The tropospheric delay is a serious error source for positioning using Global Navigation
Satellite Systems (GNSS). Since the scientific applications of GNSS positioning such as crustal
deformation studies and earthquakes prediction require high accuracy in positioning, analysis of
tropospheric delay calculation is necessary to improve GNSS positioning accuracy.
In this study data from ground based GNSS receivers are used to evaluate effect of the tropospheric
delay in position determination accuracy. These data are also used to study the tropospheric
delay characteristics. The collected GNSS data are for the year 2013, taken from 8 stations from
Egypt Permanent GNSS Network (EPGN) and 13 IGS stations. The GNSS data were processed
using advanced GNSS software called Bernese V 5.0.
The results show that the RMS of the coordinates is better in case of making estimation for the
troposphere ZWD and bad in case of ignoring the troposphere. Also there is a correlation between
the troposphere and the height component. The troposphere ZWD values have daily, temporal and
spatial variation, depending on time in the day, day in the year, geographic location of the station
and how near it to water. The ZWD values also go upward from the start to the end of the year, and
also it shows high correlation with the water vapor content in the troposphere.

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