On the Use of Interferometric Synthetic Aperture Radar (InSAR) for Monitoring the Dynamics of the Changing Earth
Jingyi "Ann" Chen (UT, Cockrell School of Engineering)
Fri, September 29, 10:30am - 11:30am
Host: Ginny Catania
Abstract: Interferometric Synthetic Aperture Radar (InSAR) techniques have already become central tools in the crustal deformation community; more recently, advances in InSAR have led to new applications including the analysis of the atmosphere, biosphere, cryosphere, and hydrosphere, as well as their mutual interactions. In this talk, we will discuss two recent advances in InSAR-based earth system applications. The first example is on the use of InSAR for characterizing groundwater levels and aquifer storage properties in confined aquifers over large agricultural basins such as the San Luis Valley, Colorado. With an improved image processing strategy, we revealed the 20-year trends in the temporal and spatial variability of the SLV confined aquifer system by combining L-band and C-band InSAR data from multiple satellite missions. We found very little change in the elastic aquifer storage properties with time, introducing the concept that calibration with a new well in an area would allow for the use of historical InSAR data to obtain head measurements before the time of well constructions. The second example focuses on the use of InSAR for permafrost research. Because the same mass of liquid water takes up less volume than ice, the surface settles as the active layer thaws in summer, with the opposite occurring in the fall. Based on this observation, an Active Layer Thickness (ALT) retrieval algorithm known as ReSALT has been developed and successfully applied to estimate ALT near Prudhoe Bay and Barrow, Alaska, with an uncertainty of ~ 10 cm using InSAR surface deformation data. Given that ReSALT estimates in hilly terrains tend to display a large bias with probing measurements, we have worked with L-band ALOS data near Toolik Lake, Alaska, to identify the dominate error sources in this scenario. Our Toolik results suggest that the InSAR-based ALT retrieval algorithm needs to take into account the impact of topography on the active layer water storage distribution. In addition, we discovered that InSAR observations could be utilized to better characterize the active layer thaw-freeze cycle. We believe that this finding highlights the critical role that InSAR data may play in better understanding the hydrologic state of permafrost terrain in the Arctic.
