JWG C.1: Climate Signatures in Earth Orientation Parameters

Chair: Jolanta Nastula (Poland)
Vice-Chair: Henryk Dobslaw (Germany)
(Affiliation: Commission 3, GGOS, IERS)


Earth orientation parameters comprising variations of both the position of the rotational pole and the spin rate are precisely observed by modern space geodetic techniques for several decades already. Moreover, optical astrometric observations extending back in time over more than 100 years provide even carry information about the mass transport and mass distribution processes acting on Earth at historical times that might be explored to quantify slow and subtle variations in the Earth's climate. This working group will study the various contributors of the global and interactively coupled climate system to the observed changes of the Earth's orientation on time-scales from days to centennials. It will xplore possibilities to validate numerical climate models and its individual components by means of assessing the angular momentum budget and the associated torques. The working group will further investigate predictive limits of various Earth system state and flux variables in order to aid short- and long-term prediction of polar motion and changes in the length-of-day, and might ultimately foster the incorporation of Earth Orientation Parameters into contemporaneous global re-analyses of the Earth System by means of data assimilation.


  • Detection of climatic signals in Earth's rotation from days to centennials
  • Modelling of climatic trends on the Earth rotation from days to centennials
  • Assessment of angular momentum budgets of global numerical climate and Earth system models
  • Fusion of Earth rotation parameters and global geophysical fluid models by means of data assimilation 


  • Establishment of the "best practices" for deriving angular momentum and torque estimates from numerical climate model data
  • Contributions to the future development of the Global Geophysical Fluid Centre (GGFC) of the International Earth Rotation and Reference Systems Service (IERS)
  • Active participation at major geodetic conferences via both session proposals and contributing abstracts
  • Annual working group meetings aligned to a major geodetic conference


  • Christian Bizouard (France)
  • Sigrid Boehm (Austria)
  • Aleksander Brzezinski (Poland)
  • Benjamin Fong Chao (Taiwan)
  • Yavor Chapanov (Bulgaria)
  • Jianli Chen (USA)
  • Alexandre Couhert (France)
  • Robert Dill (Germany)
  • Alberto Escapa (Spain)
  • José Manuel Ferrandiz (Spain)
  • Laura Fernandez (Argentina)
  • Franziska Goettl (Germany)
  • Richard Gross (USA)
  • Robert Heinkelmann (Germany)
  • Sébastien Lambert (France)
  • Vladimir Pashkevich (Russia)
  • Elena Podladchikova (Belgium)
  • Cyril Ron (Czech Republic)
  • David Salstein (USA)
  • Michael Schindelegger (Germany)
  • Nikolay Sidorenkov (Russia)
  • Leonid Zotov (Russia)

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