4:30 PM - 4:45 PM
[G02-6-01] Establishing an IHRS reference station
The definition of an International Height Reference System (IHRS) and its realization to an International Height Reference Frame (IHRF) is gaining increased importance given the outstanding results offered by the GOCE mission. Additionally, the availability of satellite altimetry data close to the coastline from the Cryosat2 SAR and SARin modes, allow the collocated determination with shipborne gravity of marine gravity anomalies not only for purely marine areas but close to the sea-land boundary as well. Finally, the existence of GOCE-derived Global Geopotential Models (GGMs), historic and current land gravity measurements, GNSS-derived ellipsoidal heights at Continuously Operating Reference Stations (CORS), and first-order levelling data set the field for the proper determination of the Earth's potential on benchmarks (BMs) that will serve as IHRF reference network stations.
The main scope of the current work is to present the theoretical aspects and practical results of determining the Earth's potential Wi at a GNSS reference station that belongs to the EUREF network. To that respect, all available gravity observations within a distance of 210 km around the AUT1 CORS reference station are collected and combined through a remove-compute-restore procedure to determine the residual disturbing potential of that specific BM. The long wavelengths are represented by the GOCE/GRACE GGM GOCO05s/GOCO05c, band-limited to d/o 250, and the high-frequencies by the SRTM 3 arcsec DTM. Least squares collocation (LSC) is used as an optimal predictor while error propagation utilizes the GGM commission error, DTM errors and the a-priori variances of the gravity data. Various configurations of the spatial distribution of the input gravity data are investigated and their influence on the final Wi prediction is outlined. Finally, conclusions on the most rigorous local/satellite/terrain data configuration are drawn along with proposals for the needed improvements and requirements.
The main scope of the current work is to present the theoretical aspects and practical results of determining the Earth's potential Wi at a GNSS reference station that belongs to the EUREF network. To that respect, all available gravity observations within a distance of 210 km around the AUT1 CORS reference station are collected and combined through a remove-compute-restore procedure to determine the residual disturbing potential of that specific BM. The long wavelengths are represented by the GOCE/GRACE GGM GOCO05s/GOCO05c, band-limited to d/o 250, and the high-frequencies by the SRTM 3 arcsec DTM. Least squares collocation (LSC) is used as an optimal predictor while error propagation utilizes the GGM commission error, DTM errors and the a-priori variances of the gravity data. Various configurations of the spatial distribution of the input gravity data are investigated and their influence on the final Wi prediction is outlined. Finally, conclusions on the most rigorous local/satellite/terrain data configuration are drawn along with proposals for the needed improvements and requirements.