The impact of higher‐order ionospheric effects on estimated tropospheric parameters in Precise Point Positioning

Abstract

AbstractThe impact of higher‐order ionospheric effects on the estimated station coordinates and clocks in Global Navigation Satellite System (GNSS) Precise Point Positioning (PPP) is well documented in literature. Simulation studies reveal that higher‐order ionospheric effects have a significant impact on the estimated tropospheric parameters as well. In particular, the tropospheric north‐gradient component is most affected for low‐latitude and midlatitude stations around noon. In a practical example we select a few hundred stations randomly distributed over the globe, in March 2012 (medium solar activity), and apply/do not apply ionospheric corrections in PPP. We compare the two sets of tropospheric parameters (ionospheric corrections applied/not applied) and find an overall good agreement with the prediction from the simulation study. The comparison of the tropospheric parameters with the tropospheric parameters derived from the ERA‐Interim global atmospheric reanalysis shows that ionospheric corrections must be consistently applied in PPP and the orbit and clock generation. The inconsistent application results in an artificial station displacement which is accompanied by an artificial “tilting” of the troposphere. This finding is relevant in particular for those who consider advanced GNSS tropospheric products for meteorological studies.