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Measuring gas and aerosol fluxes with multispectral TIR image data: Bridging the gap between ground and satellite scales

Jean-François Smekens 1, Michael S. Ramsey2, James O. Thompson3, Alessandro La Spina4, Claudia Corradino4 and Daniel Williams2.

  • Affiliations: 1 Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA; 2 Department of Earth and Environmental Science, University of Pittsburgh, Pittsburgh, PA, USA; 3 Bureau of Economic Geology, University of Texas, Austin, TX, USA; 4 Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia, Catania, Sicily, IT

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 122

  • Programme No: 3.15.27

  • Theme 3 > Session 15

Abstract

Orbital multispectral IR instruments are used routinely to derive gas and ash fluxes from volcanic eruptions (e.g., ASTER, MODIS, SEVIRI). The same approach remains difficult to implement in ground-based instruments, due to challenges associated with deployment, maintenance and complex viewing geometries. High-resolution IR spectrometers (OP-FTIR) are also routinely used to quantify gases and particulates at the source. However, these instruments are relatively bulky, only sampling plumes in one location, and must be combined with other data sources to constrain flux information. Multispectral IR imagers can offer a comprehensive solution albeit at a lower spectral resolution, providing the spatial and contextual information necessary to calculate fluxes. In this work, we assess the capacity of a new multispectral IR imager to quantify gas emissions from volcanic sources. The MMT-gasCam acquires images in 12 spectral channels between 8 and 12 µm, with a sampling frequency of ~ 1 Hz. We test an iterative forward model algorithm to retrieve SO2and sulfate aerosols using data acquired at three Italian volcanoes with varying levels of activity: Etna, Stromboli and Vulcano. We contrast the results with brightness temperature difference (BTD) methods, similar to those used for satellite retrievals. Although computationally much faster, BTD methods target individual plume components and produce ambiguous results that are difficult to interpret on the complex proximal plumes. Information gathered from multispectral ground-based instruments can help understand the link between source and distal plumes, a key factor to correctly interpret monitoring signals with future higher resolution IR orbital sensors such as SBG.