[G01-P] Poster

[G01-P-07] Assimilation of satellite altimetry, gravity, leveling and GOCE data for the definition of the Saudi Arabia National Reference Frame (SANVRF)

^○George S. Vergos¹, Rossen Grebenitcharsky², Dimitrios A. Natsiopoulos¹, Othman Al-Kherayef², Bandar Al-Musulmani² (1.GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece, 2.General Directorate of Geodesy, General Commission for Survey, Kingdom of Saudi Arabia)

The definition, realization and availability of a common, nationwide and modernized Vertical Reference System (VRS) and Vertical Reference Frame (VRF) is of utmost importance, since it sets the base of all geodetic, surveying and engineering applications. A rigorous VRS/VRF realization supports regional scale projects and possible ties to an International Height Reference System (IHRS). The Kingdom of Saudi Arabia (KSA) has taken unique initiatives for the establishment and re-measurement of its entire geodetic infrastructure. Within that frame, a) high-accuracy spirit leveling measurements have been carried out to form the new National Vertical Network (NVN), b) absolute and relative gravity surveys have been conducted to form the new National Gravity Network (NGN), and c) 11 Tide Gauge (TG) stations have been established to form the National TG Network (NTGN). On the other hand, the current KSA VRS is outdated, exhibits significant tilts and biases, while local VRFs are in place as well. To provide KSA with a modern VRS/VRF the aforementioned data have been used for the definition and realization of a new height system. Given that the only missing information for such an assimilated processing were the ellipsoidal heights at the TG benchmarks (BMs), a 30-year satellite altimetry time-series has been constructed using all available past and current missions.
The current work focuses on the presentation of all processing steps for the construction of the altimetry-derived sea level record for each TG station, the estimation of the TG Mean Sea Level and its trends, and the derivation of TG ellipsoidal heights. Then, the use of GOCE-based Global Geopotential Models is presented, while the estimation of geopotential numbers for all TGs is outlined. Finally, unconstrained and constrained Least Squares (LS) adjustments of the entire TG and Levelling network are carried out, estimating the output errors and the distortions introduced to the final network.