{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T22:10:04Z","timestamp":1778278204930,"version":"3.51.4"},"reference-count":55,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2019,9,20]],"date-time":"2019-09-20T00:00:00Z","timestamp":1568937600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"STARS@Unipd","award":["NA"],"award-info":[{"award-number":["NA"]}]},{"DOI":"10.13039\/501100002428","name":"Austrian Science Fund","doi-asserted-by":"publisher","award":["P27724-NBL (VERTICLIM)"],"award-info":[{"award-number":["P27724-NBL (VERTICLIM)"]}],"id":[{"id":"10.13039\/501100002428","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The products of explosive volcanic eruptions, in particular, volcanic ash, can pose a severe hazard to, for example, international aviation. Detecting volcanic clouds and monitoring their dispersal is hence, the subject of intensive current research. However, the discrepancies between the different available methods lead to detected cloud altitude with significant uncertainties. Here we show the results of an algorithm developed explicitly for high vertical resolution detection of volcanic cloud altitude by using the Global Navigation Satellite System radio occultation (RO) observations. Analyzing the energetic Kasatochi eruption of August 2008 in a case study, we find the volcanic cloud altitudes detected with RO in good agreement (within ~1 km) with cloud altitude estimations from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar backscatter images in the 4 h range between RO and CALIOP acquisitions. The tracking by combined RO and imaging of the volcanic cloud evolution during the weeks after the eruption indicates a promising potential for operational global cloud altitude monitoring.<\/jats:p>","DOI":"10.3390\/rs11192199","type":"journal-article","created":{"date-parts":[[2019,9,20]],"date-time":"2019-09-20T10:48:14Z","timestamp":1568976494000},"page":"2199","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["GNSS Radio Occultation Advances the Monitoring of Volcanic Clouds: The Case of the 2008 Kasatochi Eruption"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2410-136X","authenticated-orcid":false,"given":"Valeria","family":"Cigala","sequence":"first","affiliation":[{"name":"Dipartimento di Geoscienze, Universit\u00e0 degli Studi di Padova, 35131 Padua, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3062-0326","authenticated-orcid":false,"given":"Riccardo","family":"Biondi","sequence":"additional","affiliation":[{"name":"Dipartimento di Geoscienze, Universit\u00e0 degli Studi di Padova, 35131 Padua, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9285-9565","authenticated-orcid":false,"given":"Alfredo J.","family":"Prata","sequence":"additional","affiliation":[{"name":"AIRES Pty Ltd., Mt Eliza, VIC 3930, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1201-3303","authenticated-orcid":false,"given":"Andrea K.","family":"Steiner","sequence":"additional","affiliation":[{"name":"Wegener Center for Climate and Global Change (WEGC), University of Graz, 8010 Graz, Austria"},{"name":"Institute for Geophysics, Astrophysics, and Meteorology\/Institute of Physics, University of Graz, 8010 Graz, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gottfried","family":"Kirchengast","sequence":"additional","affiliation":[{"name":"Wegener Center for Climate and Global Change (WEGC), University of Graz, 8010 Graz, Austria"},{"name":"Institute for Geophysics, Astrophysics, and Meteorology\/Institute of Physics, University of Graz, 8010 Graz, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hugues","family":"Brenot","sequence":"additional","affiliation":[{"name":"Royal Belgium Institute for Space Aeronomy, 1180 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"D00L10","DOI":"10.1029\/2009JD013621","article-title":"Characterization of the 2008 Kasatochi and Okmok eruptions using remote infrasound arrays","volume":"115","author":"Fee","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_2","unstructured":"Sennert, S.K. (2008). Weekly Volcanic Activity Report, 6\u201312 August 2008, Smithsonian Institution and US Geological Survey. Report on Kasatochi (USA)."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"D00L21","DOI":"10.1029\/2009JD013634","article-title":"Volcanic ash and SO2 in the 2008 Kasatochi eruption: Retrievals comparison from different IR satellite sensors","volume":"115","author":"Corradini","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"D00L02","DOI":"10.1029\/2009JD012786","article-title":"Detection of volcanic SO2, ash, and H2SO4 using the Infrared Atmospheric Sounding Interferometer (IASI)","volume":"115","author":"Karagulian","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"4343","DOI":"10.5194\/acp-16-4343-2016","article-title":"The vertical distribution of volcanic SO2 plumes measured by IASI","volume":"16","author":"Carboni","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.jvolgeores.2016.01.002","article-title":"Multi-decadal satellite measurements of global volcanic degassing","volume":"311","author":"Carn","year":"2016","journal-title":"J. Volcanol. Geotherm. