Anatomy of apparent seasonal variations from GPS‐derived site position time series

Apparent seasonal site position variations are derived from 4.5 years of global continuous GPS time series and are explored through the “peering” approach. Peering is a way to depict the contributions of the comparatively well‐known seasonal sources to garner insight into the relatively poorly known contributors. Contributions from pole tide effects, ocean tide loading, atmospheric loading, nontidal oceanic mass, and groundwater loading are evaluated. Our results show that ∼40% of the power of the observed annual vertical variations in site positions can be explained by the joint contribution of these seasonal surface mass redistributions. After removing these seasonal effects from the observations the…