title: Mid-infrared extinction spectra and optical constants of supercooled water droplets.
abstract: Complex refractive indices of supercooled liquid water have been retrieved at 269, 258, 252, and 238 K in the 4500-1100 cm(-1) wavenumber regime from series of infrared extinction spectra of micron-sized water droplets. The spectra collection was recorded during expansion experiments in the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. A Mie inversion technique was applied to derive the low-temperature refractive index data sets by iteratively adjusting the room-temperature optical constants of liquid water until obtaining the best agreement between measured and calculated infrared spectra of the supercooled water droplets. The new optical constants, revealing significant temperature-induced spectral variations in comparison with the room-temperature refractive indices, proved to be in good agreement with data sets obtained in a recent study. A detailed analysis was performed to elaborate potential inaccuracies in the retrieval results when deriving optical constants from particle extinction spectra using an iterative procedure.
authors.affiliation: Forschungszentrum Karlsruhe, Institute of Meteorology and Climate Research (IMK-AAF), Karlsruhe, Germany. Robert.Wagner@imk.fzk.de
authors.forename: Robert
authors.initials: R
authors.lastname: Wagner
authors.forename: Stefan
authors.initials: S
authors.lastname: Benz
authors.forename: Ottmar
authors.initials: O
authors.lastname: Möhler
authors.forename: Harald
authors.initials: H
authors.lastname: Saathoff
authors.forename: Martin
authors.initials: M
authors.lastname: Schnaiter
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schurath