Characteristics and impacts of the aerosol over Oklahoma determined from airborne measurements during the RACORO campaign

Aerosol and cloud droplet size distributions and CCN spectra were recorded from on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) research aircraft during the Routine Aerial Vehicles Program (AVP) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign. The RACORO project was a six-month field campaign designed to investigate the properties of thin clouds with low liquid water content, although a range of cloud types under various conditions were sampled. Over the six-month period, airborne data were collected during 59 flights having a total of about 260 flight hours. Here we will provide a summary of the collected aerosol data and of the link between cloud microphysics and the below cloud aerosol. The diverse cloud and aerosol properties encountered over the three seasons spanned during the campaign provides an excellent opportunity to assess variability in cloud response to changing aerosol loadings. The spatial coverage afforded by the airborne measurements has been coupled with details of the temporal variability of the aerosol observed at the Southern Great Plains (SGP) surface site that is within the domain of the research flights. We also report on the specific influence on aerosol and cloud droplet concentrations of smoke from fires that were especially numerous during the latter part of the campaign.