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Summary of Proposal LAN0586

TitleTerraSAR-X interferometry in the framework of the ESA DUE Permafrost Project
Investigator Strozzi, Tazio - Gamma Remote Sensing, N/A
Team Member
Dr. Wiesmann, Andreas - Gamma Remote Sensing, -
Dr. Bartsch, Annett - Vienna University of Technology, Institute of Photogrammetry and Remote Sensing
Muster, Sina - Alfred Wegener Institute for Polar and Marine Research,
SummaryThe goal of this project is to monitor land subsidence with SAR interferometry on 2 pan arctic test sites. This activity will be part of ESA’s DUE (Data User Element) PERMAFROST project (response to ESA ITT “AO/1-5688/08/I-EC STSE DUE Permafrost), that will start on June 1, 2009. Potential test-areas are North Slope, Alaska (USA), Mackenzie River Delta, Northwest Territories (Canada), Lena River Delta, Siberia (Russia), Yakutsk, Siberia (Russia), and Vorkuta, Pechora Urals (Russia). The complexity of the phenomenon permafrost requires the close cooperation with the scientific community of various disciplines that are brought together in the DUE Permafrost project. For creating the required information, multiple interferograms from different sensors (ERS-1/2, ENVISAT, ALOS, TerraSAR-X, Cosmo-Skymed) may be used in every case. Therefore, results obtained in the frame of this Science Service proposal with TerraSAR-X will be compared/integrated with those obtained from other SAR sensors. Depending on data availability, land and snow cover and topography various interferometric approaches (single interferograms, stacking, short-baseline InSAR, interferometric point target analysis) may be employed. The main results of the SAR interferometric analysis are maps of the averaged displacement rates on coherent targets in the satellite line-of-sight direction and temporal series of displacements on points of particular relevance. As additional elements, DEM generation with TerraSAR-X will be investigated in areas without significant ground motion and water bodies will be classified from the SAR intensity images.
Final ReportTerraSAR-X data were considered in the framework of the ESA DUE Permafrost Project (http://geo.tuwien.ac.at/permafrost). The general objective of the ESA project was to establish a pan-boreal monitoring system based on satellite data at local, regional and global scale. Parameters of the system include land surface temperature, soil moisture, snow cover, snow water equivalent, vegetation cover, water bodies, land subsidence, DEM and methane complemented by permafrost models. TerraSAR-X data were used for: --> the detection of long-term surface subsidence due to permafrost thaw, annual frost heave/thaw settlement of the active layer, and rapid mass wasting due to thermoerosion on the Mackenzie River Delta (Canada), Bathurst Island (Canada) and along the North Slope of Alaska; --> the classification of freshwater ice conditions on the Alaskan Arctic Coastal Plain; --> the detection of seasonal and interannual coastal erosion in Alaska. Arctic permafrost areas are subject to intense freezing cycles and characterized by remarkable surface displacement. We used TerraSAR-X InSAR data to analyse the surface displacement in the summer of 2010 and 2011 over a large area of the North Slope of Alaska along the Dalton Highway. Using floodplain areas as the reference for InSAR’s relative deformation measurements, we found maximum subsidence of about 4 cm during the thawing season. TerraSAR-X time-series of interferograms with 11 days time interval also highlight that subsidence is occurring rather quickly in summer. TerraSAR-X investigations can be however only based on interferograms acquired during the summer season, because of poor coherence under snow-cover conditions or for acquisition time intervals of one year or more. ALOS PALSAR interferograms were therefore used to complement the analysis, allowing the reconstruction of longer time-series of deformation showing summer thaw subsidence and winter frost heave. Arctic freshwater ecosystems have responded rapidly to climatic changes over the last half century. Lakes and rivers are experiencing a thinning of the seasonal ice cover, which may increase potential over-wintering freshwater habitat, winter water supply for industrial withdrawal, and permafrost degradation. We combined the use of high-resolution spotlight TerraSAR-X satellite data and ground penetrating radar to identify and characterize floating ice and grounded ice conditions in lakes, ponds, beaded stream pools, and an alluvial river channel. A GIS-based analysis of 890 surface water features larger than 0.01 ha showed that 42% of the total surface water area potentially provided over-wintering habitat during the 2012/2013 winter. Lakes accounted for 89% of this area, whereas the alluvial river channel accounted for 10% and ponds and beaded stream pools each accounted for <1%. Identification of smaller landscape features such as beaded stream pools may be important because of their distribution and role in connecting other water bodies on the landscape. These findings advance techniques for detecting and knowledge associated with potential winter habitat distribution for fish and invertebrates at the local scale in a region of the Arctic with increasing stressors related to climate and land use change. Analysis of a 60 km segment of the Alaskan Beaufort Sea coast using a time-series of aerial photography revealed that mean annual erosion rates increased from 6.8 m a-1 (1955 to 1979), to 8.7 m a-1 (1979 to 2002), to 13.6 m a-1 (2002 to 2007). Also spatial patterns of erosion have become more uniform across shoreline types with different degrees of ice-richness. Concurrent Arctic changes potentially responsible for this shift in the rate and pattern of land loss include declining sea ice extent, increasing summertime sea surface temperature, rising sea-level, and increases in storm power and corresponding wave action. Taken together, these factors may be leading to a new regime of ocean-land interactions that are repositioning and reshaping the Arctic coastline. We considered use of very-high resolution TerraSAR-X data for coastal erosion at Drew Point, Alaska. The satellite SAR images can be precisely co-register in the original radar images with an accuracy on the order of 1/10th of a pixel or better before geocoding, so that subtle changes can be observed. On the other hand, radar images are affected by speckle noise, which reduces visibility of ground features. In general, coastal erosion could be well observed between two late summer images acquired in 2010 and 2011, with maximum erosion on the order of 20 m. In early summer sea ice is disturbing the distinction of the coast.

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