The Earth Climate Observatory: new space mission concept for monitoring the Earth Energy Imbalance
On 17 April 2024, the European Space Agency (ESA) selected the Earth Climate Observatory (ECO), a new space mission concept for the measurement of the Earth’s energy imbalance, a critical climate parameter, for Phase 0 study. ECO was proposed by an international team of 12 scientists led by the Royal Observatory of Belgium.
Climate change is fundamentally driven by the Earth’s energy imbalance (EEI). The measurement of the EEI from space is challenging, but it is needed to get an early indication on how well mankind is doing in the implementation of the Paris Climate Agreement.
The Earth energy imbalance is defined as the difference between the incoming solar radiation, and the sum of the reflected solar radiation and the emitted thermal radiation.
The EEI is the small difference between two nearly equal quantities: the incoming solar radiation and the outgoing terrestrial radiation. To reach an unprecedented accuracy, a differential measurement should be made with a single instrument: the wide field-of-view radiometer, which makes accurate albeit low-resolution observations.
To increase the spatial resolution, visible and thermal cameras can be used, which measure separately the reflected solar radiation and the emitted thermal radiation.
For sampling the diurnal cycle of the outgoing terrestrial radiation, a constellation of two orthogonal 90° inclination orbits provides global coverage, and a statistical sampling of the full diurnal cycle every three months.
Design of the wide field of view radiometer for the accurate differential measurement of the Earth energy imbalance.
The approval of the Phase 0 study, marks the start of the actual space mission development, which in the best case should lead to a launch in 2036 at the earliest.
ECO is proposed by a team of twelve scientists from the Royal Observatory of Belgium (Belgium), Stockholm University (Sweden), Legos/CNRS (France), Vrije Universiteit Brussel (Belgium), Imperial College (United Kingdom), Royal Meteorological Institute (Belgium), Deutscher Wetterdienst (Germany), the Belgian Climate Centre and PMOD/WRC (Switzerland).
Links:
ESA announcement: https://www.esa.int/Applications/Observing_the_Earth/FutureEO/Preparing_for_tomorrow/ESA_selects_four_new_Earth_Explorer_mission_ideas
Paper describing ECO mission concept: https://www.mdpi.com/2072-4292/15/23/5487