GNSS RO technique pushes forward the detection of volcanic clouds.
Presenter:
Valeria Cigala
Università degli Studi di Padova
Università degli Studi di Padova, AIRES Pty Ltd, Wegener Center for Climate and Global Change, Institute for Geophysics, Astrophysics, and Meteorology/Institute of Physics, University of Graz, Royal Belgium Institute for Space Aeronomy
Talk
Volcanoes can inject in the atmosphere large amounts of gas and pyroclasts during explosive eruptions. The smaller size of pyroclasts, volcanic ash, and the gas can eventually reach the upper troposphere and lower troposphere and being transported for hundreds of kilometres from the source. They can affect the structure of the atmosphere and pose a severe hazard to, for example, the aviation system. Therefore, to detect volcanic clouds and monitor their dispersal is the subject of much of current research studies.
Several detection models and techniques are available via satellites and ground-based instruments. However, the discrepancies between the different methods lead to detected volcanic cloud altitude with significant uncertainties. For the first time, this study shows the results of an algorithm developed by using the Global Navigation Satellite System (GNSS) radio occultation (RO) technique developed explicitly for high vertical resolution detection of the volcanic cloud altitude. RO profiles are temporally (±12 hours) and spatially (±0.2° in Latitude and Longitude) collocated with the volcanic cloud of volcanic eruptions with a Volcanic Explosivity Index (VEI) of at least 3. The volcanic cloud is detected first on acquisitions from AIRS, IASI and GOME sensors and double checked on backscatter images from CALIOP Lidar.
In the case of the energetic Kasatochi eruption of August 2008, the volcanic cloud altitude detected with the ROs is in good agreement (about 1 km) with the cloud altitude estimations from CALIOP backscatter images. The final goal is to automate the detection of volcanic clouds on RO profile, providing a new high-resolution monitoring tool.
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