Abstract
The largest uncertainty in future projections of sea level change comes from the uncertain response of the Antarctic Ice Sheet to the warming oceans and atmosphere. The ice sheet gains roughly 2000 km3 of ice from precipitation each year and losses a similar amount through solid ice discharge into the surrounding oceans. Numerous studies have shown that the ice sheet is currently out of long-term equilibrium, losing mass at an accelerated rate and increasing sea levels rise. Projections of sea-level change rely on accurate estimates of the contribution of land ice to the contemporary sea level budget. The longest observational record available to study the mass balance of the Earth’s ice sheets comes from satellite altimeters. This record, however, consists of multiple satellite missions with different life-spans, inconsistent measurement types (radar and laser) and of varying quality. To fully utilize these data, measurements from different missions must be cross-calibrated and integrated into a consistent record of change. Here, we present a novel approach for generating such a record. We describe in detail the advanced geophysical corrections applied and the processes needed to derive elevation change estimates. We processed the full archive record of satellite altimetry data, providing a seamless record of elevation change for the Antarctic Ice Sheet that spans the period 1985 to 2020. The data are produced and distributed as part of the NASA MEaSUREs ITS_LIVE project (Nilsson et al., 2021).
Highlights
The single largest uncertainty in multi-centennial projections of sea level change comes from the uncertain response of the Antarctic Ice Sheet to warming oceans and atmosphere (Oppenheimer et al, 2019)
We find an ice sheet wide error of -0.8 ± 7.8 derived from multi-mission synthesis (McMillan et al, 2014; Nilsson et al, 2016; Simonsen and Sørensen, 2017; Wouters et al, 2015)
In this study we have provided a 36-year record (1985-2020) of elevation change for the Antarctic ice sheet derived from seven altimetry missions combining both laser and radar measurements
Summary
The single largest uncertainty in multi-centennial projections of sea level change comes from the uncertain response of the Antarctic Ice Sheet to warming oceans and atmosphere (Oppenheimer et al, 2019). One of the most valued observational records comes from a handful of satellite altimeters that, in combination, provide a near-continuous record of elevation-change from 1992 (McMillan et al, 2014; Schröder et al, 2019; Shepherd et al, 2018, 2019; Zwally et al, 2015, 2021). Previous studies of the polar ice sheets that used data from a single satellite mission have been hampered by relatively short records over which to assess change. The creation of long-term records is essential for the separation of shortterm variability from long-term change Such records require piecing together observations from numerous satellite instruments, with unique measurement characteristics and sources of error. In support of the “Inter-mission Time Series of Land Ice Velocity and Elevation”
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