Title Single ice crystal measurements during nucleation experiments with the depolarization detector IODE
Author Nicolet, M.; Stetzer, O.; Lüönd, F.; Möhler, O.; Lohmann, U.
Author Affil Nicolet, M., Eidgenössiche Technische Hochschule Zürich, Institut für Atmosphäre und Klima, Zurich, Switzerland. Other: Forschungszentrum Karlsruhe, Germany
Source Atmospheric Chemistry and Physics, 10(2), p.313-325, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Part of special issue no. 139, ICIS-2007, edited by Vali, G., Cziczo, D., and Koop, T., http://www.atmos-chem- phys.net/special_issue139.html; published in Atmospheric Chemistry and Physics Discussions: 16 December 2008, http://www.atmos-chem-phys- discuss.net/8/20965/2008/acpd-8-20965- 2008.html ; accessed in May, 2011. 32 refs. GeoRef Acc. No: 310113
Index Terms aerosols; albedo; climatic change; clouds (meteorology); condensation; crystals; experimentation; ice; ice crystals; liquid phases; measurement; particles; solid phases; algorithms; climate change; climate forcing; clouds; experimental studies; Ice Optical DEpolarizatio detector; laboratory studies; liquid phase; polarization; solid phase
Abstract In order to determine the efficiency of different aerosol particles to nucleate ice, an Ice Optical DEpolarization detector (IODE) was developed to distinguish between water droplets and ice crystals in ice nucleation chambers. A laser beam polarized linearly (power: 50 mW, wavelength: 407 nm) is directed through the chamber. The scattered light intensity from particles is measured at a scattering angle of #1V=175° in both polarization components (parallel and perpendicular). The ratio between the perpendicular intensity over the total one yields the depolarization ratio delta . Single particle detection is possible, using a peak detection algorithm. For high particle concentrations, a real-time signal averaging method can also be run simultaneously. The IODE detector was used in connection with the Zurich ice nucleation chamber during the ICIS 2007 workshop where ice nucleation experiments were performed with several aerosol types. In presence of ice crystals, a depolarization ratio could be measured on a particle-by-particle basis. Mean values of delta ranged from 0.24 to 0.37 and agree well with theoretical calculations.
URL http://www.atmos-chem-phys.net/10/313/2010/acp-10-313-2010.pdf
Publication Type journal article
Record ID 65006740