Interferograms show phase differences of two radar images. Noisy areas are possible glaciers.
Team Location: Ames Research Center, Moffett Field, California
Authors: Daniel Sousa, Columbia University; Audrey Lee, University of California, Los Angeles; Owen Parker, San Francisco State University; Yamina Pressler, California Polytechnic State University, San Luis Obispo; Sammy Guo, Los Altos High School
Advisors/Mentors: Batuhan Osmanoglu, University of Alaska, Fairbanks; Cynthia Schmidt, Bay Area Environmental Research Institute
Other Acknowledgements: Michelle Newcomer, University of California, Berkeley; Amber Kuss, University of California, Santa Cruz
Abstract: Aleutian glaciers are sensitive indicators of global climatic processes and have been losing mass at greater rates since the mid-1990s than in previous decades. Direct observation of such glaciers in the field is plagued by inherent challenges including field access and difficulty obtaining useful optical imagery. Synthetic aperture radar (SAR) overcomes these challenges by using microwave frequency light to penetrate clouds, operate without sunshine and overcome spectral ambiguity, which enables monitoring not available through field campaigns alone. To evaluate recent changes in glacier dynamics, this study examined glaciers on the flanks of Isanotski volcano in the Aleutian Islands, Alaska. Two SAR techniques estimated glacier extent and velocity fields: 1) feature tracking and 2) interferometric coherence mapping. ENVI4.8 SARscape and ADORE-DORIS software were used to analyze archival data from both airborne (NASA UAVSAR) and satellite (ALOS-PALSAR and ERS 1 and 2) sensors. A digital elevation model (DEM) from the NASA Shuttle Radar Topography Mission (SRTM) was used during post-processing for terrain correction. Accuracy was assessed through comparison with manual digitization from SAR amplitude images. This procedure could be replicated worldwide to provide a consistent methodology for ongoing glacial evaluation.