Relative sea level change in western Alaska estimated from satellite altimetry and repeat GPS measurements

Abstract

Western Alaska is a remote region populated by small coastal communities that are sensitive to variations in local relative sea level (RSL). The focus of this thesis is to address two main questions; what are the RSL trends in Western Alaska and what are the geophysical processes that contribute to the changes observed? Quantification of RSL variation requires measuring vertical velocities for both land surface motion (onshore component) and the ocean surface (offshore component). This study presents a new method for coastal satellite altimetry estimation, the collection of historic water level measurements, analysis of tide gauge measurements from various sources, GPS vertical velocity model for Western Alaska, estimation of an Earth model and glacial isostatic adjustment (GIA) vertical velocities for Northern and Western Alaska, and RSL change model for Western Alaska. The findings of this study result in a GIA model that predicts measured GPS velocities well. The predicted GIA vertical velocities average -1.06 mm/yr in Western Alaska and are combined with the averaged satellite altimetry cells that exhibit a mean sea level change offshore of Western Alaska of -0.27 mm/yr to produce a RSL change model for Western Alaska that increases approximately +0.79 mm/yr in the region.