Direct Measurement of Earth’s Energy Imbalance with Geodetic Satellites – Feasibility Study (EEI-Geodetic)

• Applicant: Professor Dr.-Ing. Jürgen Kusche
• Subject Area: Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441179229

Earth’s Energy Imbalance (EEI) represents the difference between the energy absorbed and emitted by the Earth at the top of the atmosphere. Its long-term global mean is currently estimated to <0.9 W/m2. Several recent studies have pointed out the need to measure mean EEI with an accuracy of 0.1 W/m2 at larger spatial scales, and to detect possible long-term temporal changes. EEI at the top of the atmosphere is currently observed with the CERES family of satellite radiometers, but these sensors are known to have calibration problems at long timescales, so their mean has been anchored inestimates from ocean data. However, estimates of ocean heat change have their own problems due to sparsity of in-situ data such as Argo. Here we suggest to derive EEI from either indirect observation of solar and Earth’s radiation pressure with accelerometers or from satellite laser ranging. This is a very challenging objective, since it is not clear which accuracy the existing geodetic data base will allow for, and at which temporal and spatial resolution. We will develop a simulation framework that will enable testing and optimizing a dedicated EEI geodetic satellite, a constellation of such, or a future gravity mission such as GRACE-II equipped with improved accelerometers. The goal would be to validate, and possibly improve, the CERES-based estimates at large spatial scales (global mean,land-ocean-arctic partitioned, latitudinal bands) and at annual and longer timescales

• DFG Programme: Research Grants