EGVAP geodetic partnersBackgroundTraditional meteorological observing systems are owned by the meteorological institutions, and (some of) the data are shared internationally among member institutes. The main expertise on the systems is found within the meteorological organisations. For ground based GNSS measurements the situation is very different and much more complicated. A small fraction of the GNSS stations providing the raw measurements are owned by meteorological institutes, but the majority is owned by mapping agencies, geodectic research institutes, and private companies. The situtation differs from country to country, both concerning number of site owners and availability of the data. Further, the processing of the raw data to the meteorologically interesting zenith total delays (ZTD) is done by a number of processing centres, each of which is processing the raw data from a multitude of GNSS sites belonging to different organisations. To enable collection of GNSS data and processing into delays in near real time close collaboration between both site owners and data processing centres and the meteorological organisations is absolutely vital. Because the majority of the deployed GNSS networks are national it has in EGVAP been decided that it is the responsibility of the EGVAP member of each member country to arrange a collaboration with the national site owners. Both concerning access to the data in NRT and concerning eventual expansions of the network. The EGVAP team and in particular the operational liason group can provide guidance in this process. Part of the GNSS measurements come from international networks, used, e.g., for determination of the GNSS reference frame. The EGVAP team is in contact with those in order to make arrangements enabling access to data and data processing in near real time. E-GVAP make available certain observational data and NWP model data that can be used to validate GNSS processing results, and likely in the future be used to improve GNSS data processing, in terms of better control of the atmospheric effects upon positioning, and faster processing. |
The EUREF Permanent Network.