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- Diamantidis, Periklis, 1988, et al.
(författare)
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Combining VGOS, legacy S/X and GNSS for the determination of UT1
- 2022
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Ingår i: Journal of Geodesy. - : Springer Science and Business Media LLC. - 0949-7714 .- 1432-1394. ; 96:8
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Tidskriftsartikel (refereegranskat)abstract
- We perform a combination on the observation level (COL) between VLBI and co-located GNSS in the context of VLBI intensive sessions. Our approach revolves around an estimation procedure which uses 3 h of GNSS data that uniformly encapsulate the 1-h VLBI data, in order to provide consistent troposphere information. We test this approach on both VGOS and Legacy S/X using the VGOS-B and concurrently observed INT1 sessions. The COL strategy is found to increase the precision by 15 % over both session types and leads to an increase of 65 % in the agreement between the sessions when estimating tropospheric gradients every 3 h. A more frequent estimation of the gradients every 1 h, which can be rigorously pursued with the utilization of multi-GNSS, results in a further convergence of the two session types by 30 %. The COL-aided length-of-day (LOD) products also show a 55 % better agreement to external GNSS-derived LOD. In the light of the increasing precision of broadcast GNSS orbits and clocks, this COL strategy can be used to derive rapid UT1-UTC products.
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| 2. |
- Elgered, Gunnar, 1955, et al.
(författare)
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Comparison of four different GNSS antenna installations using estimated atmospheric gradients and microwave radiometry
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have assessed the quality of four GNSS antenna installations by studying time series of estimated linear horizontal gradients in the signal delay. The stations have different electromagnetic environments. We also examine the consistency of the results by using two different GNSS softwares, GipsyX and c5++, and applying three different elevation cutoff angles: 5◦, 10◦, and 20◦. The estimated gradients are compared to the corresponding ones estimated from microwave radiometer observations acquired during six months (April–September 2021). We have indications that it is an advantage to equip the area below the GNSS antenna with microwave absorbing material. However, the differences are small and more studies are needed to decide if such an investment is reasonable in terms of cost and maintenance.
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