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Session A4: Atmospheric Effects, GNSS Remote Sensing, and Scientific Applications

Monitoring the Dynamic Motion of Landfast Ice in Alaska Using GNSS-Interferometric Reflectometry (GNSS-IR)
Jaclyn J. Bohn, Jihye Park, Oregon State University; Andrew Mahoney, Emily Fedders, University of Alaska Fairbanks
Location: Royal Ballroom DF
Date/Time: Thursday, Jan. 29, 9:20 a.m.

Peer Reviewed

Continuous monitoring of coastal water level and sea ice is crucial for coastal communities, marine wildlife, and navigation. However, limited observations have been collected in Alaska due to the lack of observational capability under extreme weather conditions. In this study, a GNSS-Interferometric Reflectometry (GNSS-IR) approach has been employed to continuously monitor sea ice in Nome, Alaska. Landfast ice, which remains stationary and anchored to the coastline, experiences tidal variations, though with less vertical movement than the open sea surface. In areas of bottom-fast ice or grounded ridges, this vertical motion is further diminished. Apart from this spatial variability of sea ice thickness, another challenge in measuring the motion of sea ice is due to the layer of snow accumulated on top of the ice. Since the fundamental approach of detecting displacement of sea ice using GNSS-IR involves estimating the height between a reflecting surface and a GNSS antenna, the layer of snow on the reflecting surface causes GNSS-IR to estimate the combined snow and sea ice height. Wavelet analysis of the GNSS-IR data, which combines sea ice and tidal motion, will yield frequencies spanning the lower and higher frequency spectrums. Tidal motion is a low-frequency, high amplitude signal compared to sea ice motion. These frequencies can be utilized to select appropriate cut-off frequencies for filtering. By applying a low-pass and high-pass filter with specified cutoff frequencies, tidal motion and dynamic motion of sea ice can be independently estimated.

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