Comparison of Satellite Altimetry to Tide Gauge Measurement of Sea Level: Predictions of Glacio-Isostatic Adjustment

Abstract

Abstract Modern rates of sea level change are of interest because of concerns that global warming may be causing glacier retreat. Both tide gauges and satellite radar altimetry are used to measure the present rates of change in sea level. Tide gauges measure sea level relative to the ocean floor whereas the reference for satellite altimetry is the earth's center. A numerical model of deformation of the earth's solid surface and its geoid forced by melting ice sheets, both past and present, is used to predict the present rate of sea level change as measured by tide gauges and satellites. Sea level change observed by both tide gauges and satellites are predicted to be spatially nonuniform. Considering only past ice sheets tide gauges in glaciated regions would record a fall in sea level of −13 mm yr−1, whereas satellite altimetry would record a rise in sea level of 0.7 mm yr−1. In the region peripheral to the glaciated zone a tide gauge would record a rise in sea level (3 mm yr−1) in contrast to a predicted...