OVERVIEW OF THE CUMULUS HUMILIS AEROSOL PROCESSING STUDY

摘要

During the summer of 2007, CHAPS investigated changes in the chemical and optical properties of aerosols due to their interaction with shallow cumuli. Aerosols influence climate directly by scattering and absorbing radiation and indirectly through their influence on cloud microphysical and dynamical properties. The Intergovernmental Panel on Climate Change (IPCC) concluded that the global radiative forcing due to aerosols is large and in general cools the planet (Forster et al. 2007). But the uncertainties in these estimates are also large due to our poor understanding of many of the important processes related to aerosols and clouds. To address this uncertainty, Ghan and Schwartz (2007) proposed an integrated strategy for addressing issues relatedto aerosols and aerosol processes. Using this conceptual framework, the Cumulus Humilis Aerosol Processing Study (CHAPS) is a stage 1 activity, that is, a detailed process study. The specific focus of CHAPS was to provide concurrent observations of the chemical composition of the activated [particles that are currently serving as cloud condensation nuclei (CCN)] and nonactivated aerosols, the scattering and extinction profiles, and detailed aerosol and droplet size spectra in the vicinity of Oklahoma City, Oklahoma, during June 2007.