标题：Supersaturations, microphysics and nitric acid partitioning in a cold cirrus cloud observed
during CR-AVE 2006: an observation–modelling intercomparison study
摘要：Supersaturations, microphysics and nitric acid partitioning in a very cold subvisible
tropical cirrus cloud observed on 2 February 2006, during the field campaign CR-AVE, are
studied by comparing a simulated set of possible cloud development scenarios with the in
situ observations. The scenario that best matches the observations is a cirrus
cloud forming by heterogeneous freezing of a small number of ice nuclei with
subsequent unimpeded mass accommodation of water on ice. Variation of the freezing
process, the accommodation coefficient or the amount of available water leads to
simulated clouds that differ microphysically from the observed cloud in important
respects. In particular, the simulations suggest that heterogeneous ice nucleation or
another freezing mechanism producing only a low number of ice crystals could be an
important process for cold cirrus cloud formation, possibly explaining the frequent
observations of high supersaturations inside the cirrus cloud in this temperature regime.
