On the Dependence of Cirrus Parametrizations on the Cloud Origin

Abstract

Parametrizations of Arctic cirrus particle size distributions are presented depending on the cloud origin, either in situ or liquid. The data set used originate from balloon-borne measurements above Kiruna during winter. The observed particle size distributions are represented by gamma functions. The gamma coefficients exhibit large differences with regard to cloud origin. The functions for Arctic cirrus confirm established parametrizations for continental cirrus sorted by two particle size modes but differ from others depending only on temperature. We suppose that the agreement between the parametrizations of the geographically different cirrus is because in situ and liquid origin cirrus also distinguish by particle size modes. Since cloud sorting by their origin is based on physical processes which are independent of geographical region, we further hypothesize that these cloud-type-based parametrizations might be generally valid for use in global models and satellite retrievals, given the distribution of the cloud types is known.