Independent Generation of Earth Orientation Parameters

Earth Orientation Parameters (EOPs) are fundamental geodetic parameters that describe the relative orientation of the Terrestrial Reference System and the Celestial Reference System. Their knowledge and therewith their highly accurate determination is indispensable for various applications in science and practice. In particular, EOPs are required for the realization of reference systems and time systems, for precise orbit determination, for navigation on Earth and in space as well as for positioning and surveying. Dependent on the application, EOPs are required as final products (i.e. at the highest possible accuracy but with a latency of a few weeks), as rapid products (i.e. in (near) real time with lower accuracy but with latencies between a few hours and minutes) or as predictions (with different accuracies for different prediction periods). The basis for the determination of EOPs at best possible accuracy are the observation data of the space geodetic observation techniques VLBI, SLR, GNSS and DORIS along with sophisticated strategies for their combination. The meaningful prediction of EOPs requires comprehensive theoretical knowledge concerning physical and empirical Earth rotation modelling as well as forecasts of the relevant excitations by processes within the various components in the Earth system, in particular in atmosphere, ocean, hydrosphere and the Earth’s interior.

Presently, ESA’s Navigation Support Office at ESOC is contributing to the realization of the International Terrestrial Reference Frame (ITRF) and combined EOP series in the framework of the International Earth Rotation Service (IERS). In this context, ESA is providing individual contributions to different scientific services of the International Association of Geodesy (IAG), in particular to the International Laser Ranging Services (ILRS), the International GNSS Service (IGS), the International DORIS Service (IDS) and the IERS. Ongoing ESA activities aim at providing contributions to the International VLBI Service (IVS) in near future.

The overall objective of the project is the prototype development of final, rapid and predicted EOP products, generated independently from external analysis centers. This objective shall be achieved through the following procedure:

  • Review of the existing algorithms, models and products for EOP generation
  • Review of ESA’s up-to-date involvement in reference frame and EOP activities and optimization of the processes and the product portfolio.
  • Selecting and testing models and concepts to describe and predict the EOP.
  • Developing a concept to optimally combine all available and future ESA reference frame products into a single EOP product.
  • Developing a prototype software tool to combine and predict ESA and external EOP products and demonstrate the performance of the prototype.

DGFI-TUM is leading the project consortium and is in particular responsible for the computation of highly accurate final EOP series from consistently combined observation data.

Selected Publications

Dill R., Dobslaw H., Hellmers H., Kehm A., Bloßfeld M., Thomas M., Seitz F., Thaller D., Hugentobler U., Schönemann E.: Evaluating Processing Choices for the Geodetic Estimation of Earth Orientation Parameters with Numerical Models of Global Geophysical Fluids. Journal of Geophysical Research: Solid Earth, 125(9), 10.1029/2020JB020025, 2020 (Open Access)
Hellmers H., Thaller D., Bloßfeld M., Kehm A., Girdiuk A.: Combination of VLBI Intensive Sessions with GNSS for generating Low latency Earth Rotation Parameters. Advances in Geosciences, 50, 49–56, 10.5194/adgeo-50-49-2019, 2019 (Open Access)

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