EGU25-12847, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-12847
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
The Earth Climate Observatory space mission concept for the monitoring of the Earth Energy Imbalance.
Steven Dewitte1, Thorsten Mauritsen2, Benoit Meyssignac3, Thomas August4, Luca Schifano4, Lien Smeesters5, Rémy Roca3, Helen Brindley6, Jacqueline Russell6, Nicolas Clerbaux7, Rainer Hollmann8, Linda Megner2, Margit Haberreiter9, Joerg Gumbel2, Jochem Marotzke10, Jérôme Riedi11, Aku Riihela12, Tim Trent13, and Manfred Wendisch14
Steven Dewitte et al.
  • 1ROB, Solar Physics and Space Weather, Brussels, Belgium (steven.dewitte@oma.be)
  • 2Stockholm University, Stockholm, Sweden
  • 3Laboratoire d'études en Géophysique et Océanographie Spatiales, Toulouse, France
  • 4European Space Agency, Noordwijk, Netherlands
  • 5Vrije Universiteit Brussel, Brussel, Belgium
  • 6Imperial College London, London, United Kingdom
  • 7Royal Meteorological Institute of Belgium, Brussels, Belgium
  • 8Deutscher Wetterdienst, Offenbach, Germany
  • 9Physical-Meteorological Observatory and World Radiation Center, Davos, Switzerland
  • 10Max Planck Institute for Meteorology, Hamburg, Germany
  • 11Lille University, Lille, France
  • 12Finnish Meteorological Institute, Helsinki, Finland
  • 13Earth Observation Science/National Centre for Earth Observation, School of Physics & Astronomy, University of Leicester, Leicester, United Kingdom
  • 14Leipzig University, Leipzig, Germany

Monitoring the Earth Energy Imbalance (EEI) is of prime importance for a predictive understanding of climate change. Furthermore, monitoring of the EEI gives an early indication on how well mankind is doing in implementing the Paris Climate Agreement. EEI is defined as the small difference between the incoming energy the Earth receives from the Sun and the outgoing energy lost by Earth to space. The EEI is cumulated in the Earth climate system, particularly in the oceans, due to their substantial heat capacity, and results in global temperature rise. Currently the best estimates of the absolute value of the EEI, and of its long term variation are obtained from in situ observations, with a dominant contribution of the time derivative of the Ocean Heat Content (OHC). These in situ EEI observations can only be made over long time periods, typically a decade or longer. In contrast, with direct observations of the EEI from space, the EEI can be measured at the annual mean time scale. However, the EEI is currently poorly measured from space, due to two fundamental challenges. The first fundamental challenge is that the EEI is the difference between two opposing terms of nearly equal amplitude. Currently, the incoming solar radiation and outgoing terrestrial radiation are measured with separate instruments, which means that their calibration errors are added and overwhelm the signal to be measured. To make significant progress in this challenge, a differential measurement using identical intercalibrated instruments to measure both the incoming solar radiation and the outgoing terrestrial radiation is needed. The second fundamental challenge is that the outgoing terrestrial radiation has a systematic diurnal cycle. Currently, the outgoing terrestrial radiation is sampled from the so-called morning and afternoon Sun-synchronous orbits, complemented by narrow band geostationary imagers. Recently the sampling from the morning orbit was abandoned. The sampling of the diurnal cycle can be improved, for example, by using two orthogonal 90° inclined orbits which give both global coverage, and a statistical sampling of the full diurnal cycle at seasonal time scale. For understanding the radiative forcing – e.g. aerosol radiative forcing - and climate feedback – e.g. ice albedo feedback - mechanisms underlying changes in the EEI, and for climate model validation, it is necessary to separate the Total Outgoing Radiation (TOR) spectrally into the two components of the Earth Radiation Budget (ERB), namely the Reflected Solar radiation (RSR) and Outgoing Longwave Radiation (OLR) and to map them at relatively high spatial resolution. The Earth Climate Observatory (ECO) mission concept was recently selected by the European Space Agency as one of the 4 candidate Earth Explorer 12 missions, that will be further studied in Phase 0 until mid 2026. The current paper provides a broad overview of the ECO mission objectives, the mission requirements, and the key elements of a baseline mission concept. During Phase 0, the ECO mission concept will be further elaborated in two parallel industrial studies, which may or may not adopt or refine the elements of the baseline concept.

How to cite: Dewitte, S., Mauritsen, T., Meyssignac, B., August, T., Schifano, L., Smeesters, L., Roca, R., Brindley, H., Russell, J., Clerbaux, N., Hollmann, R., Megner, L., Haberreiter, M., Gumbel, J., Marotzke, J., Riedi, J., Riihela, A., Trent, T., and Wendisch, M.: The Earth Climate Observatory space mission concept for the monitoring of the Earth Energy Imbalance., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12847, https://doi.org/10.5194/egusphere-egu25-12847, 2025.