Improved 90-day Earth orientation predictions from angular momentum forecasts of atmosphere, ocean, and terrestrial hydrosphere

Abstract

Short-term forecasts of atmospheric, oceanic, and hydrological effective angular momentum functions (EAM) of Earth rotation excitation are combined with least-squares extrapolation and autoregressive modeling to routinely predict polar motion (PM) and $$\Delta \hbox {UT1}$$ for up to 90 days into the future. Based on hindcast experiments covering the years 2016 and 2017, a best performing parametrization was elaborated. At forecast horizons of 10 days, remaining prediction errors are 3.02 and 5.39 mas for PM and $$\Delta \hbox {UT1}$$ , respectively, corresponding to improvements of 34.5 and 44.7% when compared to predictions reported routinely in Bulletin A of the International Earth Rotation and Reference Systems Service. At forecast horizons of 60 days, prediction errors are 12.52 and 107.96 mas for PM and $$\Delta \hbox {UT1}$$ , corresponding to improvements of 34.5 and 8.2% over Bulletin A. The 90-day-long EAM forecasts leading to those improved EOP predictions are routinely published on a daily basis at isdc.gfz-potsdam.de/esmdata/eam.