5:45 PM - 6:00 PM
[G06-2-06] Tropospheric ties for inter-technique comparisons and combinations
Tropospheric parameters are necessarily part of the adjustment process within space geodetic high-precision geodetic processing when using GNSS, DORIS or VLBI data. The intra-/inter-technique comparisons of tropospheric parameters, resulting as by-products of the analyses, provide a useful feedback for the evaluation of the state-of-the-art models and strategies in the reprocessing. The development of combining space geodetic techniques at an observation level suggests external computation of tropospheric ties in order to estimate a single tropospheric correction for two or more collocated stations of different techniques.
The tropospheric ties are optimally separated into two components - zenith dry and wet delays. Several models have been used in the past for calculating tropospheric ties for inter-technique comparison of tropospheric parameters. Recently, we have developed a new method particularly improving vertical scaling of the wet component. Different strategies require different external meteorological data or other specific tropospheric parameters fitted specifically for vertical scaling. The tropospheric ties may be calculated using actual numerical weather data field. Both the accuracy and the simplicity of calculating tropospheric ties will play a key role in a practical implementation of tropospheric ties in future inter-technique comparison and combination activities.
We evaluated different strategies for calculating or approximating tropospheric ties within two basic scenarios: a) using numerical weather reanalysis data fields (ERA-Interim) for an assessment of optimal strategy for the vertical scaling of dry and wet tropospheric components independently, b) assessing the impact of tropospheric ties in comparison of GNSS and radiosonde tropospheric parameters, and c) evaluating tropospheric ties specifically for GNSS, VLBI and selected DORIS collocated stations in order to assess the impact of tropospheric ties in inter-technique comparison.
The tropospheric ties are optimally separated into two components - zenith dry and wet delays. Several models have been used in the past for calculating tropospheric ties for inter-technique comparison of tropospheric parameters. Recently, we have developed a new method particularly improving vertical scaling of the wet component. Different strategies require different external meteorological data or other specific tropospheric parameters fitted specifically for vertical scaling. The tropospheric ties may be calculated using actual numerical weather data field. Both the accuracy and the simplicity of calculating tropospheric ties will play a key role in a practical implementation of tropospheric ties in future inter-technique comparison and combination activities.
We evaluated different strategies for calculating or approximating tropospheric ties within two basic scenarios: a) using numerical weather reanalysis data fields (ERA-Interim) for an assessment of optimal strategy for the vertical scaling of dry and wet tropospheric components independently, b) assessing the impact of tropospheric ties in comparison of GNSS and radiosonde tropospheric parameters, and c) evaluating tropospheric ties specifically for GNSS, VLBI and selected DORIS collocated stations in order to assess the impact of tropospheric ties in inter-technique comparison.