Assessment of Parameters Describing the Signal Delay in the Neutral Atmosphere Derived from VGOS Observations

Paper in proceeding, 2023

We use the VGOS session VR2101 to assess parameters describing the signal delay in the neutral atmosphere. VGOS results are compared to corresponding results derived from co-located GNSS stations for all sites, and additionally to results from a ground-based microwave radiometer for the Onsala Space Observatory. For the first time all three independent techniques can be compared with the same high temporal resolution of 5 min. Zenith total delays from VGOS and GNSS reveal correlation coefficients larger than 0.9 for all but one of the participating sites. Corresponding offsets are between 1–8 mm and root mean square differences are between 4–14 mm. Horizontal gradients from VGOS and GNSS have correlation coefficients between 0.2–0.5 for the east components and 0.4–0.7 for the north components. Corresponding offsets are sub-millimeter, and root mean square differences are on the order of 0.5–2.2 mm. The comparisons for the Onsala site of VGOS and GNSS w.r.t. microwave radiometer show correlation coefficients larger than 0.96 for the zenith total delays with offsets on the order of 7–11 mm and root mean square differences of 9–12 mm. Horizontal gradients show correlation coefficients of about 0.2 for the east components and about 0.5 for the north components. The corresponding offsets are between 0.6–1.8 mm and the root mean square differences are 0.9–1.3 mm.