About this Research Topic
This Research Topic focuses on meteorological applications based on GNSS and SAR interferometry (InSAR). GNSS and SAR interferometry are two space geodesy techniques that are contributing to the study of neutral atmosphere. GNSS Meteorology is an established field of research and applications to map the tropospheric Precipitable Water Vapor (PWV), also thanks to the availability of regional and global ground-based networks. Even if the number of GNSS receivers has greatly increased, at least in a few geographical areas, GNSS measurements of PWV are characterized by a high temporal sampling but a relatively poor spatial sampling.
For this reason an increasing interest has been shown in the scientific community on the recent applications of SAR interferometry to the mapping of PWV also thanks to the shortening of revisiting times. Many of these applications have been conducted in the C-band due to free access to data regularly acquired by the Sentinel-1 mission but also L-band data have a great potential for PWV mapping. The spatial resolution of PWV maps is by far larger than that of GNSS measurements even if the temporal sampling is of a few days, also depending on the specific SAR mission. Geostationary SAR concepts have been proposed that could increase the temporal sampling of SAR PWV maps at the cost of a poorer spatial resolution.
GNSS radio occultation can provide measurement of water vapor in the atmosphere also above the sea where it is not easy to measurements as GNSS receivers are not available and SAR interferometry cannot provide information due to the lack of interferometric coherence.
Besides measuring of the total water vapor techniques, the GNSS signal can also be used to estimate the 3D distribution of atmosphere refractivity as done by the GNSS tomography technique.
Experiments were carried out to assimilate water vapor products into high resolution Numerical Weather Models to better model atmosphere thermodynamics at small scale, such in convective phenomena, and to provide most accurate forecasts of heavy rainfalls and flash floods. This opened new perspectives for the updating of the current assimilation procedures and the development of new tools for the visualization of results. The possibility to densify GNSS permanent networks, also thanks to the more and more performing low-cost GNSS receivers, the large amount of Sentinel-1 data and the launch of new L and C-band SAR missions in the next decade is opening new perspectives for an operational GNSS and SAR meteorology.
We welcome, but not limit, contributions on the subjects below:
• Methodologies to the spatial and temporal distribution of water vapor in the neutral atmosphere using space geodesy techniques such as GNSS, GNSS tomography, SAR interferometry, radio occultation, etc.
• Studies on synergies between different GNSS systems and new spaceborne SAR missions to study the neutral atmosphere;
• Assimilation of GNSS and SAR products in high resolution Numerical Weather Prediction and climate reanalysis models: methodologies and case studies.
• Study of propagation delay into the ionosphere and impact on the accuracy of GNSS and InSAR meteorology products.
Keywords: Synthetic Aperture Radar (SAR) interferometry, Global Navigation Satellite System (GNSS), Numerical Weather Prediction (NWP) model, Data assimilation, Extreme weather
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