Importance of Nisar Mission for Ice Sheet Studies

Abstract:

This presentation addresses how the synthetic-aperture radar (SAR) satellite mission under discussion between NASA and ISRO - entitled NISAR - will help us better understand and project the evolution of ice sheets and glaciers in a changing climate. NISAR is a dedicated L-band interferometry mission that will document changes in ice flow dynamics, grounding line positions and other critical boundaries over the lifetime of its mission. Changes in ice sheet dynamics represent by far the largest uncertainty in sea level projections. NISAR will better constrain critical boundaries of ice sheets at the base (basal friction) and at the seaward margins (ice melt rate) by providing the first set of continuous, systematic and comprehensive observations of ice sheet dynamics that will help us better understand ice sheets and glaciers and enable massive data assimilation in numerical ice sheet models. NISAR will contribute observations of areas of irreversible retreat taking place in Greenland and Antarctica, provide detailed time series of glacier velocities throughout entire seasonal cycles, document grounding line dynamics on weekly time scales, enable estimations of temporal and spatial changes in basal friction during glacial retreat; it will also in combination with other data help us map the bed topography of entire ice sheets at a high spatial resolution, document changes in ice shelf melt rate around the periphery of the continents, and provide a first systematic 3D vector mapping of ice velocity. NISAR will constitute a much needed warning system for ice sheet and ice shelf changes, it will document fundamental processes poorly observed in the past (e.g. calving, ice shelf melt, grounding line dynamics) and enable robust data assimilation to play a critical role in reducing uncertainties of coupled numerical models of ocean-ice-atmosphere interactions. This work was performed at UCI and JPL under a contract with NASA.