GEOPAC - A geographical perspective on aerosol-cloud interactions
Final Report Abstract
Within GEOPAC, we studied system-scale relationships between aerosol and cloud properties as well as regional patterns therein, based on the analysis of passive-sensor and active-sensor satellite products. Most importantly, we were able to: ● Successfully link cloud properties to aerosol and environmental conditions in a multivariate statistical approach. In a way not possible before with observation data alone, we were able to show that aerosol distinctly contributes to the development of cloud properties, but its effect is smaller than that of other environmental factors. ● Show that there are distinct ‘regimes’, differentiated by the aerosol loading at which cloud properties are most sensible to small changes in aerosol. The presence of dust aerosol and the prevalent humidity conditions were shown to be crucial. ● Quantify and regionally differentiate regions in between ‘pure’ cloud and ‘pure’ aerosol, using passive-sensor and active-sensor satellite data. These regions, comprising up to 25% of the Earth’s area, have been largely ignored in observationbased studies of aerosol-cloud interactions, but will need to play a more prominent role in future model evaluation. ● In an evaluation of geostationary satellite data, show the important role of air mass transport in determining the properties of a stratocumulus cloud field. An area in the South-East Atlantic, often studied for its quasi-constant cloud conditions was shown to be less constant than assumed. With this project we were able to extract new global and regional information on the aerosolcloud system. A lot has been learned, but at the same time, new research questions appeared. Future research, using models and new satellite systems, will be able to build on the findings of GEOPAC.
Publications
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(2015). How thermodynamic environments control stratocumulus microphysics and interactions with aerosols. Environmental Research Letters, 10(2), 24004
Andersen, H., & Cermak, J.
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(2015). Where Aerosols Become Clouds—Potential for Global Analysis Based on CALIPSO Data. Remote Sensing, 7(4), 4178–4190
Fuchs, J., & Cermak, J.
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(2016). Global observations of cloudsensitive aerosol loadings in low-level marine clouds. Journal of Geophysical Research: Atmospheres, 121(21), 12936--12946
Andersen, H., Cermak, J., Fuchs, J., & Schwarz, K.
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(2017). Understanding the drivers of marine liquid-water cloud occurrence and properties with global observations using neural networks. Atmospheric Chemistry and Physics Discussions, 1–16
Andersen, H., Cermak, J., Fuchs, J., Knutti, R., & Lohmann, U.
