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Abstract:
The Earth System Modelling group at GeoForschungsZentrum (GFZ) Potsdam offers now 6-day forecasts of Earth
rotation excitation due to atmospheric, oceanic, and hydrologic angular momentum changes that are consistent
with its 40 years-long EAM series. Those EAM forecasts are characterized by an improved long-term consistency
due to the introduction of a time-invariant high-resolution reference topography into the AAM processing that
accounts for occasional NWP model changes. In addition, all tidal signals from both atmosphere and ocean have
been separated, and the temporal resolution of both AAM and OAM has been increased to 3 hours. Analysis of an
extended set of EAM short-term hindcasts revealed positive prediction skills for up to 6 days into the future when
compared to a persistent forecast.
Whereas UT1 predictions in particular rely on an accurate AAM forecast, skillfull polar motion prediction
requires high-quality OAM forecasts as well. We will present in this contribution the results from a multi-year
hindcast experiment, demonstrating that the polar motion prediction as currently available from Bulletin A can
be improved in particular for lead-times between 2 and 5 days by incorporating OAM forecasts. We will also
report about early results obtained at Observatoire de Paris to predict polar motion from the integration of GFZ’s
6-day EAM forecasts into the Liouville equation in a routine setting, that fully takes into account the operational
latencies of all required input products.
