Atmos. Chem. Phys. Discuss., 12, 28609-28660, 2012
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The fine-scale structure of the trade wind cumuli over Barbados – an introduction to the CARRIBA project
H. Siebert1,2, J. Bethke1, E. Bierwirth3, T. Conrath1, K. Dieckmann1, F. Ditas1, A. Ehrlich3, D. Farrell4, S. Hartmann1, M. A. Izaguirre5, J. Katzwinkel1, L. Nuijens2, G. Roberts6,7, M. Schäfer3, R. A. Shaw8, T. Schmeissner1, I. Serikov2, B. Stevens2, F. Stratmann1, B. Wehner1, M. Wendisch3, F. Werner3, and H. Wex1
1Leibniz Institute for Tropospheric Research, Leipzig, Germany
2Max-Planck-Institute for Meteorology, Hamburg, Germany
3Leipzig Institute for Meteorology, University of Leipzig, Leipzig, Germany
4Caribbean Institute for Meteorology and Hydrology, Barbados, West Indies
5University of Miami, Miami, FL, USA
6Météo-France, Toulouse, France
7Scripps Institution of Oceanography, Center for Atmospheric Sciences, La Jolla, USA
8Michigan Technological University, Michigan, USA

Abstract. The CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over BArbados) project with focus on trade wind cumuli over Barbados is introduced. The project is based on two one-month field campaigns in November 2010 (climatic wet season) and April 2011 (climatic dry season). Observations are based on helicopter-borne and ground-based measurements in a square of 100 km2 off the coast of Barbados. CARRIBA is accompanied by long-term observations at the Barbados Cloud Observatory located at the East coast of Barbados since early in 2010 and which provides longer-term context for the CARRIBA measurements. Deployed instrumentation and sampling strategy are presented together with a classification of the meteorological conditions. The two campaigns were influenced by different air masses advected from the Caribbean area, the Atlantic Ocean, as well as the African continent which led to distinct aerosol conditions. Therefore, pristine conditions with low aerosol particle number concentrations of ~100 cm3 were alternating with periods influenced by Saharan dust or aerosol from biomass burning resulting in comparable high number concentrations ~500 cm3. The later was originating from both, the Caribbean area and Africa. The shallow cumulus clouds responded to the different aerosol conditions with a wide range of mean droplet sizes and number concentrations. Effective radii in the range of 7 to 18 μm have been observed. Finally, the four leading topics of CARRIBA – Clouds, Aerosol, Radiation and tuRbulence – are motivated and illustrated by selected findings and measurement examples.

Citation: Siebert, H., Bethke, J., Bierwirth, E., Conrath, T., Dieckmann, K., Ditas, F., Ehrlich, A., Farrell, D., Hartmann, S., Izaguirre, M. A., Katzwinkel, J., Nuijens, L., Roberts, G., Schäfer, M., Shaw, R. A., Schmeissner, T., Serikov, I., Stevens, B., Stratmann, F., Wehner, B., Wendisch, M., Werner, F., and Wex, H.: The fine-scale structure of the trade wind cumuli over Barbados – an introduction to the CARRIBA project, Atmos. Chem. Phys. Discuss., 12, 28609-28660, doi:10.5194/acpd-12-28609-2012, 2012.
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