The effects of higher order ionosphere on GNSS tropospheric parameters estimation

In order to study the influence of the high-order ionosphere on the Global Navigation Satellite System (GNSS) tropospheric parameter estimation eight MGEX (Multi GNSS Experience) tracking stations in the Asia Pacific region were selected during the quiet and active periods of solar activity The influence of high-order ionosphere delay on tropospheric parameter estimation in Beidou-2 Navigation Satellite System (BDS-2), Beidou-3 Navigation Satellite System (BDS-3), Global Positioning System (GPS), Global Navigation Satellite System (GLONASS) and Galileo is analyzed through GAMIT10.71 The experimental results show that during the quiet period of solar activity, the maximum influence of high-order ionosphere delay on Galileo’s zenith total delay (ZTD), precipitable water (PW) and north south gradient (${{NS}}_{\text{grad}}$) is 7.70 mm, 1.26 mm and 6.77 mm respectively; The maximum effect of high-order ionosphere delay on the tropospheric east west gradient (${{EW}}_{\text{grad}}$) of GLONASS is 9.30 mm during the active solar period, high-order ionosphere has greater influence on the tropospheric parameter estimation of GNSS among them, the maximum impact of high-order ionosphere delay on the tropospheric ZTD and PW of BDS-2 is 21.30 mm and 3.49 mm respectively; The maximum influence of high-order ionosphere delay on the tropospheric ${{NS}}_{\text{grad}}$ of Galileo is 19.87 mm; The maximum effect of high-order ionosphere delay on tropospheric ${{EW}}_{\text{grad}}$ of GLONASS is 21.21 mm The experimental results further show that high-order ionosphere has little influence on the tropospheric PW estimation of GNSS; ZTD, ${{NS}}_{\text{grad}}$ and ${{EW}}_{\text{grad}}$ have greater influence high-order ionosphere delay has little effect on BDS-3 and GPS tropospheric parameter estimation; Galileo, BDS-2 and GLONASS have greater influence