Mount Etna Plume Height and Eruption Style from MISR

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Figure 1: MISR stereo heights for the ash-dominated plume on 30 December 2002.

Figure 2: 29 Sept. 2006 – MISR retrieved small spherical particles, indicating a sulfate/water-dominated plume.

Figure 3: MISR stereo heights for the sulfate/water-dominated plume on 25 Nov. 2006.

The strength of volcanic eruptions is related to the fraction of volcanic ash in the plume, compared to water and sulfate particles.  The elevation of the plume above the surface is also an indication of strength, as well as a key factor in predicting how long the particles will reside in the atmosphere, how far they will travel, and the magnitude of their environmental impact.  Data from the NASA Earth Observing System’s Multi-angle Imaging SpectroRadiometer (MISR) can monitor both these quantities, globally.  Plume injection height is derived from MISR stereo observations, and in this study, is applied to Mount Etna eruptions for six years between 2000 and 2008, and tested against ground-based triangulations.  The two-dimensional maps of height produced from MISR observations compare well in the tests, and provide much more extensive plume height information than is available from any other source. 

The new and most important contribution of Scollo et al. (2012) is a demonstration of MISR’s ability to distinguish volcanic plumes dominated by ash from those dominated by sulfate and water particles.  Volcanic ash is identified in the MISR aerosol retrievals as large, non-spherical, somewhat dark particles, whereas sulfate and water particles are small-medium, spherical, non-absorbing particles.  For the nine cases during the study period for which coincident MISR and ground-based observations of Etna plume particle properties were made, MISR correctly identified the plume eruptive style based on particle type. MISR has acquired more than 12 years of global observations, which are now being mined for volcanic plume eruptive style as well as injection height, greatly expanding our knowledge of volcano environmental impacts, globally. And more detailed analysis of particle property variations along volcanic plumes, using MISR data, is part of continuing work (Kahn et al., 2012).

References:

  1. Scollo, S., R.A. Kahn, D.L. Nelson, M. Coltelli, D.J. Diner, M.J. Garay, and V.J. Realmuto, 2012. MISR observations of Etna volcanic plumes. J. Geophys. Res., in press.

  2. Kahn, R.A., J.A. Limbacher, B.J. Gaitley, and M.J. Garay, 2012.  Eyjafjalljökull Volcano Ash Plume Particle Type Characterization from Space-Based Multi-angle Imaging. Atmosph. Chem. Phys., in preparation.