51. Applying tropospheric ties in GNSS and vlbi integrated solution: Impact of deterministic and stochastic uncertainty
- Author
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Wang, Jungang, Glaser, Susanne, Balidakis, Kyriakos, Ge, Maorong, Heinkelmann, Robert, and Schuh, Harald
- Abstract
For microwave-based space geodetic techniques, co-located instruments within a few hundred meters are considered to share the same troposphere, and thus intra-/inter-technique tropospheric ties can be applied to improve the multi-technique integrated solution. The concept of applying tropospheric ties assumes that tropospheric parameters from each technique represent the true tropospheric state, i.e., (1) there should be no technique-related systematic bias, and (2) the technique-specific stochastic noise that leaks into atmospheric delay estimates should be minimized. However, this is usually not the case in reality, as the modeling and parameter estimation in the analysis of space geodetic techniques naturally contain systematic and stochastic uncertainty. For example, the multi-path effect and antenna phase center variation (PCV) error could introduce systematic biases in Global Navigation Satellite Systems (GNSS) tropospheric parameters, and the limitation of observation geometry in Very Long Baseline Interferometry (VLBI) could bias the horizontal gradients. Therefore, it is critical to identify and handle the systematic biases, and properly handle the stochastic part. In this study, we demonstrate that tropospheric parameter biases could be large, e.g., up to 5 mm in zenith total delay (ZTD). Ignoring systematic biases distorts the ground network, especially the VLBI network. For example, the systematic bias in ZTD shifts the network scale, and the bias in horizontal gradients rotates the network and deteriorates earth orientation parameters (EOP). We demonstrate that the GNSS and VLBI integrated solution can be improved after properly handling the tropospheric ties., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)
- Published
- 2023