Stratocumulus (Sc) clouds in the marine boundary layer (MBL) are a cornerstone of the Southeast Pacific (SEP) climate system and important modulators of the Earth's radiation budget. Sc clouds exhibit a wide range of properties and morphologies and contribute considerably to the overall mesoscale variability of the region. However, the mechanisms that control the mesoscale variability of MBL clouds, influence their microphysical and macrophysical properties as well as the interactions between aerosols and clouds are poorly understood, not very well quantified and may even be misrepresented in current large-scale and mesoscale models.
This project will focus upon the numerical simulation of marine boundary layer clouds in the SEP region. The major goals are (a) to better understand the microphysical and dynamical mechanisms that lead to the observed mesoscale variability of microphysical and macrophysical Sc cloud properties; (b) to investigate the role of aerosols and aerosol-cloud interactions for the formation, mesoscale organization and maintenance of pockets of open cells (POCs); and (c) to improve the representation of microphysical and macrophysical properties of MBL clouds as well as aerosols in a regional model. For the evaluation of the model simulations and the comparison with observations we will use a combination of extensive multi-platform measurements from the VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) Regional Experiment (REx) and satellite observations.
The simulations with the regional model will permit mesoscale variability that typically is crucial for organized mesoscale convection, but also allow the context of a real world scenario. Thus, the regional model simulations will bridge the gap induced by the scale disparity between large eddy simulations and simulations with global circulation models.
Intellectual merit: The expected improvement in understanding of the microphysical and dynamical processes leading to the observed mesoscale variability of marine boundary layer clouds in the Southeast Pacific region. This knowledge will be of great value for improving microphysical parameterizations of aerosol-cloud interactions with the vision to better represent mesoscale cloud variability of marine Sc clouds in regional and global models, which will then help to narrow down uncertainties of aerosol indirect effects and cloud feedbacks in the global climate system.
Broader impacts: Newly acquired data sets will be made available at the NCAR EOL database and shared with the broader VOCALS community. Research results will be disseminated through presentations at national and international workshops and conferences. The project will also promote graduate education and training. Collaborating with other scientists, the research activity will help to improve regional models and participation via model intercomparison.
