A Global Survey of Volcanic SO2 Emissions and Heat Flux Measured from Space

Abstract:

Over the past two decades, the availability of satellite measurements of volcanic gas emissions and heat flux has driven the development of new methodologies to improve global-scale volcano monitoring. In this work we aim to explore the correlation between volcanic sulfur dioxide (SO₂) emissions and radiant heat flux (RHF) measurements from NASA’s Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS), respectively, to gain insight into their association with volcanic processes and eruption styles. A strong correlation between SO₂ emissions and RHF is expected in ‘open-vent’ volcanic systems where magma is degassed close to the surface, but a detailed analysis of this linkage and its temporal variation at a range of volcanic systems is currently lacking. Given that several satellites can measure volcanic SO₂ and RHF, improved understanding of their relationship would allow more accurate characterization of volcanic activity using satellite data. The OMI SO₂ emissions data are derived from an existing database (Carn et al., Sci. Rep., 2017), which contains global, passive volcanic SO₂ degassing fluxes (PVF) for ~90-100 active volcanoes in 2005-2019. Volcanoes from the PVF dataset with measurable RHF in MODIS data will be identified using the University of Hawaii’s MODVOLC thermal alert system (http://modis.higp.hawaii.edu/). We are investigating correlations between MODIS RHF data (and integrated radiant energy) and SO₂ emissions on various timescales (seasonal to annual) using statistical methods (e.g., regression analysis, time-series analysis). Our analysis will reveal the covariation of these parameters on different spatial and temporal scales (from individual volcanoes to entire volcanic arcs) and with lava composition or eruptive style (e.g., lava lakes, lava domes). The analysis will also consider possible interferences or geometric constraints on satellite observations (e.g. cloud cover, satellite viewing angles). We hope that this work will advance satellite-based volcano monitoring, particularly where ground-based observations are lacking, and also permit estimation of volcanic SO₂ fluxes prior to the OMI mission (pre-2005) for some volcanic systems.