Non-Tidal Ocean Excitation Functions

Non-tidal ocean excitation functions (CHI) can be readily integrated into polar motion by means of the Liouville equation. Excitation functions consider the rotational deformation of the Earth and its associated passive response of equilibrium oceans, the relative angular momentum of the Earth's core, and the effects of mantle anelasticity. CHI is linearly derived from non-tidal ocean angular momentum as described by Gross (2009).

Operational Series

NameOcean ModelData SpanResolutionLatencyComments
ESMGFZ v1.2MPIOMJan 1976 to present3 hours1 dayIB removed

Ocean Model Experiments


 Ocean Model

Data Span



c20010701.chi MITgcm Jan 1980 to Mar 2002 1 day -
ECCO_50yr.chi MITgcm Jan 1949 to Dec 2002 10 days -
ECCO_kf066a2.chi MITgcm Jan 1993 to Dec 2008 1 day -
ECCO_kf066b.chi MITgcm Jan 1993 to Dec 2008 1 day -
ECCO_kf079.chi MITgcm Jan 1993 to Mar 2020 1 day -
ECCO_kf080i.chi MITgcm Jan 1993 to Mar 2020 1 day -

All available experiments can be downloaded here.

*FWF: Net-effects of freshwater fluxes from continental (and atmospheric) storages into the oceans are explicitly considered.

Gross, R. S. (2009), Earth Rotation Variations -- Long Period, In: Herring, T. (ed.), Treatise on Geophysics, Volume 3: Geodesy, p. 239-294, Elsevier, Amsterdam.


Dr. Henryk Dobslaw
Earth System Modelling