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"D00L19","DOI":"10.1029\/2010JD013868","article-title":"Aviation response to a widely dispersed volcanic ash and gas cloud from the August 2008 eruption of Kasatochi, Alaska, USA","volume":"115","author":"Guffanti","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"D00L12","DOI":"10.1029\/2009JD013039","article-title":"Lidar measurements of the Kasatochi aerosol plume in August and September 2008 in Ny-\u00c5lesund, Spitsbergen","volume":"115","author":"Hoffmann","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"D00L15","DOI":"10.1029\/2010JD013987","article-title":"Infrasound observations of the 2008 explosive eruptions of Okmok and Kasatochi volcanoes, Alaska","volume":"115","author":"Arnoult","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"D00L20","DOI":"10.1029\/2010JD013984","article-title":"Dispersion and lifetime of the SO2 cloud from the August 2008 Kasatochi eruption","volume":"115","author":"Krotkov","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"D00L13","DOI":"10.1029\/2009JD013650","article-title":"Lidar observations of Kasatochi volcano aerosols in the troposphere and stratosphere","volume":"115","author":"Bitar","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"D00L04","DOI":"10.1029\/2009JD013472","article-title":"Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008\u20132009","volume":"115","author":"Mattis","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"D00L18","DOI":"10.1029\/2009JD013556","article-title":"Ash and sulfur dioxide in the 2008 eruptions of Okmok and Kasatochi: Insights from high spectral resolution satellite measurements","volume":"115","author":"Prata","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"D00L16","DOI":"10.1029\/2009JD013286","article-title":"Remote sensing and inverse transport modeling of the Kasatochi eruption sulfur dioxide cloud","volume":"115","author":"Kristiansen","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"D00L17","DOI":"10.1029\/2010JD013890","article-title":"Airborne stratospheric ITCIMS measurements of SO2, HCl, and HNO3 in the aged plume of volcano Kasatochi","volume":"115","author":"Jurkat","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"D00L03","DOI":"10.1029\/2009JD013274","article-title":"Evolution of the stratospheric aerosol enhancement following the eruptions of Okmok and Kasatochi: Odin-OSIRIS measurements","volume":"115","author":"Bourassa","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"D00L05","DOI":"10.1029\/2009JD013525","article-title":"Negligible climatic effects from the 2008 Okmok and Kasatochi volcanic eruptions","volume":"115","author":"Kravitz","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.rse.2004.02.004","article-title":"An evaluation of VC detection techniques during recent significant eruptions in the western \u201cRing of Fire\u201d","volume":"91","author":"Tupper","year":"2004","journal-title":"Remote Sens. Environ."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"9459","DOI":"10.5194\/acp-12-9459-2012","article-title":"Eyjafjallj\u00f6kull Volcano Plume Particle-Type Characterization from Space-Based Multi-angle Imaging","volume":"12","author":"Kahn","year":"2012","journal-title":"Atmos. Chem. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/j.rse.2016.01.024","article-title":"Volcanic Plume Elevation Model and its velocity derived from Landsat 8","volume":"176","author":"Raucoules","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1175\/BAMS-89-3-313","article-title":"The COSMIC\/Formosat\/3 mission: Early results","volume":"89","author":"Anthes","year":"2008","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_22","first-page":"L03808","article-title":"Immediate impact of the Mt Chaiten eruption on atmosphere from FORMOSAT-3\/COSMIC constellation","volume":"36","author":"Wang","year":"2009","journal-title":"Geophys. Res. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.jvolgeores.2012.08.018","article-title":"Atmospheric temperature changes by volcanic eruptions: GPS radio occultation observations in the 2010 Icelandic and 2011 Chilean cases","volume":"245","author":"Okazaki","year":"2012","journal-title":"J. Volcanol. Geotherm. