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The troposphere consists of dry air and water vapor, delaying the GNSS signal by about 2.4 m in the zenith direction. The water vapor only causes an error of about 0.2 m in distance measurement, but it is challenging to model and overcome. From 2003 the International GNSS Service (IGS) started to provide the new product of zenith path delay (ZPD) with an accuracy of 1.5-5 mm. However, we found an error in these products up to 30 mm at epochs between 2 days due to the day boundary effect and an average of 16mm RMS for nine days. Our research shows that for reducing the impact, the most critical factor is selecting the initial value for the ZPD, followed by satellite orbit/clock and, finally, the station coordinate values. By choosing an appropriate initial value for ZPD and employing a 3 days orbit/clock, the ZPD error due to the day boundary effect can be reduced to negligible. Meanwhile, the change in the station coordinate value in cm level does not impact the effect.

Item Type:	Refereed Article
Keywords:	zenith path delay, TZD, day boundary effect, GNSS, PPP
Research Division:	Earth Sciences
Research Group:	Geophysics
Research Field:	Geodesy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Coleman, R (Professor Richard Coleman)
ID Code:	147150
Year Published:	2021
Web of Science® Times Cited:	1
Deposited By:	Directorate
Deposited On:	2021-10-14
Last Modified:	2021-12-13
Downloads:	10 View Download Statistics