During April-May 2010 the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft flew 12 flights targeting volcanic ash clouds around the UK. The aircraft observed ash layers between altitudes of 2-8 km with peak mass concentrations typically between 200-2000 μg/m 3, as estimated from a Cloud and Aerosol Spectrometer (CAS). A peak value of 2000-5000 μg/m 3 was observed over Scotland on 14 May 2010, although with considerable uncertainty due to the possible contamination by ice. Aerosol size distributions within ash clouds showed a fine mode (0.1-0.6 μm) associated with sulphuric acid and/or sulphate, and a coarse mode (0.6-35 μm) associated with ash. The ash mass was dominated by particles in the size range 1-10 μm (volume-equivalent diameter), with a peak typically around 3-5 μm. Electron-microscope images and scattering patterns from the SID-2H (Small Ice Detector) probe showed the highly irregular shape of the ash particles. Ash clouds were also accompanied by elevated levels of SO 2 (10-100 ppbv), strong aerosol scattering (50-500 × 10 -6 m -1), and low Ångstrom exponents (-0.5 to 0.4) from the 3-wavelength nephelometer. Coarse-mode mass specific aerosol extinction coefficients (k ext), based on the CAS size distribution varied from 0.45-1.06 m 2 /g. A representative value of 0.6 m 2 /g is suggested for distal ash clouds (∼1000 km downwind) from this eruption. Copyright 2012 by the American Geophysical Union.
CITATION STYLE
Johnson, B., Turnbull, K., Brown, P., Burgess, R., Dorsey, J., Baran, A. J., … Rosenberg, P. (2012). In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010. Journal of Geophysical Research Atmospheres, 117(8). https://doi.org/10.1029/2011JD016760
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