Analysis of the interrelation between the daily coordinates of GNSS stations in the Antarctic region and modelled values of non-tidal atmospheric loading

The study examines the influence of tropospheric parameters on the results of GNSS measurements at continuous operating reference stations (CORSs) in the polar conditions of the Antarctic region, which is characterised by abrupt changes in atmospheric pressure and distinctive tropospheric dynamics. The aim of this work is to quantitatively assess the extent to which non-tidal atmospheric loading (NTAL) is manifested in the daily coordinate time series of GNSS stations, and to determine the spatial extent of this effect within the available GNSS data. The study is based on daily coordinate time series of stations in the Antarctic region obtained from the Nevada Geodetic Laboratory (NGL) portal in .tenv3 format, together with global gridded models of non-tidal atmospheric loading from ESMGFZ (Earth System Modelling Group of GeoForschungsZentrum Potsdam) covering the period from 2016 to 2024. At the first stage of the study, the selection of Antarctic stations from the NGL repository was automated and the completeness of their observations was assessed, which made it possible to compile a representative set of stations for year-by-year analysis. Then, for each station, modelled NTAL displacements in the East, North and Up directions (parameters duEW, duNS, duV) were interpolated from its coordinates. Since the coordinate time series contain a trend (long-term variations) and seasonal components, a detrending procedure was applied to isolate the residual signal, after which the residuals of the vertical component (Up) were compared with the modelled duV values. As a result, it was established that for a significant proportion of Antarctic stations a persistent positive correlation is observed between the vertical component residuals and the modelled atmospheric loading, whereas for the horizontal components (East, North) this relationship is substantially weaker. For a number of stations (in particular GMEZ), the correlation in individual years exceeds 0.60, which indicates a noticeable contribution of atmospheric loading to the "noise" component of the daily coordinates. It has also been shown that for most stations the maximum similarity between the series is achieved with no time lag (day-to-day), which is consistent with the expected rapid elastic response of the Earth's crust to variations in atmospheric mass. The obtained results may serve as a practical basis for identifying stations where accounting for NTAL is critical, and for further improving the reliability of geodynamic interpretations under polar conditions.