Exploring different ITRF2020 seasonals for a reprocessing campaign

Before switching to ITRF2020 as an operational frame, the JPL IGS analysis center needs to reprocess GNSS data from 1992 to present. Unlike an IGS reprocessing campaign, in which contributions from many groups are combined as input to each ITRF, this reprocessing is an independent effort to provide users of the GipsyX software and others with a consistent set of orbit and clock products in the current ITRF2020 frame. One of the main innovations in the ITRF2020 frame over the previous ITRF2014 frame is the estimation of site-specific seasonals and a global seasonal signal of the motion of the Earth's center of mass (CM). Before committing to a reprocessing strategy, we explore the effect of different choices of seasonal: no seasonals, seasonals with CM annual motion, and seasonals without CM motion. We assess the effect of this choice on different users and products of our solution: station positions in our network solution, station positions obtained by PPP users, and positions of satellites with highly sensitive OD (e.g. altimetry missions). We also explore options for our users to remove the annual CM motion from PPP time series for applications where that motion might be considered an undesirable signal.