Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 10037-10050, 2017
https://doi.org/10.5194/acp-17-10037-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
28 Aug 2017
Sensitivities of Amazonian clouds to aerosols and updraft speed
Micael A. Cecchini1,4, Luiz A. T. Machado1, Meinrat O. Andreae2,12, Scot T. Martin3, Rachel I. Albrecht4, Paulo Artaxo5, Henrique M. J. Barbosa5, Stephan Borrmann2,6, Daniel Fütterer7, Tina Jurkat7, Christoph Mahnke2,6, Andreas Minikin8, Sergej Molleker6, Mira L. Pöhlker2, Ulrich Pöschl2, Daniel Rosenfeld9, Christiane Voigt6,7, Bernadett Weinzierl7,10, and Manfred Wendisch11 1Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, Brazil
2Biogeochemistry, Multiphase Chemistry, and Particle Chemistry Departments, Max Planck Institute for Chemistry, P.O. Box 3060, 55020, Mainz, Germany
3School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
4Departamento de Ciências Atmosféricas, Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG), Universidade de São Paulo (USP), Brazil
5Instituto de Física (IF), Universidade de São Paulo (USP), São Paulo, Brazil
6Institut für Physik der Atmosphäre (IPA), Johannes Gutenberg-Universität, Mainz, Germany
7Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, 82234 Wessling, Germany
8Flugexperimente, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
9Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
10Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
11Leipziger Institut für Meteorologie (LIM), Universität Leipzig, Stephanstr. 3, 04103 Leipzig, Germany
12Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
Abstract. The effects of aerosol particles and updraft speed on warm-phase cloud microphysical properties are studied in the Amazon region as part of the ACRIDICON-CHUVA experiment. Here we expand the sensitivity analysis usually found in the literature by concomitantly considering cloud evolution, putting the sensitivity quantifications into perspective in relation to in-cloud processing, and by considering the effects on droplet size distribution (DSD) shape. Our in situ aircraft measurements over the Amazon Basin cover a wide range of particle concentration and thermodynamic conditions, from the pristine regions over coastal and forested areas to the southern Amazon, which is highly polluted from biomass burning. The quantitative results show that particle concentration is the primary driver for the vertical profiles of effective diameter and droplet concentration in the warm phase of Amazonian convective clouds, while updraft speeds have a modulating role in the latter and in total condensed water. The cloud microphysical properties were found to be highly variable with altitude above cloud base, which we used as a proxy for cloud evolution since it is a measure of the time droplets that were subject to cloud processing. We show that DSD shape is crucial in understanding cloud sensitivities. The aerosol effect on DSD shape was found to vary with altitude, which can help models to better constrain the indirect aerosol effect on climate.

Citation: Cecchini, M. A., Machado, L. A. T., Andreae, M. O., Martin, S. T., Albrecht, R. I., Artaxo, P., Barbosa, H. M. J., Borrmann, S., Fütterer, D., Jurkat, T., Mahnke, C., Minikin, A., Molleker, S., Pöhlker, M. L., Pöschl, U., Rosenfeld, D., Voigt, C., Weinzierl, B., and Wendisch, M.: Sensitivities of Amazonian clouds to aerosols and updraft speed, Atmos. Chem. Phys., 17, 10037-10050, https://doi.org/10.5194/acp-17-10037-2017, 2017.
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Short summary
We study the effects of aerosol particles and updraft speed on the warm phase of Amazonian clouds. We expand the sensitivity analysis usually found in the literature by concomitantly considering cloud evolution and the effects on droplet size distribution (DSD) shape. The quantitative results show that particle concentration is the primary driver for the vertical profiles of effective diameter and droplet concentration in the warm phase of Amazonian convective clouds.
We study the effects of aerosol particles and updraft speed on the warm phase of Amazonian...
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