The HY-2A calibration microwave radiometer (CMR) water vapor product is validated using ground-based GNSS observations along the coastline and shipborne GNSS observations over the Indian Ocean. The validation result shows that HY-2A CMR PWV agrees well with ground-based GNSS PWV, with 2.67 mm in rms within 100 km and an RMS of 1.57 mm with shipborne GNSS for the distance threshold of 100 km. Ground-based GNSS and shipborne GNSS agree with HY-2A CMR well.

The paper focuses on the analyses of the global occurrence of equatorial plasma bubble events using S4 data that were calculated from GPS radio occultation measurements of the FormoSat-3/COSMIC mission. The advantage in using radio occultation data is that we get information not only on the occurrence and intensity of the equatorial bubble events, but also on the altitude distribution. We analyzed a 10.5-year time series of COSMIC data and demonstrated a strong dependence on the solar cycle.

Nowadays, new GNSS, like European Galileo or Chinese Beidou are available. Some members of the International GNSS Service (IGS) provide multi-GNSS precise satellite orbits, but no final orbit combination exists yet. We developed a new algorithm to combine satellite orbits for all GNSS constellations. Two different strategies were applied. To validate our results we compared our GPS orbits with the official IGS orbits. Our results show that the best strategy applied reached an agreement ~15 mm.

ICGEM is a non-profit scientific service that contributes to any research area in which the use of gravity information is essential. ICGEM offers the largest collection of global gravity field models, interactive calculation and visualisation services and delivers high-quality datasets to researchers and students in geodesy, geophysics, glaciology, hydrology, oceanography, and climatology and most importantly general public. Static, temporal, and topographic gravity field models are available.

The recent dramatic development of multi-GNSS constellations brings great opportunities and potential for more enhanced precise positioning, navigation, timing, and other applications. In this contribution, we develop a numerical weather model (NWM) constrained PPP processing system to improve the multi-GNSS precise positioning. Compared to the standard PPP solution, significant improvements of both convergence time and positioning accuracy are achieved with the NWM-constrained PPP solution.