Frequency Dependent Complex Refractive Indices of Supercooled Liquid Water and Ice Determined from Aerosol Extinction Spectra

Complex refractive indices of supercooled liquid water at 240, 253, 263, and 273 K, and ice at 200, 210, and
235 K in the mid infrared from 460 to 4000 cm-1 are reported. The results were obtained from the extinction
spectra of small (micron-size) aerosol particles, recorded using the cryogenic flow tube technique. An improved
iterative procedure for retrieving complex refractive indices from extinction measurements is described. The
refractive indices of ice determined in the present study are in good agreement with data reported earlier. The
temperature region and range of states covered in the present work are relevant to the study of upper tropospheric
and stratospheric aerosols and clouds.