A comparison between predicted and measured concentrations of desert dust-related ice-nucleating particles in the troposphere

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Wednesday, 7 January 2015
Ottmar Möhler, Karlsruhe Institute of Technology, Karlsruhe, Germany; and P. J. DeMott, L. B. Hande, C. Hoose, M. Niemand, and R. Ullrich

In tropospheric clouds which exist at temperatures between 0°C and about -35°C, the ice-phase can only be initiated by heterogeneous ice nucleation processes which are induced by a variety of different aerosol particles, so-called ice-nucleating particles (INPs). In such clouds, primary ice formation followed by a series of secondary processes often also initiates precipitation, which underlines the need for measurements or quantitative predictions of the INP abundance throughout the troposphere and for related formulations of primary ice formation rates in cloud, weather and climate models.

In the previous years, several approaches or parameterisations have been developed for models in order to predict the INP abundance as function of mainly temperature and aerosol properties. Here we focus on desert dust as major source of atmospheric INP and have a closer look at two of these approaches, one relying on the number concentration of particles larger than 0.5 µm, the other on the total surface area. We will show and discuss several case studies in the laboratory and the field were these approaches have been compared to each other and to direct measurements of INP concentrations.