Universität zu Köln

Ullmann, Tobias ORCID: 0000-0002-6626-3052, Sauerbrey, Julia, Hoffmeister, Dirk ORCID: 0000-0002-8178-557X, May, Simon Matthias ORCID: 0000-0001-6762-7500, Baumhauer, Roland and Bubenzer, Olaf ORCID: 0000-0002-3199-1156 (2019). Assessing Spatiotemporal Variations of Sentinel-1 InSAR Coherence at Different Time Scales over the Atacama Desert (Chile) between 2015 and 2018. Remote Sens., 11 (24). BASEL: MDPI. ISSN 2072-4292

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Abstract

This study investigates synthetic aperture radar (SAR) time series of the Sentinel-1 mission acquired over the Atacama Desert, Chile, between March 2015 and December 2018. The contribution analyzes temporal and spatial variations of Sentinel-1 interferometric SAR (InSAR) coherence and exemplarily illustrates factors that are responsible for observed signal differences. The analyses are based on long temporal baselines (365-1090 days) and temporally dense time series constructed with short temporal baselines (12-24 days). Results are compared to multispectral data of Sentinel-2, morphometric features of the digital elevation model (DEM) TanDEM-X WorldDEM (TM), and to a detailed governmental geographic information system (GIS) dataset of the local hydrography. Sentinel-1 datasets are suited for generating extensive, nearly seamless InSAR coherence mosaics covering the entire Atacama Desert (>450 x 1100 km) at a spatial resolution of 20 x 20 meter per pixel. Temporal baselines over several years lead only to very minor decorrelation, indicating a very high signal stability of C-Band in this region, especially in the hyperarid uplands between the Coastal Cordillera and the Central Depression. Signal decorrelation was associated with certain types of surface cover (e.g., water or aeolian deposits) or with actual surface dynamics (e.g., anthropogenic disturbance (mining) or fluvial activity and overland flow). Strong rainfall events and fluvial activity in the periods 2015 to 2016 and 2017 to 2018 caused spatial patterns with significant signal decorrelation; observed linear coherence anomalies matched the reference channel network and indicated actual episodic and sporadic discharge events. In the period 2015-2016, area-wide loss of coherence appeared as strip-like patterns of more than 80 km length that matched the prevailing wind direction. These anomalies, and others observed in that period and in the period 2017-2018, were interpreted to be caused by overland flow of high magnitude, as their spatial location matched well with documented heavy rainfall events that showed cumulative precipitation amounts of more than 20 mm.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ullmann, Tobias UNSPECIFIED orcid.org/0000-0002-6626-3052 UNSPECIFIED Sauerbrey, Julia UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoffmeister, Dirk UNSPECIFIED orcid.org/0000-0002-8178-557X UNSPECIFIED May, Simon Matthias UNSPECIFIED orcid.org/0000-0001-6762-7500 UNSPECIFIED Baumhauer, Roland UNSPECIFIED UNSPECIFIED UNSPECIFIED Bubenzer, Olaf UNSPECIFIED orcid.org/0000-0002-3199-1156 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-124863
DOI:	10.3390/rs11242960
Journal or Publication Title:	Remote Sens.
Volume:	11
Number:	24
Date:	2019
Publisher:	MDPI
Place of Publication:	BASEL
ISSN:	2072-4292
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ZEBRA STRIPES; SAR; ARIDITY; ORIGIN; FOG Multiple languages Remote Sensing Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/12486