Determination of vertical profiles of aerosol size spectra from aircraft radiative flux measurements: 2. The effect of particle nonsphericity

The effect of particle nonsphericity upon the retrieval of panicle size distributions, computed from aircraft radiative flux measurements, has been examined for the data of September 4, 1974. The particle inversion procedure is identical to that described by Kondratyev et al. (1981), involving quadramodal particle size spectra. Nonspherical particle attenuation coefficients and phase functions were calculated according to the semi-empirical approach developed by Pollack and Cuzzi. It was found that variations of the phase function by nonspherical panicles affected the retrieval of particle size spectra to a far greater degree than did variations of panicle scattering efficiency. Nonspherical panicles generally have smaller values of asymmetry factor than do their spherical counterparts. The inferred size spectra of nonspherical panicles show decreased values both of large and small panicle number densities along with a broadening of the large particle mode to include particles of larger sizes.