Overestimation and adjustment of Antarctic ice flow velocity fields reconstructed from historical satellite imagery

Abstract. Antarctic ice velocity maps describe the flow dynamics of sheet and are one primary components used to estimate mass balance contribution global sea level changes. In comparison derived from recent satellite images monthly weekly time spans, historical maps, before 1990s, generally cover longer e.g., over 10 years, due scarce spatial temporal coverage earlier image data. We found overestimations (OEs) in such long-span that can be mainly attributed gradients span used. general, they less significant slow-flowing grounded regions with low accelerations. Instead, take effect places high dynamics, for example, near grounding lines often shelf fronts. Velocities these areas important estimating analyzing instability. propose an innovative Lagrangian velocity-based method OE correction without use field observations or additional The is validated by using a set ground truth Totten Glacier Pine Island which produced high-quality Landsat 8 2013 2020. Subsequently, applied map David region 1972–1989 acquired during 1, 4, 5 missions. It demonstrated up 39 m a−1 195 effectively corrected. Furthermore, acceleration information, on basal melting calving activities, preserved corrected long-term analysis. Our experiment results (PIG) show OEs 15-year reach 1300 along line cause overestimated (GL) flux 11.5 Gt if not magnitudes contained both estimates significant. When alongside 1990s–2010s, may lead underestimated changes assessment forecast modeling climate change impact sheet. Therefore, must seriously examined recommend more than mapping uncertainty (1σ) This overestimation production regional ice-sheet-wide images.