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"23429","DOI":"10.1029\/97JD01569","article-title":"Observing Earth\u2019s atmosphere with radio occultation measurements using the Global Positioning System","volume":"102","author":"Kursinski","year":"1997","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5309","DOI":"10.5194\/acp-12-5309-2012","article-title":"Thermal structure of intense convective clouds derived from GPS radio occultations","volume":"12","author":"Biondi","year":"2012","journal-title":"Atmos. Chem. Phys."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"5181","DOI":"10.5194\/acp-15-5181-2015","article-title":"Characterization of thermal structure and conditions for overshooting of tropical and extratropical cyclones with GPS radio occultation","volume":"15","author":"Biondi","year":"2015","journal-title":"Atmos. Chem. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2707","DOI":"10.1016\/j.asr.2017.06.039","article-title":"Supporting the detection and monitoring of VCs: A promising new application of Global Navigation Satellite System radio occultation","volume":"60","author":"Biondi","year":"2017","journal-title":"Adv. Space Res."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"44095","DOI":"10.1038\/srep44095","article-title":"A decade of global volcanic SO2 emissions measured from space","volume":"7","author":"Carn","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Prata, A.J., and Bernardo, C. (2007). Retrieval of volcanic SO2 column abundance from Atmospheric Infrared Sounder data. J. Geophys. Res. Atmos., 112.","DOI":"10.1029\/2006JD007955"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"6041","DOI":"10.5194\/acp-9-6041-2009","article-title":"Monitoring of atmospheric composition using the thermal infrared IASI\/MetOp sounder","volume":"9","author":"Clerbaux","year":"2009","journal-title":"Atmos. Chem. Phys."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"581","DOI":"10.5194\/amt-5-581-2012","article-title":"Retrieval of sulphur dioxide from the infrared atmospheric sounding interferometer (IASI)","volume":"5","author":"Clarisse","year":"2012","journal-title":"Atmos. Meas. Tech."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2195","DOI":"10.5194\/acp-13-2195-2013","article-title":"A unified approach to infrared aerosol remote sensing and type specification","volume":"13","author":"Clarisse","year":"2013","journal-title":"Atmos. Chem. Phys."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1099","DOI":"10.5194\/nhess-14-1099-2014","article-title":"Support to Aviation Control Service (SACS): An online service for near-real-time satellite monitoring of volcanic plumes","volume":"14","author":"Brenot","year":"2014","journal-title":"Nat. Hazards Earth Syst. Sci."},{"key":"ref_34","unstructured":"Munro, R., Eisinger, M., Anderson, C., Callies, J., Corpaccioli, E., Lang, R., Lefebvre, A., Livschitz, Y., and P\u00e9rez Albi\u00f1ana, A. (2006, January 12\u201316). GOME-2 on MetOp. Proceedings of the 2006 EUMETSAT Meteorological Satellite Conference, Helsinki, Finland."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"D00U19","DOI":"10.1029\/2011JD016718","article-title":"Volcanic SO2, BrO and plume height estimations using GOME-2 satellite measurements during the eruption of Eyjafjallaj\u00f6kull in May 2010","volume":"117","author":"Rix","year":"2012","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Platt, U., and Stutz, J. (2008). Differential absorption spectroscopy. Differential Optical Absorption Spectroscopy, Springer.","DOI":"10.1007\/978-3-540-75776-4_6"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2310","DOI":"10.1175\/2009JTECHA1281.1","article-title":"Overview of the CALIPSO mission and CALIOP data processing algorithms","volume":"26","author":"Winker","year":"2009","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_38","first-page":"RS6004","article-title":"Comparative analysis of radio occultation processing approaches based on Fourier integral operators","volume":"39","author":"Gorbunov","year":"2004","journal-title":"Radio Sci."},{"key":"ref_39","unstructured":"Schw\u00e4rz, M., Kirchengast, G., Scherllin-Pirscher, B., Schwarz, J., Ladst\u00e4dter, F., and Angerer, B. (2016). Multi-Mission Validation by Satellite Radio Occultation Extension Project\u2014Final Report, Wegener Center, University of Graz. Tech. Rep. for ESAESRIN 01\/2016."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"4845","DOI":"10.5194\/amt-10-4845-2017","article-title":"Quality aspects of the Wegener Center multi-satellite GPS radio occultation record OPSv5.6","volume":"10","author":"Angerer","year":"2017","journal-title":"Atmos. Meas. Tech."