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| Titel |
Volcanic ash infrared signature: porous non-spherical ash particle shapes compared to homogeneous spherical ash particles |
| VerfasserIn |
A. Kylling, M. Kahnert, H. Lindqvist, T. Nousiainen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 4 ; Nr. 7, no. 4 (2014-04-04), S.919-929 |
| Datensatznummer |
250115691
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| Publikation (Nr.) |
 copernicus.org/amt-7-919-2014.pdf |
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| Zusammenfassung |
| The reverse absorption technique is often used to detect volcanic ash clouds
from thermal infrared satellite measurements. From these measurements
effective particle radius and mass loading may be estimated using radiative
transfer modelling. The radiative transfer modelling usually assumes that the
ash particles are spherical. We calculated thermal infrared optical
properties of highly irregular and porous ash particles and compared these
with mass- and volume-equivalent spherical models. Furthermore, brightness
temperatures pertinent to satellite observing geometry were calculated for
the different ash particle shapes. Non-spherical shapes and volume-equivalent
spheres were found to produce a detectable ash signal for larger particle
sizes than mass-equivalent spheres. The assumption of mass-equivalent spheres
for ash mass loading estimates was found to underestimate mass loading
compared to morphologically complex inhomogeneous ash particles. The
underestimate increases with the mass loading. For an ash cloud recorded
during the Eyjafjallajökull 2010 eruption, the mass-equivalent spheres
underestimate the total mass of the ash cloud by approximately 30%
compared to the morphologically complex inhomogeneous particles. |
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