TIDAL OBSERVATION USING GNSS-INTERFEROMETRIC REFLECTOMETRY TECHNIQUE

• Main Author: Nanda Putra Hartoto, Dwi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/79183
• Institution: Institut Teknologi Bandung

The observations of tidal sea-level variations have long been conducted in Indonesia for various purposes, including safeguarding national borders, coastal engineering, and disaster monitoring. These observations have traditionally relied on sensor-based instruments commonly known as tide gauges. These tide gauges, often permanently installed alongside GNSS antennas at various coastal stations, are susceptible to temperature and pressure fluctuations, which can lead to inaccuracies in tidal data readings. Moreover, long-term use of tide gauges can be influenced by ground surface movements, which serve as the reference for tidal measurements. Advancements in hardware technology, supported by sophisticated software, have introduced GNSS (Global Navigation Satellite System) for observational purposes in the vicinity of GNSS station locations. Tidal sea-level data can now be obtained by utilizing satellite signals that are reflected (multipath) from the sea surface. This technique is commonly referred to as GNSS-Interferometric Reflectometry (GNSS-IR). Senior researchers who have long been developing algorithms incorporated into GNSS-IR software have achieved centimeter-level precision, nearly equivalent to traditional tide gauge sensors. The objective of this research is to obtain tidal sea-level data in Indonesia, particularly at the Paleleh and Bengkunat stations, using quality control procedures tailored to the specific conditions of the observation sites. These quality control measures are employed to numerically and physically eliminate biases. Additionally, the inclusion of multiple satellite segments enhances temporal resolution. The satellite segments used in this study comprise GPS, GLONASS, and GALILEO satellites. The research results indicate that the precision of the GNSS-IR reflector at the Paleleh station is superior to that at the Bengkunat station, demonstrating excellent accuracy compared to tide gauge sensors, as evidenced by a Root Mean Square Error (RMSE) of ~8 centimeters. Correlation tests also reveal strong relationships at each station, with a 98% correlation at the Paleleh station and a 95% correlation at Bengkunat. Based on these findings, it is anticipated that tidal observations using GNSS-IR technology can become a primary alternative for analyzing tidal information.