Effective Frequencies and Ionosphere Calibration of Legacy S/X Data

Abstract

Over the past, the computation of ionosphere calibrations for legacy S/X band observations and especially the derivation of effective frequencies has undergone various changes. While trying to implement the respective processes in our own software VieVS we encountered differences between our on-the-fly computations and the values stored in vgosDB files. We found that in the transition from native Mark3 databases to vgosDB files in a non-negligible number of sessions, ionospheric corrections have not been migrated with state of the art. IVS Analysis Centers are being made aware that the entries for ionosphere calibrations in vgosDB files are inconsistent over the years as may be the submissions of individual IVS Analysis Centers. A recommendation is given to recompute effective frequencies and ionosphere calibrations always with up to date formulations.