Oceanic excitation of polar motion from intraseasonal to decadal periods

We study the oceanic excitation of polar motion by using six different time series of the non-tidal oceanic angular momentum which are either publicly available or more experimental in nature. The oceanic excitation series are compared to each other and to the difference between the excitation inferred from the polar motion data and the corresponding atmospheric contributions. Comparisons show good agreement between the observed residual excitation and most of the ocean series. By performing computations separately for the seasonal sinusoids and four non-overlapping spectral components decadall, interannual, seasonal and intraseasonal) we demonstrate that the quality of the ocean products depends on the considered frequency band. We also discuss the importance of using data-constrained ocean models in future efforts to improve ocean angular momentum estimates.