Evaluation of selected short-term predictions of UT1-UTC and LOD collected in the second earth orientation parameters prediction comparison campaign

Abstract Advanced geodetic and astronomical tasks, such as precise positioning and navigation require forecasted Earth Orientation Parameters (EOP). The Second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC) aims to compare various EOP forecast methods implemented by different institutes from all over the world. Here we focus on universal time (UT1-UTC) and Length-of-Day (LOD) predictions received in the period between September 1st, 2021 and May 29th, 2022. The forecasts are preliminarily evaluated against the EOP 14 C04 solution delivered by the International Earth Rotation and Reference System Service (IERS) by using the mean absolute error (MAE) as the prediction quality measure. Exemplarily, we compare forecasts from IERS delivered by U.S. Naval Observatory (USNO) and a selected campaign participant to assess the impact of both input data and computation methodology on predictions. We show that improper treatment of long-periodic ocean tides has severely degraded LOD forecasting until this issue has been brought to the attention of the participant during a meeting of the 2nd EOP PCC. We consider this as a good example for the benefit of the campaign to the overall scientific community by providing specific feedback to individual processing centres on deficits in their products, which lead to quick and effective adaptations. The lessons learned from this analysis could be applied to other EOP forecasting methods based on Effective Angular Momentum (EAM) predictions. Graphical Abstract