Gas, Plume, and Thermal Monitoring

Optimizing satellite resources for the global assessment and mitigation of volcanic hazards—Suggestions from the USGS Powell Center Volcano Remote Sensing Working Group

“…Three distinct categories of sensors exist (table 1): (1) low-spatialresolution but high-temporal-resolution geostationary weather satellites, such as Himawari and Geostationary Operational Environmental Satellite (GOES), which have a spatial resolution of more than 1 kilometer per pixel (km/pixel) and images every few minutes (MIR, TIR); (2) moderate spatial and temporal resolution polar-orbiting sensors such as Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS), which provide several images per day at pixel spacing greater than or equal to 0.375 km/pixel; and (3) high-spatial-resolution but low-temporal-resolution SWIR and TIR systems such, as Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Landsat-8 and -9, and Sentinel-2, which provide images at resolutions of less than or equal to 100 meters per pixel (m/pixel) but have revisit intervals of days to weeks or longer. There are several review articles on thermal remote sensing of volcanoes (Harris and others, 2000;Flynn and others, 2000;Ramsey and Harris, 2013;Ramsey andothers, 2015, 2022;Carn, 2015a;Dehn and Harris, 2015) as well as a textbook (Harris, 2013).…”

“…Although global compilations of SO 2 emissions spanning multiple decades have been assembled, no such database exists for ash (see section 2.1.5). Several review papers describe methods to detect and quantify volcanic gases (for example, Krueger and others, 2000;Realmuto, 2000;Brenot and others, 2014;Carn, 2015a;Prata, Bluth, and others, 2015;Carn and others, 2016;Prata, 2016). The first satellite observations of volcanic outgassing were the unexpected detection of SO 2 from the El Chichón, Mexico, eruption in 1982 by the Total Ozone Mapping Spectrometer (TOMS) ozone sensor (Krueger, 1983).…”

Volcanic Gases

“…Since the late 1960s, degassing associated to erupting volcanoes has been assessed by remote sensing observations (e.g., measurement from distal locations; Carn, 2015). This has allowed the characterisation of large, open-vent gas emissions through volcanic plumes (Figure 1b), and the quantification of volcanic gas fluxes (e.g., mass of gas released per unit time) by deriving integrated gas column amount along the cross section of a plume.…”

“…Scattered ultraviolet (UV) sunlight, measured from ground or aircraft, has been used as the source for measuring SO 2 fluxes from volcanoes using COrrelation SPECtrometers (COSPEC). More recently, the advent of more compact and less power consuming scanning differential optical adsorption spectrometers (DOAS) has revolutionized our ability to make fully automated, continuous gas observations leading to unprecedented long SO 2 flux records of high spatial-time resolution (Galle et al, 2003;Carn, 2015).…”

“…It was in the 1980s that a new era in volcanology opened when the Total Ozone Mapping Spectrometer (TOMS) contributed the first satellite-based measurements of SO 2 emitted by explosive volcanic eruptions (Krueger, 1983). Spaceborne UV spectrometers (e.g., the Ozone Monitoring Instrument, OMI, on NASA's Aura satellite) detects SO 2 emissions from large volcanic eruptions and effectively contribute to monitoring passively degassing volcanoes, particularly those located in remote or unexplored regions (Carn, 2015). The major challenge of satellites remains to extend observations to detection/quantification of other relevant volcanic species that are less abundant (H 2 S, CO) or more difficult to investigate (CO 2 ).…”