Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-419
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
14 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Understanding aerosol–cloud interactions through modelling the development of orographic cumulus congestus during IPHEx
Yajuan Duan1, Markus D. Petters2, and Ana P. Barros1 1Department of Civil and Environmental Engineering, Duke University, Durham, NC, USA
2Department of Marine Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA
Abstract. A new cloud parcel model (CPM) including activation, condensation, collision-coalescence, and lateral entrainment processes is presented here to investigate aerosol-cloud interactions (ACI) in cumulus development prior to rainfall onset. The CPM was applied with surface aerosol measurements to predict the vertical structure of cloud development at early stages, and the model results were compared with airborne observations of cloud microphysics and thermodynamic conditions collected during the Integrated Precipitation and Hydrology Experiment (IPHEx) in the inner region of the Southern Appalachian Mountains (SAM). Sensitivity analysis was conducted to examine the model response to variations in key ACI physical parameters. The condensation coefficient ac plays a governing role in determining the cloud droplet number concentration (CDNC), liquid water content (LWC), and droplet size distribution. Lower values of ac lead to higher cloud droplet number concentrations, broader droplet spectra, and higher maximum supersaturation near cloud base. The simulated vertical structure of CDNC exhibits strong nonlinear sensitivity to entrainment strength and condensation efficiency illustrative of competitive interference between turbulent dispersion and activation processes. Further, simulated CDNC exhibits high sensitivity to variations in initial aerosol concentration at cloud base, but weak sensitivity to aerosol hygroscopicity. These findings provide new insights into determinant factors of convective cloud formation leading to mid-day warm season rainfall in complex terrain.
Citation: Duan, Y., Petters, M. D., and Barros, A. P.: Understanding aerosol–cloud interactions through modelling the development of orographic cumulus congestus during IPHEx, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-419, in review, 2018.
Yajuan Duan et al.
Yajuan Duan et al.
Yajuan Duan et al.

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Short summary
To investigate aerosol–cloud interactions in cumulus development, a new cloud parcel model is developed to predict the vertical structure of cloud formation at early stages and evaluated against airborne observations during the Integrated Precipitation and Hydrology Experiment over the Southern Appalachian Mountains. These findings provide new insights into determinant factors of convective cloud formation leading to mid-day warm season rainfall in complex terrain.
To investigate aerosol–cloud interactions in cumulus development, a new cloud parcel model is...
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