Monitoring snowmelt across the Arctic forest–tundra ecotone using Synthetic Aperture Radar

Dean, Andrew Kristoffer; Brown, Ian A.; Huntley, Brian; Thomas, Chris

doi:10.1080/01431160600851793

Cited by 2 publications

(3 citation statements)

References 42 publications

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“…In Visttasvággi, the vegetation includes taller vegetation such as birches. When the radar encounters elements like tree trunks, leaves, and branches within a forest canopy, it experiences double bounce and volume scattering, typically resulting in higher backscatter [39]. The method used in this paper may be particularly effective for studying the snowmelt in areas without significant tree height variations due to the distinctive values obtained in such an environment.…”

Section: Variation In Backscattering and Spring Snowmeltmentioning

confidence: 99%

“…Sentinel-1 (S-1) SAR offers a 6-day revisit time at the equator, with 2 satellites in a 12-day orbit and a spatial resolution of around 20 m before speckle filtering [34]. Previous studies have used the SAR backscatter coefficient to measure the snowmelt and to generate snow cover maps [35][36][37], monitor snow wetness [38] and assess the relationship between the spring snowmelt and tundra vegetation changes [17,39].…”

Section: Introductionmentioning

confidence: 99%

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Synthetic Aperture Radar Monitoring of Snow in a Reindeer-Grazing Landscape

Carlsson,

Rosqvist,

Wennbom

et al. 2024

Remote Sensing

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Snow cover and runoff play an important role in the Arctic environment, which is increasingly affected by climate change. Over the past 30 years, winter temperatures in northern Sweden have risen by 2 °C, accompanied by an increase in precipitation. This has led to a higher incidence of thaw–freeze and rain-on-snow events. Snow properties, such as the snow depth and longevity, and the timing of snowmelt in spring significantly impact the alpine tundra vegetation. The emergent vegetation at the edge of the snow patches during spring and summer constitutes an essential nutrient supply for reindeer. We have used Sentinel-1 synthetic aperture radar (SAR) to determine the onset of the surface melt and the end of the snow cover in the core reindeer grazing area of the Laevás Sámi reindeer-herding community in northern Sweden. Using SAR data from March to August during the period 2017 to 2021, the start of the surface melt is identified by detecting the season’s backscatter minimum. The end of the snow cover is determined using a threshold approach. A comparison between the results of the analysis of the end of the snow cover from Sentinel-1 and in situ measurements, for the years 2017 to 2020, derived from an automatic weather station located in Laevásvággi reveals a 2- to 10-day difference in the snow-free ground conditions, which indicates that the method can be used to investigate when the ground is free of snow. VH data are preferred to VV data due to the former’s lower sensitivity to temporary wetting events. The outcomes from the season backscatter minimum demonstrate a distinct 25-day difference in the start of the runoff between the 5 investigated years. The backscatter minimum and threshold-based method used here serves as a valuable complement to global snowmelt monitoring.

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Section: Variation In Backscattering and Spring Snowmeltmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthetic Aperture Radar Monitoring of Snow in a Reindeer-Grazing Landscape

Carlsson,

Rosqvist,

Wennbom

et al. 2024

Remote Sensing

View full text Add to dashboard Cite

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“…Many models developed over the last 15 years have been validated in various environments, including mountainous terrain and glaciers [2][3][4], sea ice and ice sheets [5][6][7][8], agricultural fields [9,10], boreal forest [11][12][13][14][15][16], and forest-tundra ecotones [17]. The ability of SAR to discriminate snow-free from wet or dry snow-covered surfaces has been investigated substantially more than its potential for estimating the snow mass of dry snow cover; this is particularly true near the Arctic treeline.…”

Section: Introductionmentioning

confidence: 99%

C-Band SAR Imagery for Snow-Cover Monitoring at Treeline, Churchill, Manitoba, Canada

Pivot

2012

Remote Sensing

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RADARSAT and ERS-2 data collected at multiple incidence angles are used to characterize the seasonal variations in the backscatter of snow-covered landscapes in the northern Hudson Bay Lowlands during the winters of 1997/98 and 1998/99. The study evaluates the usefulness of C-band SAR systems for retrieving the snow water equivalent under dry snow conditions in the forest-tundra ecotone. The backscatter values are compared against ground measurements at six sampling sites, which are taken to be representative of the land-cover types found in the region. The contribution of dry snow to the radar return is evident when frost penetrates the first 20 cm of soil. Only then does the backscatter respond positively to changes in snow water equivalent, at least in the open and forested areas near the coast, where 1-dB increases in backscatter for each approximate 5-10 mm of accumulated water equivalent are observed at 20-31 incidence angles. Further inland, the backscatter shows either no change or a negative change with snow accumulation, which suggests that the radar signal there is dominated by ground surface scattering (e.g., fen) when not attenuated by vegetation (e.g., forested and transition). With high-frequency ground-penetrating radar, we demonstrate the presence of a 10-20-cm layer of black ice underneath the snow cover, which causes the reduced radar returns (−15 dB and less) observed in the inland fen. A correlation between the backscattering and the snow water equivalent cannot be determined due to insufficient observations at similar incidence angles. To establish a relationship between the snow water equivalent and the backscatter, only images acquired with similar incidence angles should be used, and they must be corrected for both vegetation and ground effects.

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Monitoring snowmelt across the Arctic forest–tundra ecotone using Synthetic Aperture Radar

Cited by 2 publications

References 42 publications

Synthetic Aperture Radar Monitoring of Snow in a Reindeer-Grazing Landscape

Synthetic Aperture Radar Monitoring of Snow in a Reindeer-Grazing Landscape

C-Band SAR Imagery for Snow-Cover Monitoring at Treeline, Churchill, Manitoba, Canada

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