GPS Interferometric Reflectometry Reveals Cyclic Elevation Changes in Thaw and Freezing Seasons in a Permafrost Area (Barrow, Alaska)

Abstract

Ground surface over permafrost area undergoes seasonal subsidence and uplift caused by the annual thawing and freezing of the active layer. Applying the Global Positioning System (GPS) interferometric reflectometry technique to the signal-to-noise ratio data collected by a continuously operating GPS station in a permafrost area in Barrow, we retrieve the daily surface elevation changes on snow-free days over a decade (2007–2016). Among these years, 2016 had the longest snow-free season, offering the longest and most complete records of elevation changes. Use this year as an example, we show that the ground subsided in thaw season and then uplifted from September to early November (freezing season) with an amplitude of 5.1 ± 0.2 cm. We also develop a composite model that includes both thaw and freeze indices to characterize the cyclic movements. Our composite model effectively explains the observed cyclic elevation changes and could be used in other permafrost studies.