C-Band Dual-Polarization Observations of a Massive Volcanic Eruption in South America

LUCIANO VIDAL; STEPHEN NESBITT; PAOLA SALIO; SOLEDAD OSORES; CAMILA FARIAS; ANDRÉS RODRIGUEZ; JUAN SERRA; GIORGIO CARANTI

Conferencia; 37th Conference on Radar Meteorology; 2015

Several volcanic eruptions worldwide have been observed by ground-based weather radars but mostof these observations were performed by single polarization radars. Dual polarization technologyproduce additional data fields which can provide valuable information on the structure andcomposition of an eruption column and ash cloud and can be used to determine the ash volume,total mass and height of eruption clouds.In the evening on 22 April 2015 at 21:04UTC, Calbuco volcano had the first eruption after morethan 50 years of being dormant, producing a 15 km ash cloud. Seven hours later, a massive secondexplosion occurred on 23 April 2015 at 04:00 UTC producing a 20 km ash cloud that penetrate thetropopause and injected a lot of ash into the stratosphere. Calbuco is a stratovolcano in southernChile at 41.326 S - 72.614W with an altitude of 2003m amsl. The eruption of Calbuco was the firstvolcanic eruption detected by weather radar in South America and in particular with the firstdomestically-produced Argentinian weather radar called RMA0 located in Bariloche (Rio Negroprovince). It is a Doppler Dual Polarization radar at C-band manufactured by INVAP S.E. as a partof the new radar network for Argentina.The aim of this study is to present analysis of the time evolution of the structure of the volcanicplume using polarimetric variables (e.g., horizontal reflectivity, differential reflectivity, andcorrelation coefficient) in order to explore the potential of this new data set in the analysis aboutstructure and composition of this particular eruption column and subsequent ash cloud. T-matrixsimulations will be used to develop a hydrometeor classification for ash, low density ice-ash,mixed-phase regions, and ice clouds to quantify the time evolution of the volcanic plume.Comparisons with lightning network data will be used to examine links between mixed-phase clouddevelopment and cloud-to-ground lightning activity.