Aerosol Effects on Cumulus Humilis

We present a unique set of airborne observations studying cloud condensation nuclei (CCN) in cumulus humilis during the Cumulus Humilis Aerosol Processing Study (CHAPS) campaign. We look into the connection between sized-resolved CCN composition and cloud properties using a new cloud representation scheme recently developed by Berg et al. in 2010. Findings of the CCN properties in cumulus humilis will be reported. One of our analyses links in situ measurements by the Aerodyne aerosol mass spectrometer (AMS), cloud aerosol and precipitation spectrometer (CAPS) probe, trace gases, and proton transfer mass spectrometer (PTRMS), which provide insights in atmospheric multiphase systems containing aerosols, droplets, and gases. For instance, by comparing the characteristic m/z obtained by AMS and carbon monoxide (CO) or isoprene, we can improve understanding in the role of primary and secondary organic aerosols in CCN and background aerosols. Another analysis will utilize the cumulus humilis binning representation scheme recently developed to study the correlation between CCN size-resolved composition and cloud properties and to understand the role of aerosol size and composition in clouds. Our study will provide an improved picture of CCN activation and aerosol effects on clouds in cumulus humilis.