On the submicron aerosol distributions and CCN activity in and around the Korean Peninsula measured onboard the NASA DC-8 research aircraft during the KORUS-AQ field campaign

Aerosol and CCN number concentrations, and aerosol size distributions in and around the Korean Peninsula were measured onboard the NASA DC-8 research aircraft during the KORUS-AQ campaign in May and June of 2016. The average and standard deviation values of total aerosol number concentrations (diameter > 10 nm, N_CN10) in the boundary layer (below 1 km altitude) over Seoul, the Korean Peninsula, the Yellow Sea, the East Sea, and the South Sea were 12,318±7808, 10,721±8636, 7599±8583, 5759±6051, and 4186±4777 cm⁻³, respectively. Corresponding values for CCN number concentration at 0.6% supersaturation (N_CCN06) were 3358±1916, 3613±2242, 3422±1707, 2313±1039, and 1819±1328 cm⁻³, respectively. N_CN10 was highly variable according to region and period. In contrast, N_CCN06 was relatively invariant regardless of region and period. With the PMF analysis on the aircraft measured aerosol size distribution and N_CCN06 data, it was found that aerosol size distributions were composed of several distinct modes and they were different depending on regions. The aerosol hygroscopicity parameter κ was also estimated based on the PMF analysis results. The estimated κ values over Seoul, the Korean Peninsula, and the Yellow Sea were 0.11, 0.11, and 0.36, respectively. Lastly, the CCN closure experiments indicated that CCN concentration could be successfully estimated with the aerosol size distribution data and the estimated κ information from the aircraft measurements. Overall, it was demonstrated that PMF analysis technique could be applied to extract valuable information from limited aircraft measurement dataset.