Measuring Earth's Radiation Imbalance using Cubesat Constellations

At present, the global annual-mean Earth Radiation Imbalance (ERI), which can perturb the Earth's climate if non-zero, is estimated to be of order ~1 W/m^2 from ocean observations. However the uncertainty in satellite-based ERI is much larger than this estimate. Since measurements of ERI accurate to better than 0.5 W/m^2 are essential for understanding and predicting changes in our climate, new missions to determine ERI in conjunction with ongoing ocean observations are urgently needed. These missions should reliably determine Earth's radiation balance at the temporal and spatial scales sufficient for relating ERI to the physical processes responsible for variability.

The compelling objective of measuring ERI can be met using a constellation of satellites making global, high-frequency radiation measurements of the solar energy reflected and infrared energy radiated back to space with sufficient accuracy to determine the ERI to within 0.5 W/m^2. In this presentation, we discuss the reasons and prospects for deploying a Cubesat constellation to realize this objective, simulations of the data that could be produced by this constellation, and the advantages of the spatial coverage and high temporal frequency afforded by the constellation. These advantages apply both to estimating long-term ERI and to quantifying the radiation budgets of individual synoptic-scale weather systems. The innovations in this system involve both the use of Cubesats and of compact, continuously calibrated wide-field-of-view radiometers. We demonstrate the feasibility of such a constellation using the ongoing proof-of-concept deployment of the target radiometers onboard the upcoming NASA RAVAN (Radiometer Assessment using Vertically Aligned Nanotubes) mission.