Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids |
| |
Authors: | Timo Nousiainen Michael Kahnert |
| |
Institution: | a Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, 105 S. Gregory St., Urbana, IL 61801, USA b Department of Physical Sciences, University of Helsinki, P.O. Box 64, FIN-00014 University of Helsinki, Finland c Swedish Meteorological and Hydrological Institute, Folkborgsvägen 1, S-601 76 Norrköping, Sweden d Department of Molecular and Laser Physics, University of Nijmegen, Toernooiveld 1, 6525 ED NIJMEGEN, The Netherlands |
| |
Abstract: | The use of simplified particle shapes for modeling scattering by irregularly shaped mineral-dust particles is studied using polyhedral prisms and spheroids as model particles. Simulated phase matrices averaged over shape and size distributions at wavelength 633 nm are compared with a laboratory-measured phase matrix of feldspar particles with known size distribution with effective radius of . When an equi-probable shape distribution is assumed, prisms and oblate spheroids agree with measurements to a similar degree, whereas prolate spheroids perform markedly better. Both spheroids and prisms perform much better than spheres. When an automatic fitting method is applied for finding optimal shape distributions, it is found that the most elongated spheroids are most important for good fits, whereas nearly-spherical spheroids are generally of very little importance. The phase matrices for the different polyhedral prisms, on the other hand, are found to be similar, thus their shape-averaged phase matrices are insensitive to the shape distribution assumed. For spheroids, a simple parameterization for the shape distribution, where weights increase with increasing departure from spherical shape, is proposed and tested. This parameterization improves the fit of most phase matrix elements attained with an equi-probable shape distribution, and it performs particularly well for reproducing the measured phase function. |
| |
Keywords: | Mineral aerosol Light scattering Non-sphericity T-matrix Shape distribution |
本文献已被 ScienceDirect 等数据库收录! |
|