Temporal and Spatial Variations in the Radar Altimeter Signal Penetration Error in Greenland

Satellite altimetry is a primary method for monitoring dynamic changes in polar ice and snow. However, recent studies on extreme melting events have revealed the notable impact of radar altimeter signals penetrating through snow, challenging previous assumptions that monitoring imparted negligible effects. Current approaches for mitigating penetration errors offer only partial alleviation instead of complete elimination. This study estimates the penetration values of Greenland satellite monitoring from February 2004 to November 2020 by comparing the temporal sequence of elevation changes obtained from laser altimetry and radar altimetry. We investigated the temporal and spatial evolution characteristics of penetration, particularly focusing on the extreme melting event in 2019. Interestingly, laser altimeter signals are also determined to penetrate water bodies, introducing a potential source of inaccuracy in laser altimeter measurements during the melting season. Furthermore, the analysis estimated the impact of time-variable penetration depths on Greenland’s mass balance, revealing that regions with severe mass loss have the potential to exceed loss rates of 10 Gt/yr. These findings enhance our understanding of the impact of penetration errors in satellite altimetry and emphasize the crucial need for their correction to ensure accurate mass balance calculations in Greenland.