Unique multispectral characteristics of ice clouds in the presence of large amounts of desert dust

In late winter and early spring in the northern hemisphere, baroclinic cyclones are responsible for entraining desert dust aerosols to high altitudes where they can influence ice particle properties. Two regions that regularly experience these entrainments are the Sahara Desert in North Africa and in the Taklamakan and Gobi Deserts in Northeast Asia.

This study combines satellite data and radiative transfer model simulations to explore several case studies in which dust may be influencing the microphysical properties of ice clouds. Under certain conditions, large amounts of dust can be ingested into the cloud tops where they produce unusual multispectral characteristics as compared with similar non-dust-entrained cyclones. Using the radiative transfer simulations as a basis for comparison, it is found that both passive and active satellite observations indicate an increase in the particle number concentrations and a reduction in the particle effective radius when large amounts of dust are observed. Observations of other interesting characteristics are also compared with "regular" cirrus clouds, such as longer cloud lifetimes (defined by parameters including brightness temperature) and well-defined cellular cloud top structures (normally associated with altocumulus).