Assessment of the GNSS Data Collected at the Main Continuously Operating Reference Stations (CORS) of the Iraqi Geodetic Network

Abstract

The Continuously Operating Reference Station (CORS) network has several stations that collect and record data from Global Navigation Satellite System (GNSS) constellations. These stations run continuously in an automated manner to collaborate and interact with different users for positioning services. In this study, the collected GNSS data at five CORS sites of the Iraqi Geodetic network was assessed to determine if there were any significant changes in the positions of these stations for a long time. This change gives a clear interpretation of the impact of different geophysical phenomena (e.g. tectonic plate motion) on the stability of positions within time. Therefore, the collected data at ZAXO, ISER, ISBA, ISKU and ISNA stations were analysed for seven years 2015 – 2022 (i.e. from 1st Jan 2015 to 31st Dec 2021). The daily position of each station can be computed from 24-hour recording data at a 30-second rate using GAPS or CSRS free software for Precise Point Positioning (PPP). Thus, 8806 observation daily files were used. The processed data was represented as a time series in Easting, Northing and Up coordinates for each station to analyse the trend of movement in these stations. It was found that the change in both Easting and Northing coordinates has a linear trend, which agrees with the general trend of tectonic motion in this part of the world. The mean yearly change was within 22-27 mm. On the other hand, the change in the Up coordinate with time had a fluctuated change over time "wave behaviour" or exhibited periodic variations.

Keywords

• CORS
• Iraqi geodetic network
• GNSS data
• Precise Point Positioning (PPP)