Thick ash poured from Iceland’s Eyjafjallajökull Volcano when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this image on April 17, 2010. The ash in this image is at two different altitudes. A concentrated plume rises over a more diffuse cloud of ash, casting a dark shadow on the ash below. The volcano had been emitting ash in puffs that reached between 16,000 and 24,000 feet, according to the Icelandic Met Office. The higher plume seen here is likely from a more explosive event.

Now some new research on this eruption leads to a conclusion that volcano aerosols may be underestimated. Apparently they find that there’s a secondary nucleation particle mechanism. They say:

…we report the first observation of nucleation and new secondary particle formation events in a volcanic plume.

Essentially, they analyzed how many secondary particles this ash generated as it reacted with the atmospheric chemistry of the atmosphere. They found that particles created from the eruptions were mostly composed of sulfuric acid, but as a consequence of the atmospheric reactions, especially at lower than previously considered altitudes, they grew over time, multiplying the effect. This new paper was in the PNAS early edition this week.

Abstract:

Observations of nucleation of new particles in a volcanic plume

Julien Boulona,1, Karine Sellegria, Maxime Hervoa, and Paolo Lajb + Author Affiliations

aLaboratoire de Météorologie Physique, Observatoire de Physique du Globe de Clermont Ferrand, Centre National de la Recheche Scientifique, Unité Mixte de Recherche 6016, Université Blaise Pascal, 63177 Aubière, France; and

bLaboratoire de Glaciologie et Géophysique de l’Environnement, Observatoire des Sciences de l’Univers de Grenoble, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5183, Université Joseph Frourier, BP 53-38041 Grenoble Cedex 9, France Edited by Mark H. Thiemens, University of California, La Jolla, CA, and approved June 21, 2011 (received for review March 29, 2011)

Abstract Volcanic eruptions caused major weather and climatic changes on timescales ranging from hours to centuries in the past. Volcanic particles are injected in the atmosphere both as primary particles rapidly deposited due to their large sizes on time scales of minutes to a few weeks in the troposphere, and secondary particles mainly derived from the oxidation of sulfur dioxide. These particles are responsible for the atmospheric cooling observed at both regional and global scales following large volcanic eruptions. However, large condensational sinks due to preexisting particles within the plume, and unknown nucleation mechanisms under these circumstances make the assumption of new secondary particle formation still uncertain because the phenomenon has never been observed in a volcanic plume. In this work, we report the first observation of nucleation and new secondary particle formation events in a volcanic plume. These measurements were performed at the puy de Dôme atmospheric research station in central France during the Eyjafjallajokull volcano eruption in Spring 2010. We show that the nucleation is indeed linked to exceptionally high concentrations of sulfuric acid and present an unusual high particle formation rate. In addition we demonstrate that the binary H 2 SO 4 – H 2 O nucleation scheme, as it is usually considered in modeling studies, underestimates by 7 to 8 orders of magnitude the observed particle formation rate and, therefore, should not be applied in tropospheric conditions. These results may help to revisit all past simulations of the impact of volcanic eruptions on climate. h/t to reader “Scarlet Pumpernickel”.

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