Ice nucleation properties of airborne and surface-collected desert dust

Y Boose, A Welti, J Atkinson, F Ramelli, A Danielczok, H Bingemer, M Plötze, B Sierau, Z A Kanji, U Lohmann

The ice nucleation behavior of transported airborne Saharan dust collected at four different locations and surface-collected dust from 9 different deserts worldwide has been investigated. We show that airborne dust tends to be less ice-active than surface-collected dust. The ice nucleation ability of desert dust at temperatures below 250 K correlates best with the weight fraction of quartz, while K-feldspar is the best predictor at 253 K. In only one case does organic or biological material seem to cause a high ice nucleation ability, which is lost after heating at 300°C. We suggest that ice nucleating particle parameterizations of airborne dust should include factors covering the feldspar and quartz fraction.

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