Recent Activities on Tristan da Cunha Island: Geodetic Installations, Local Tie Measurements and their Analysis

• Main Authors: Teferle, Felix Norman, Hunegnaw, Addisu, Backes, Dietmar, Hibbert, Angela, Williams, Simon D. P., Woodworth, Philip L., Pugh, Jeffrey P.
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: Global Navigation Satellite System; Tide Gauge; Sea Level; Terrestrial Reference Frame; DORIS; Geodetic Tie Measurement; Least Squares Adjustment; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; South Atlantic Ocean
• Online Access: https://orbilu.uni.lu/handle/10993/39979; https://orbilu.uni.lu/bitstream/10993/39979/1/IUGG2019_Teferle.pdf

During 2017 a team from the University of Luxembourg and the National Oceanography Centre, Liverpool, established a permanent Global Navigation Satellite System (GNSS) station and two new tide gauges on Tristan da Cunha Island in the South Atlantic Ocean. These installations were funded through various projects at both collaborating institutions under the umbrella of the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group and the Global Geodetic Observing System (GGOS) focus area on Sea Level Change, Variability and Forecasting. While this was the first scientific installation of a GNSS station on the main island within the Tristan da Cunha archipelago, IGS station GOUG, located on Gough Island which lies 412 km to the south, has been in operation since 1998. Unfortunately GOUG was decommissioned in 2018. Sea level observations on Tristan da Cunha have a longer history than GNSS with various tide gauges having been in operation since 1984. Tristan da Cunha also hosts a Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) station which was established in 2012 after a previous installation was upgraded and moved to the current site. The antenna TCTA is located on the concrete monument of the previous DORIS antenna. Furthermore, in order for future International Terrestrial Reference Frame (ITRF) computations to fully benefit from the proximity of the sensors, the geodetic ties between the respective antennas (and reference markers in case of the tide gauges) need to be determined at the millimeter level using various terrestrial surveying methods and a local benchmark network. This contribution provides details of the activities on Tristan da Cunha including the installations, the established benchmark network, the terrestrial surveys of the geodetic ties and the analysis of these measurements in order to geometrically link the GNSS and DORIS antennas to each other as well as to the tide gauges. R-AGR-0376 - IRP15 - SGSL (20150501-20170430) - TEFERLE Felix ...