Abstract
We present a 1000 km transect of phase-sensitive radar measurements of ice thickness, basal reflection strength, basal melting, and ice-column deformation across the Ross Ice Shelf (RIS). Measurements were gathered at varying intervals in austral summer between 2015 and 2020, connecting the grounding line with the distant ice shelf front. We identified changing basal reflection strengths revealing a variety of basal conditions influenced by ice flow and by ice-ocean interaction at the ice base. Reflection strength is lower across the central RIS, while strong reflections in the near-front and near-grounding line regions correspond with higher basal melt rates, up to 0.47 ± 0.02 m a⁻¹ in the north. Melting from atmospherically warmed surface water extends 150-170 km south of the RIS front. Melt rates up to 0.29 ± 0.03 m a⁻¹ and 0.15 ± 0.03 m a⁻¹ are observed near the grounding lines of the Whillans and Kamb Ice Stream, respectively. Although troublesome to compare directly, our surface-based observations generally agree with the basal melt pattern provided by satellite-based methods but provide a distinctly smoother pattern. Our work delivers a precise measurement of basal melt rates across the RIS, a rare insight that also provides an early 21st century baseline.