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TerraSAR-X Time Series Fill a Gap in Spaceborne Snowmelt Monitoring of Small Arctic Catchments - A Case Study on Qikiqtaruk (Herschel Island), Canada

Stettner, Samuel and Lantuit, Hugues and Heim, Birgit and Eppler, Jayson and Roth, Achim and Bartsch, Annett and Rabus, Bernhard (2018) TerraSAR-X Time Series Fill a Gap in Spaceborne Snowmelt Monitoring of Small Arctic Catchments - A Case Study on Qikiqtaruk (Herschel Island), Canada. Remote Sensing in Ecology and Conservation, 10 (7), pp. 1-26. Wiley. DOI: 10.3390/rs10071155 ISSN 2056-3485

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Official URL: http://dx.doi.org/10.3390/rs10071155

Abstract

The timing of snowmelt is an important turning point in the seasonal cycle of small Arctic catchments. The TerraSAR-X (TSX) satellite mission is a synthetic aperture radar system (SAR) with high potential to measure the high spatiotemporal variability of snow cover extent (SCE) and fractional snow cover (FSC) on the small catchment scale. We investigate the performance of multipolarized and multi-pass TSX X-Band SAR data in monitoring SCE and FSC in small Arctic Tundra catchments of Qikiqtaruk (Herschel Island) off the Yukon Coast in the Western Canadian Arctic. We applied a threshold based segmentation on ratio images between TSX images with wet snow and a dry snow reference, and tested the performance of two different thresholds. We quantitatively compared TSX- and Landsat 8-derived SCE maps using confusion matrices and analyzed the spatiotemporal dynamics of snowmelt from 2015 to 2017 using TSX, Landsat 8 and in situ time lapse data. Our data showed that the quality of SCE maps from TSX X-Band data is strongly influenced by polarization and to a lesser degree by incidence angle. VH polarized TSX data performed best in deriving SCE when compared to Landsat 8. TSX derived SCE maps from VH polarization detected late lying snow patches that were not detected by Landsat 8. Results of a local assessment of TSX FSC against the in situ data showed that TSX FSC accurately captured the temporal dynamics of different snow melt regimes that were related to topographic characteristics of the studied catchments. Both in situ and TSX FSC showed a longer snowmelt period in a catchment with higher contributions of steep valleys and a shorter snowmelt period in a catchment with higher contributions of upland terrain. Landsat 8 had fundamental data gaps during the snowmelt period in all 3 years due to cloud cover. The results also revealed that by choosing a positive threshold of 1 dB, detection of ice layers due to diurnal temperature variations resulted in a more accurate estimation of snow cover than a negative threshold that detects wet snow alone. We find that TSX X-Band data in VH polarization performs at a comparable quality to Landsat 8 in deriving SCE maps when a positive threshold is used. We conclude that TSX data polarization can be used to accurately monitor snowmelt events at high temporal and spatial resolution, overcoming limitations of Landsat 8, which due to cloud related data gaps generally only indicated the onset and end of snowmelt.

Item URL in elib:https://elib.dlr.de/121158/
Document Type:Article
Title:TerraSAR-X Time Series Fill a Gap in Spaceborne Snowmelt Monitoring of Small Arctic Catchments - A Case Study on Qikiqtaruk (Herschel Island), Canada
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Stettner, SamuelUNSPECIFIEDUNSPECIFIED
Lantuit, HuguesUNSPECIFIEDUNSPECIFIED
Heim, BirgitUNSPECIFIEDUNSPECIFIED
Eppler, JaysonUNSPECIFIEDUNSPECIFIED
Roth, AchimAchim.Roth (at) dlr.deUNSPECIFIED
Bartsch, AnnettUNSPECIFIEDUNSPECIFIED
Rabus, BernhardUNSPECIFIEDUNSPECIFIED
Date:21 July 2018
Journal or Publication Title:Remote Sensing in Ecology and Conservation
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:10
DOI :10.3390/rs10071155
Page Range:pp. 1-26
Publisher:Wiley
ISSN:2056-3485
Status:Published
Keywords:Snow Cover Extent (SCE); TerraSAR-X; Landsat; wet snow; small Arctic catchments; satellite time series
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Remote sensing and geoscience
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Land Surface
Deposited By: Roth, Achim
Deposited On:30 Jul 2018 10:32
Last Modified:16 Jul 2019 05:03

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