Earth's Energy Imbalance measured from Space with a CubeSat constellation
Résumé
The direct measurement of Earth's energy imbalance (EEI) and its variability is one of the greatest challenges in climate research. EEI represents a crucial quantity for testing climate models and for predicting the future course of global warming. In this context, we seek to implement a satellite constellation at Low Earth Orbit (LEO) to determine the absolute magnitude of global mean EEI. Thanks to a satellite constellation, it is possible to have short-term measurements of EEI at high spatiotemporal resolution. These measurements would allow constraining better poorly known radiative forcing associated with aerosols, aerosol-cloud interactions, surface albedo, and UV solar irradiance. The UVSQ-SAT CubeSat, launched January 24, 2021, represents our first pathfinder for a constellation to measure the EEI. The objective is to establish that miniaturized broadband radiometers absolutely calibrated through an extensive component level calibration program can be built and operated in space for measuring the components of the Earth's radiation budget (ERB) with an excellent accuracy. After introducing the importance of the ERB measurements, we will present the UVSQ-SAT mission and its scientific objectives. Then, the observations carried out by the UVSQ-SAT small satellite during the year 2021 will be shown (outgoing shortwave radiations (or albedo), and outgoing longwave radiations at the top of the atmosphere). Finally, we will present the lessons learned about the development of our first Earth science CubeSat, and we will present the second pathfinder CubeSat (INSPIRE-SAT 7) of this heterogeneous constellation. This CubeSat is scheduled for launch in 2023.