Investigation of the effect of tropospheric mapping functions for different station heights and latitudes on PPP

Global Navigation Satellite Systems (GNSS) are used for different geodetic applications such as monitoring deformations and determining plate velocities. Precise positions of stations are needed for such studies. GNSS error sources should be modelled or eliminated to achieve precise coordinates. Some error sources (e.g., receiver and satellite clock errors) can be eliminated by differencing techniques in relative point positioning. However, in precise point positioning (PPP) these errors should be modelled since the technique uses un-differenced and ionosphere-free combinations. Tropospheric signal delay, one of the atmospheric error sources of GNSS, does not depend on the signal frequency; hence, it should be modelled. This delay is modelled in zenith direction, although it occurs along the signal path. This relation is provided with tropospheric mapping functions (MFs). In this study, the effects of MFs for different station heights and latitudes have been investigated. The datasets of 294 continuously operating reference stations were processed with Jet Propulsion Laboratory’s GipsyX v1.2 software. Moreover, the datasets were subdivided into non-overlapping periods between 2 and 24 h to examine the effects of MFs on different session durations.

 

Keywords: GPS, PPP, Troposphere, Mapping Functions, GipsyX v1.2