Brenot, H. ; Biondi, R. ; Nahmani, S. ; Cannavò, F. ; Pottiaux, E. ; Hammouti, M. ; De Pace, A. ; Crespi, M. ; Mazzoni, A. ; Trzcina, E. ; Rohm, W.

Talk presented at IAG Scientific Assembly 2025, Rimini, Italy on 2025-09-04

Abstract: Integrating geodetic remote sensing with multi-satellite observations from polar-orbiting and geostationary sensors for monitoring convective and volcanic clouds Hugues Brenot1, Riccardo Biondi2, Samuel Nahmani3, Flavio Cannavò4, Eric Pottiaux5, Mohammed Hammouti6, Alessandra De Pace7, Mattia Crespi7, Augusto Mazzoni7, Estera Trzcina8 and Rohm Witold8 (1) Royal Belgian Institute for Space Aeronomy (BIRA), Brussels, Belgium. (brenot@aeronomie.be) (2) International Centre for Environmental Monitoring (CIMA), Savona, Italy. (riccardo.biondi@cimafoundation.org) (3) Paris Institute of Earth Physics (IPGP), France. (samuel.nahmani@ign.fr) (4) National Institute of Geophysics and Volcanology – Etna Observatory (INGV-OE), Catania, Italy. (flavio.cannavo@ct.ingv.it) (5) Royal Observatory of Belgium (ROB), Brussels, Belgium. (eric.pottiaux@observatoire.be) (6) Institute of Environmental Geology and Geoengineering of the National Research Council (IGAG-CNR), Italy. (mohammed.hammouti@igag.cnr.it) (7) Sapienza University of Rome, Italy. (alessandramaria.depace@uniroma1.it) (8) Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences (IGiG-WUELS), Poland. (witold.rohm@igig.up.wroc.pl) Climate change affects all regions of Earth's atmosphere, from the equator to the poles, driven primarily by human activities and volcanic eruptions. The rise in severe weather events and hazardous clouds, such as volcanic ash plumes and industrial emissions, poses serious threats to public health and can cause widespread damage. Additionally, both convective storms and volcanic ash clouds present significant risks to aviation safety. In this context, the aim of this work — which is part of the Convective and Volcanic Cloud (CVC) sub-workgroup of the IAG Commission 4 on “Positioning and applications”, section “Atmospheric remote sensing — is to enhance the detection of hazardous atmospheric structures by analysing disruptions in GNSS radio wave signals received by ground stations or polar low Earth orbit (LEO) polar satellites (radio-occultation). Three benchmark campaigns/sites are considered to enhance risk detection, warnings, and mitigation strategies for extreme CVC events. This presentation focusses on severe weather events in the summer of 2021, including flooding in the Benelux region, western Germany, and northeastern France, as well as hailstorms in Poland. It also covers eruptions of two volcanoes: Etna (2015, 2018, and 2021) and Ruang (2024). Results from GNSS techniques regarding the 3D structure and height of convective cells and volcanic ash-laden plumes are obtained by integrating data from other remote sensing methods, including hyperspectral sensors on LEO and multi-spectral sensors on geostationary (GEO) satellites. Detecting and monitoring extreme clouds involves quantifying atmospheric refractivity and delay propagation of radio signal to identify anomalies relative to reference data. Developing tropospheric parameters from multi-GNSS data is crucial for reconstructing 3D structures through tomography and creating diagnostic tools based on slant delay observations, aiming to characterise the vertical profiles of CVCs. A comparison of classical geodetic software outputs with retrievals using a variational technique is also conducted.

Keyword(s): volcanic clouds ; Convective clouds ; perturbation ; radio signal ; neutral