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Abstract:
The upcoming Libera mission, NASA’s first Earth Venture Continuity selection, will provide seamless continuity to current broadband radiance measurements obtained by the Clouds and Earth’s Radiant Energy System (CERES) project since March 2000. Leveraging advanced detector technologies, Libera will measure the broadband total, longwave, and shortwave radiances akin to CERES and carry a fourth radiometer to measure shortwave near-infrared radiances to advance our understanding of processes relevant to shortwave absorption by the climate system, radiative feedbacks, and Earth’s albedo variability with added insight into hemispheric albedo symmetry. We use Nimbus-7 observations, global model simulations and radiative transfer calculations to demonstrate applications of the added spectral knowledge in climate science. Although Libera’s absolute accuracy is unprecedented, it is insufficient to adequately close Earth’s energy budget. We will therefore discuss current and future avenues to indirectly and directly measure EEI from space. The latter is potentially feasible through sensing radiation pressure-induced accelerations acting on near-spherical spacecrafts, which under optimal conditions, are directly proportional to the net radiative flux experienced at the satellite’s location. This approach has been considered in the past, and the mission requirements to achieve a measurement accuracy within 0.3 Wm-2 are currently under investigation.