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1175\/JTECH-D-18-0105.1","article-title":"Representation of Vertical Atmospheric Structures by Radio Occultation Observations in the Upper Troposphere and Lower Stratosphere: Comparison to High-Resolution Radiosonde Profiles","volume":"36","author":"Zeng","year":"2019","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3263","DOI":"10.1029\/2001GL013117","article-title":"Atmosphere sounding by GPS radio occultation: First results from CHAMP","volume":"28","author":"Wickert","year":"2001","journal-title":"Geophys. Res. Lett."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"D06109","DOI":"10.1029\/2003JD003909","article-title":"CHAMP and SAC-C atmospheric occultation results and intercomparisons","volume":"109","author":"Hajj","year":"2004","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"L13806","DOI":"10.1029\/2005GL023109","article-title":"GPS radio occultation with GRACE: Atmospheric profiling utilizing the zero difference technique","volume":"32","author":"Beyerle","year":"2005","journal-title":"Geophys. Res. Lett."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Steiner, A.K., Pirscher, B., Foelsche, U., and Kirchengast, G. (2009). GPS radio occultation with CHAMP, GRACE-A, SAC-C, TerraSAR-X, and FORMOSAT-3\/COSMIC: Brief review of results from GFZ. New Horizons in Occultation Research: Studies in Atmosphere and Climate, Springer.","DOI":"10.1007\/978-3-642-00321-9"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"18631875","DOI":"10.1175\/2008BAMS2399.1","article-title":"Prospects of the EPS GRAS mission for operational atmospheric applications","volume":"89","author":"Luntama","year":"2008","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1875","DOI":"10.5194\/amt-4-1875-2011","article-title":"Empirical analysis and modeling of errors of atmospheric profiles from GPS radio occultation","volume":"4","author":"Steiner","year":"2011","journal-title":"Atmos. Meas. Tech."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1595","DOI":"10.1002\/2016JD025902","article-title":"The power of vertical geolocation of atmospheric profiles from GNSS radio occultation","volume":"122","author":"Steiner","year":"2017","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"2007","DOI":"10.5194\/amt-4-2007-2011","article-title":"Refractivity and temperature climate records from multiple radio occultation satellites consistent within 0.05%","volume":"4","author":"Foelsche","year":"2011","journal-title":"Atmos. Meas. Tech."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"RS0D24","DOI":"10.1029\/2010RS004614","article-title":"GPS radio occultation for climate monitoring and change detection","volume":"46","author":"Steiner","year":"2011","journal-title":"Radio Sci."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"D00L07","DOI":"10.1029\/2009JD013628","article-title":"Aerosol layers from the 2008 eruptions of Mount Okmok and Mount Kasatochi: In situ upper troposphere and lower stratosphere measurements of sulfate and organics over Europe","volume":"115","author":"Schmale","year":"2010","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_52","unstructured":"Civil Aviation Authority (CAA) (2019, July 07). Guidance Regarding Flight Operations in the Vicinity of Volcanic Ash. Available online: http:\/\/publicapps.caa.co.uk\/modalapplication.aspx?appid=11&catid=1&id=6464&mode=detail&pagetype=65."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1016\/j.jvolgeores.2009.02.015","article-title":"Reducing discrepancies in ground and satellite-observed eruption heights","volume":"186","author":"Tupper","year":"2009","journal-title":"J. Volcanol. Geotherm. Res."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1175\/WAF974.1","article-title":"Facing the Challenges of the International Airways Volcano Watch: The 2004\/05 Eruptions of Manam, Papua New Guinea","volume":"22","author":"Tupper","year":"2007","journal-title":"Weather Forecast."},{"key":"ref_55","unstructured":"Zehner, C. (2010, January 26\u201327). Monitoring volcanic ash from space. Proceedings of the ESA-EUMETSAT Workshop on the 14 April to 23 May 2010 Eruption at the Eyjafjallaj\u00f6kull Volcano, South Iceland, Frascati, Italy. ESA-Publication STM-280."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/19\/2199\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:22:28Z","timestamp":1760188948000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/19\/2199"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,9,20]]},"references-count":55,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2019,10]]}},"alternative-id":["rs11192199"],"URL":"https:\/\/doi.org\/10.3390\/rs11192199","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,9,20]]}}}