Assessment of GNSS PPP-Based Zenith Tropospheric Delay

Mohamed Abdelazeem,Ahmed El-Rabbany

doi:10.2478/arsa-2020-0012

Mohamed Abdelazeem, Ahmed El-Rabbany

Open Access

https://doi.org/10.2478/arsa-2020-0012

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Abstract

Abstract This study assesses the precision of zenith tropospheric delay (ZTD) obtained through triple-constellation global navigation satellite system (GNSS) precise point positioning (PPP). Various ZTD estimates are obtained as by-products from GPS-only, GPS/Galileo, GPS/BeiDou, and triple-constellation GPS/Galileo/BeiDou PPP solutions. Triple-constellation GNSS observations from a number of globally distributed reference stations are processed over a period of seven days in order to investigate the daily performance of the ZTD estimates. The estimated ZTDs are then validated by comparing them with the International GNSS Service (IGS) tropospheric products and the University of New Brunswick (UNB3m) model counterparts. It is shown that the ZTD estimates agree with the IGS counterparts with a maximum standard deviation (STD) of 2.4 cm. It is also shown that the precision of estimated ZTD from the GPS/Galileo and GPS/Galileo/BeiDou PPP solutions is improved by about 4.5 and 14%, respectively, with respect to the GPS-only PPP solution. Moreover, it is found that the estimated ZTD agrees with the UNB3m model with a maximum STD of 3.1 cm. Furthermore, the GPS/Galileo and GPS/Galileo/BeiDou PPP enhance the precision of the ZTD estimates by about 6.5 and 10%, respectively, in comparison with the GPS-only PPP solution.

Highlights

The troposphere represents the lower part of the Earth’s atmosphere, which extends from the Earth’s surface up to an altitude of approximately 10 km
Our study aims to evaluate the precision of the zenith tropospheric delay (ZTD) estimates using triple-constellation global navigation satellite systems (GNSS) observations, namely GPS, Galileo, and BeiDou
The objective of this paper is to assess the precision of the estimated ZTD using tripleconstellation GNSS observations

Summary

INTRODUCTION

The troposphere represents the lower part of the Earth’s atmosphere, which extends from the Earth’s surface up to an altitude of approximately 10 km. Lu et al (2015) developed a real-time ZTD estimation model using GPS and the BeiDou observations. The estimated ZTDs from the GPS-only, the BeiDou-only the combined GPS/BeiDou solutions were compared with those obtained from the very-long baseline interferometry (VLBI). Pan and Guo (2018) proposed a real-time ZTD estimation model using quad-constellation GNSS observations. The ZTDs were computed through the PPP technique using GNSS observations from various constellations (i.e., GPS-only, GPS/GLONASS, and GPS/GLONASS/Galileo/BDS). For validation purposes, the estimated ZTDs are compared with the international GNSS service (IGS) final tropospheric products and the widely used university of New Brunswick (UNB3m) tropospheric model

ZTD ESTIMATION USING TRIPLE-CONSTELLATION GNSS PPP

TRIPLE-CONSTELLATION GNSS DATA SETS

RESULTS AND ANALYSIS

CONCLUSION