across the debris-covered Lirung Glacier in the Central Himalaya. We present a methodology to georeference and process the acquired thermal imagery, and correct for emissivity and sensor bias. Derived UAV surface temperatures are compared with distributed simultaneous in situ temperature measurements as well as with Landsat 8 thermal satellite imagery. Results show that the UAV-derived surface temperatures vary greatly both spatially and temporally, with −1.4 ± 1.8, 11.0 ± 5.2, and 15.3 ± 4.7 • C for the three flights (mean ± sd), respectively. The range in surface temperatures over the glacier during the morning is very large with almost 50 • C. Ground-based measurements are generally in agreement with the UAV imagery, but considerable deviations are present that are likely due to differences in measurement technique and approach, and validation is difficult as a result. The difference in spatial and temporal variability captured by the UAV as compared with much coarser satellite imagery is striking and it shows that satellite derived temperature maps should be interpreted with care. We conclude that UAVs provide a suitable means to acquire surface temperature maps of debris-covered glacier surfaces at high spatial and temporal resolution, but that there are caveats with regard to absolute temperature measurement.

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Measuring glacier surface temperatures with ground‐based thermal infrared imaging

Cited by 54 publications

References 27 publications

Groundwater Buffers Decreasing Glacier Melt in an Andean Watershed—But Not Forever

Groundwater Buffers Decreasing Glacier Melt in an Andean Watershed—But Not Forever

Influences of Macropores on Infiltration into Seasonally Frozen Soil

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

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