An Evaluation of Tropospheric Delay on GNSS Observations

Abstract

The Global Navigation Satellite System (GNSS) is used to nd point locations in latitude, longitude, and altitude which are involved among the satellites and receivers through electromagnetic signals. Due to the refraction of the electromagnetic signals, the signals are delayed than the actual propagation time. In this study, the e ect of tropospheric delay on GNSS observations is considered by single-point observation on a primary control point of the Sri Lanka Datum 99 network. The study aims to investigate the total tropospheric delay of GNSS observations a ected at di erent times of the day without considering dry and wet components of the delay. The 24 hours of dual-frequency row data were collected and processed separately on the morning, afternoon, and evening observations using Leica Geo O ce 8.4 software applying Hop eld, Simpli ed Hop eld, and Saastamoinen models to correct the tropospheric delay. Then the purpose was to identify the variation of GNSS observations a ected at di erent times of the day due to the tropospheric delay, by determining the best tropospheric model which can be used to minimize tropospheric delay, and by de ning the best time for getting GNSS observations. The Saastamoinen model shows the minimum variation towards the original values of the A166 primary control point. According to this study, morning was the best time for collecting data for GNSS purposes.