The Evolution of Icelandic Volcano Emissions, as Observed From Space in the Era of NASA's Earth Observing System (EOS)

Abstract

Volcanoes are natural phenomena that have global environmental impacts. Satellite remote sensing can help classify volcanic eruptions and track the dispersion of emissions. We assess multiple volcanic eruptions in Iceland (Eyjafjallajökull 2010, Grímsvötn 2011, and Holuhraun 2014-2015), using space-borne observations to infer information about the geological dynamics of each volcano and the properties and evolution of plume particles. We derive qualitative constraints on plume particle size, shape, and light-absorption characteristics from Multiangle Imaging SpectroRadiometer (MISR) space-borne imagery. With the MISR Research Algorithm (RA), we distinguish sulfate/water-dominated volcanic plumes from Holuhraun and ash-dominated plumes from Eyjafjallajökull and Grímsvötn, and even identify subtler changes in ash particle size and light-absorption within plumes. Additionally, plume heights are retrieved geometrically from MISR. These are combined with surface thermal anomalies from the MODerate resolution Imaging Spectroradiometer (MODIS) and SO 2 concentrations derived from the Ozone Monitoring Instrument (OMI) to synthesize eruption remote-sensing chronologies. Signals related to differences in particle properties are identified and linked to evolving magma composition at Eyjafjallajökull. The results illustrate the potential to distinguish qualitative differences in eruptive magma composition based on particle light absorption and plume profile from remote-sensing. For the sulfate-rich Holuhraun plumes, the influence of aerosol hygroscopic growth during transport is inferred from such data. Three processes appear to dominate plume evolution in Iceland: downwind aerosol formation, particle hydration, and particle deposition. This work demonstrates enhanced MISR capabilities and, more generally, remote-sensing analysis that can be applied globally, especially where suborbital volcano observations are limited or entirely absent.

Wildfire Smoke Particle Properties and Evolution, From Space-Based Multi-Angle Imaging II: The Williams Flats Fire during the FIREX-AQ Campaign

“…Similarly, constant AOD accompanied by increasing REPS downwind might indicate particle aggregation, whereas constant or increasing AOD accompanied by decreasing REPS may suggest the formation of secondary aerosols. These and other patterns have been observed with MISR in volcanic plumes (e.g., [47,48]).…”

“…With MINX, the user manually defines the plume source, plume extent, and wind direction in the MINX imagery to retrieve heights and winds locally. MINX has been used in a number of studies, including but not limited to retrieving heights and winds for volcano, wildfire, and dust plumes [35,[39][40][41][42][43][44][45][46][47][48][49][50]. Under good conditions, MINX plume height estimates are accurate within +/−0.5 km or better.…”

“…For each 1.1 km MISR pixel, the RA calculates AOD values for each particle component to create a best-guess mixture of the aerosol plume composition, such that the simulated top-of-atmosphere (TOA) reflectances best match those observed in the MISR multi-angle, multi-spectral measurements. This method has already been used for global aerosol typing [48] and for characterizing particle type in volcanic and wildfire plumes [29,43,[46][47][48].…”

“…As discussed subsequently, these particle properties are, for the most part, neatly distinctive between the four plume regions. It is important to reiterate that, when considering specific particle types (e.g., black carbon, brown carbon, soil/dust, non-absorbing aerosols), the MISR-retrieved aerosol properties represent the optical equivalent of the true smoke particle mixture, which is not necessarily a mixture of the specific components retrieved from among those prescribed by the RA climatology [35,47,48,54]. Note that the missing retrievals in the RA results are pixels located above the river, as the version of the RA used in this study is geared for land observations only (future versions will include an over-water component).…”

“…As aircraft measurements sample a single elevation, this mechanism cannot be directly validated in situ. However, the differences between the satellite and aircraft size distributions can provide insight into how particles may be distributed within the atmospheric column (e.g., [48]). Mechanism (3) can be validated from the available in situ data via the changing oxidation state, BC mass, and SSA downwind.…”