Impact of ZTD Estimation and Tropospheric Gradients on Kinematic PPP Accuracy in the Amazon and Southern Regions of Brazil

The study investigated the influence of tropospheric gradients on the accuracy of Precise Point Positioning (PPP), using data from Brazilian Network for Continuous Monitoring of the GNSS Systems (RBMC) in the Amazon and southern regions of Brazil. The research was conducted due to the need to better understand how tropospheric gradients affect the accuracy of kinematic PPP. Understanding these effects is crucial to improving the accuracy of Global Navigation Satellite System (GNSS) positioning, especially in regions with variable atmospheric conditions. The study used RBMC data and tropospheric delay modeling based on Numerical Weather Prediction (PNT) data. The results showed significant improvements in the planimetric accuracy of kinematic PPP with the inclusion of tropospheric gradients. The improvements were observed on the order of millimeters, with increases of up to 3% in horizontal accuracy and 7% in vertical accuracy. The analysis also revealed that estimating tropospheric gradients was more significant in the vertical component and regions with higher humidity tropospheric scenarios. It was concluded that including tropospheric gradients is crucial to improving the accuracy of kinematic PPP, especially in the Amazon region, where tropospheric scenarios are more humid. Additionally, estimating tropospheric gradients was considered as or even more significant in planimetric accuracy than using a Mapping Function based on PNT data. This research highlights the importance of considering tropospheric gradients in GNSS positioning and provides valuable insights for future studies and practical applications in the field of geodesy and satellite navigation.