Determination of Zenith Tropospheric Delay (ZTD) Using CORS GNSS Data, 2016 – 2020 In Lampung

GNSS satellites transmit signals in the form of electromagnetic waves to ground-based observation stations (receivers). As these signals pass through the atmosphere - particularly the troposphere - they undergo delays and bending due to differences in atmospheric properties. This results in deviations in signal path length, known as Zenith Tropospheric Delay (ZTD). In positioning applications, ZTD is considered an error that must be minimized. However, in meteorological studies, ZTD serves as valuable information representing atmospheric water vapor content. This study aims to estimate ZTD values using GNSS observation data from CORS stations in the Lampung region. Data was processed using the Precise Point Positioning (PPP) method via an online platform. The results show that the highest ZTD value in 2016 was recorded at the CSBK station on DOY 182 with 2682.8 mm. In 2017, the highest value occurred at the CTCN station on DOY 274 with 2650.2 mm. From 2018 to 2020, the highest ZTD values were recorded at the CKRI station, with 2655.8 mm (DOY 001.18), 2676.4 mm (DOY 001.19), and 2691.0 mm (DOY 091.20), respectively. These findings indicate that ZTD data derived from GNSS observations hold significant potential for supporting local atmospheric studies.