Rick Salvador: Final LOD model performance update

Talkshop readers will remember that as well as his work on modelling solar activity, Rick Salvador also built a planetary model to predict variation in Earth’s Length of Day (LOD). The model uses 13 frequencies derives from planetary and lunar motion to replicate changes in Earth’s spin rate.

Rick has retired from modelling now, so this is the final update on the model’s performance. The IERS LOD database was changed in early 2020, so the model performance update ends there. Over the last 4 years, Rick found that to keep it on track, he needed to add a -0.0006 second correction in June each year. The necessity for this is as yet unexplained and comments on possible reasons are encouraged.