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UP: Fachverband Umweltphysik
UP 1: Atmosphere - Trace Gases
UP 1.2: Talk
Tuesday, March 8, 2016, 10:45–11:00, H41
Variations of the BrO/SO2 molar ratios during the 2015 Cotopaxi eruption — •F. Dinger1,2, S. Arellano3, J. Battaglia4, N. Bobrowski2,5, B. Galle3, S. Hernandez6, S. Hidalgo6, C. Hörmann1, P. Lübcke2, U. Platt2, M. Ruiz6, S. Warnach2, and T. Wagner1,2 — 1MPIC, Mainz, Germany — 2IUP, University of Heidelberg, Germany — 3Chalmers University of Technology, Gothenburg, Sweden — 4LMV, Université Blaise Pascal-CNRS-IRD, France — 5University of Mainz, Germany — 6IGEPN, Quito, Ecuador
Cotopaxi volcano is located 50 km south of Quito, the capital of Ecuador. After almost 140 years of relative quiescence, increasing activity is observed in seismicity and gas emissions since May 2015. Since 2009 Cotopaxi volcano is part of the Network for Observation of Volcanic and Atmospheric Change (NOVAC) which regularly monitors the SO2 emissions of more than 30 volcanoes using scanning UV-spectrometers. The interpretation of SO2 emissions can be improved by additionally recording halogen/sulphur emission ratios. Recently, it has been shown that spectra from NOVAC instruments can also be used to retrieve the BrO/SO2 molar ratio by applying Differential Optical Absorption Spectroscopy (DOAS). We apply DOAS to analyse the plume composition of Cotopaxi volcano and will present time series of the BrO/SO2 molar ratios as monitored by the ground-based NOVAC instruments since March 2015. Prior to the phreatic explosions in August 2015 the BrO signal was below the detection limit. Soon after the explosions the BrO/SO2 molar ratio was low as 1·10−5, but during September-December 2015 this ratio varies between 3−11·10−5.