Light scattering by quasi-spherical ice crystals in tropical cirrus
T. Nousiainen*,1, H. Lindqvist1 and G. M. McFarquhar2
- 1 Department of Physics, P.O. box 48, FI-00014 University of Helsinki, Finland.
- 2 University of Illinois, Department of Atmospheric Sciences, 105 S. Gregory Street, Urbana, IL 61801-3070, USA.
Shape statistics of small, quasi-spherical ice crystals are compiled through analysis of images collected by the Cloud Particle Imager (CPI) in tropical cirrus. Ray-optics simulations are conducted to obtain their single-scattering properties at 550 nm wavelength. Small tropical ice crystals are found to be more spherical than those in midlatitude cirrus and, correspondingly, their asymmetry parameters are higher. The difference is, however, not significantly larger than the variability within tropical cirrus. Sensitivity studies conducted imply that the asymmetry parameter is very sensitive to internal inhomogeneity about which no data currently exist.
- * Corresponding author