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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
16 Dec 2016
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Comparing calculated microphysical properties of tropical convective clouds at cloud base with measurements during the ACRIDICON-CHUVA campaign
Ramon Campos Braga1, Daniel Rosenfeld2, Ralf Weigel3, Tina Jurkat4, Meinrat O. Andreae5,9, Manfred Wendisch6, Mira L. Pöhlker5, Thomas Klimach5, Ulrich Pöschl5, Christopher Pöhlker5, Christiane Voigt3,4, Christoph Mahnke3, Stephan Borrmann3, Rachel I. Albrecht7, Sergej Molleker8, Daniel A. Vila1, Luiz A. T. Machado1, and Paulo Artaxo10 1Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, Brasil
2Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel
3Institut für Physik der Atmosphäre, Johannes Gutenberg-Universität, Mainz, Germany
4Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
5Multiphase Chemistry and Biogeochemistry Departments, Max Planck Institute for Chemistry, 55020 Mainz, Germany
6Leipziger Institut für Meteorologie (LIM), Universität Leipzig, Stephanstr. 3, 04103 Leipzig, Germany
7Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, Brazil
8Max Planck Institute for Chemistry (MPI), Particle Chemistry Department, Mainz, Germany
9Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, USA
10Instituto de Física (IF), Universidade de São Paulo (USP), São Paulo, Brazil
Abstract. Reliable aircraft measurements of cloud microphysical properties are essential for understanding liquid convective cloud formation. In September 2014, the properties of convective clouds were measured with a Cloud Combination Probe (CCP), a Cloud and Aerosol Spectrometer (CAS-DPOL), and a cloud condensation nuclei (CCN) counter on board the HALO (High Altitude and Long Range Research Aircraft) aircraft during the ACRIDICON-CHUVA campaign over the Amazon region. An intercomparison of the cloud drop size distributions (DSDs) and the cloud water content derived from the different instruments generally shows good agreement within the instrumental uncertainties. The objective of this study is to validate several parameterizations for liquid cloud formation in tropical convection. To this end the directly measured cloud drop concentrations (Nd) near cloud base were compared with inferred values based on the measured cloud base updraft velocity (Wb) and cloud condensation nuclei (CCN) vs. supersaturation (S) spectra. The measurements of Nd at cloud base were also compared with drop concentrations (Na) derived on the basis of an adiabatic assumption and obtained from the vertical evolution of cloud drop effective radius (re) above cloud base. The results demonstrate agreement of the measured and theoretically expected values of Nd based on CCN, S, Wb at cloud base, and the height profile of re. The measurements of NCCN(S) and Wb did reproduce the observed Nd. Furthermore, the vertical evolution of re with height reproduced the observation-based nearly adiabatic cloud base drop concentrations, Na. Achieving such good agreement is possible only with accurate measurements of DSDs. This agreement supports the validity of the applied parameterizations for continental convective cloud evolution, which now can be used more confidently in simulations and satellite retrievals.

Citation: Braga, R. C., Rosenfeld, D., Weigel, R., Jurkat, T., Andreae, M. O., Wendisch, M., Pöhlker, M. L., Klimach, T., Pöschl, U., Pöhlker, C., Voigt, C., Mahnke, C., Borrmann, S., Albrecht, R. I., Molleker, S., Vila, D. A., Machado, L. A. T., and Artaxo, P.: Comparing calculated microphysical properties of tropical convective clouds at cloud base with measurements during the ACRIDICON-CHUVA campaign, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-872, in review, 2016.
Ramon Campos Braga et al.
Ramon Campos Braga et al.


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