GNSS Orbit and Clock Determination for (Near-)Real-time Occultation Data Processing

The processing of radio-occultation (RO) observations for numerical weather prediction relies on a near-real-time (NRT) orbit and clock determination of the host satellite, which in turn requires knowledge of the GNSS satellite orbit and clock offset information with minimum latency. Recent year have shown continuous advancements in the field of precise orbit determination (POD) for LEO satellites but also for the (near-)real time genration of GNSS satellite orbit and clock products. The presentation describes the currently achieved NRT POD performance and highlights relevant developments that may affect the future processing of RO data. The IGS Real-Time service offering-free-of-charge orbit and clock corrections for GPS (and GLONASS) satellites in real-time is highlighted and the potential for real-time onboard orbit determination and RO processeing is discussed. Special attention is also given to orbit anc clock determiation for emerging new GNSS constellations and the experience gained so far within the IGS Multi-GNSS experiment