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G2.5 | Measurement biases and systematic errors in modern space geodetic observation techniques
Measurement biases and systematic errors in modern space geodetic observation techniques
Convener: Mathis Bloßfeld | Co-conveners: Jan Kodet, Eva Hackmann
Modern space geodetic observation techniques benefit from the technical development during the last decades. In nearly all techniques, groundbreaking achievements led to an increase of the measurement accuracy of several orders of magnitude. Nowadays, the major limiting factor for a reliable interpretation of the observed quantities (and consequently a resilient monitoring of global change phenomena) are measurement biases (time, range, frequency, etc.), systematic errors caused by the measurement electronics, as well as imperfect models to account for signal delays within the Earth atmosphere. These systematic errors limit the accuracy of determining the terrestrial reference frame (TRF). Recently, the research unit (RU) 'TIME' (Clock Metrology: A Novel Approach to TIME in Geodesy) was established in Germany to develop strategies to realize and take advantage of TIME as a novel and independent observable in space geodesy at the Geodetic Observatory Wettzell (GOW). The major focus of the RU is to investigate the possibilities of a geodetic fundamental station like GOW equipped with a common clock and a common target for all space geodetic observation techniques in order to accomplish the goals of the Global Geodetic Observing System (GGOS), namely 1 mm accuracy for the positions of the TRF together with a stability of 1 mm per decade. The research conducted there will aid identifying, quantifying and compensating for systematic errors in modern space geodetic observation techniques. Furthermore, the integration of optical clocks in Geodesy provides novel opportunities and new challenges, while satellite missions like ACES provide the means to transfer time at unprecedented levels of accuracy.

This session welcomes contributions from various fields of geodetic research on the key words time in geodesy (as closure technique), delay-compensated time (and frequency) distribution, time transfer, systematic errors in measurement electronics, optical clocks in geodesy and quantum sensing for geodetic applications, and measurement biases. Presentations and posters can also focus on existing and further developed strategies to overcome systematics in the space geodetic observation techniques such as long-term mean range biases in SLR observations, gravitational deformation of VLBI antennas, South-Atlantic-Anomaly corrections for DORIS observations, GNSS phase center variations, local tie discrepancies in global TRF solutions, etc.