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  Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON-CHUVA campaign

Braga, R. C., Rosenfeld, D., Weigel, R., Jurkat, T., Andreae, M. O., Wendisch, M., et al. (2017). Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON-CHUVA campaign. Atmospheric Chemistry and Physics, 17(12), 7365-7386. doi:10.5194/acp-17-7365-2017.

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Braga, Ramon Campos1, Author
Rosenfeld, Daniel1, Author
Weigel, Ralf1, Author
Jurkat, Tina1, Author
Andreae, M. O.2, Author              
Wendisch, Manfred1, Author
Pöhlker, M. L.3, Author              
Klimach, T.4, Author              
Pöschl, U.3, Author              
Pöhlker, C.3, Author              
Voigt, Christiane1, Author
Mahnke, Christoph1, Author
Borrmann, S.4, Author              
Albrecht, Rachel I.1, Author
Molleker, S.4, Author              
Vila, Daniel A.1, Author
Machado, Luiz A. T.1, Author
Artaxo, Paulo1, Author
Affiliations:
1external, ou_persistent22              
2Biogeochemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826286              
3Multiphase Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826290              
4Particle Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826291              

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 Abstract: The objective of this study is to validate parameterizations that were recently developed for satellite retrievals of cloud condensation nuclei supersaturation spectra, NCCN(S), at cloud base alongside more traditional parameterizations connecting NCCN(S) with cloud base updrafts and drop concentrations. This was based on the HALO aircraft measurements during the ACRIDICON–CHUVA campaign over the Amazon region, which took place 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 CCN counter onboard the HALO aircraft. An intercomparison of the cloud drop size distributions (DSDs) and the cloud water content (CWC) derived from the different instruments generally shows good agreement within the instrumental uncertainties. 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 NCCN(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 measurements of NCCN(S) and Wb reproduced the observed Nd within the measurements uncertainties when the old (1959) Twomey's parameterization was used. The agreement between the measured and calculated Nd was only within a factor of 2 with attempts to use cloud base S, as obtained from the measured Wb, Nd, and NCCN(S). This underscores the yet unresolved challenge of aircraft measurements of S in clouds. Importantly, the vertical evolution of re with height reproduced the observation-based nearly adiabatic cloud base drop concentrations, Na. The combination of these results provides aircraft observational support for the various components of the satellite-retrieved methodology that was recently developed to retrieve NCCN(S) under the base of convective clouds. This parameterization can now be applied with the proper qualifications to cloud simulations and satellite retrievals.

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Language(s): eng - English
 Dates: 2017
 Publication Status: Published in print
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 Rev. Type: -
 Identifiers: ISI: 000403917900004
DOI: 10.5194/acp-17-7365-2017
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Title: Atmospheric Chemistry and Physics
Source Genre: Journal
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Publ. Info: Katlenburg-Lindau, Germany : European Geosciences Union
Pages: - Volume / Issue: 17 (12) Sequence Number: - Start / End Page: 7365 - 7386 Identifier: ISSN: 1680-7316
CoNE: https://pure.mpg.de/cone/journals/resource/111030403014016