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277807.0 [No comment] 24.07.2006 14:51 Released

ID: 277807.0, MPI für Kernphysik / Physics of Atmospheric Molecular Processes
Determination of polar stratospheric cloud particle refractive indices by use of in situ optical measurements and T-matrix calculations
Authors:Scarchilli, C.; Adriani, A.; Cairo, F.; Donfrancesco, G.; Buontempo, C.; Snels, M.; Moriconi, ML.; Deshler, T.; Larsen, N.; Luo, BP.; Mauersberger, Konrad; Schreiner, Jochen; Ovarlez, J.; Rosen, J.
Date of Publication (YYYY-MM-DD):2005-06-01
Title of Journal:Applied Optics
Issue / Number:16
Start Page:3302
End Page:3311
Copyright:© 2005 Optical Society of America
Review Status:not specified
Audience:Experts Only
Abstract / Description:A new algorithm to infer structural parameters such as refractive index and asphericity of cloud particles has been developed by use of in situ observations taken by a laser backscattersonde and an optical particle counter during balloon stratospheric flights. All three main particles, liquid, ice, and a no-ice solid (NAT, nitric acid trihydrate) of polar stratospheric clouds, were observed during two winter flights performed from Kiruna, Sweden. The technique is based on use of the T-matrix code developed for aspherical particles to calculate the backscattering coefficient and particle depolarizing properties on the basis of size distribution and concentration measurements. The results of the calculations are compared with observations to estimated refractive indices and particle asphericity. The method has also been used in cases when the liquid and solid phases coexist with comparable influence on the optical behavior of the cloud to estimate refractive indices. The main results prove that the index of refraction for NAT particles is in the range of 1.37-1.45 at 532 nm. Such particles would be slightly prolate spheroids. The calculated refractive indices for liquid and ice particles are 1.51-1.55 and 1.31-1.33, respectively. The results for solid particles confirm previous measurements taken in Antarctica during 1992 and obtained by a comparison of lidar and optical particle counter data.
Free Keywords:Atmospheric and ocean optics, Aerosols, Index measurements, Scattering measurements, Scattering, particles
External Publication Status:published
Document Type:Article
Affiliations:MPI für Kernphysik/Group K. Mauersberger/Ozone Isotope Research (K. Mauersberger)