CCN Closure Analysis for the ACTIVATE Campaign
Cassidy Soloff1, Ewan Crosbie2,3, Simon Kirschler4,5, Richard Moore2, Michael Shook2, Shuaiqi Tang6,7, Kenneth L. Thornhill2, Christiane Voigt4,5, Hailong Wang6, Edward Winstead2, Luke D. Ziemba2, Armin Sorooshian1
1Univerisity of Arizona,
2NASA Langley Research Center,
3Analytical Mechanics Associates,
4Institute of Atmospheric Physics, German Aerospace Center,
5Institute of Atmospheric Physics, University Mainz, Germany,
6 Pacific Northwest National Laboratory,
7Nanjing University
The northwest Atlantic Ocean is an ideal location for studying aerosol-cloud interactions at the interface of the anthropogenic/continental and marine environments because of the diverse set of meteorological conditions and emission sources. Conducting cloud condensation nuclei (CCN) closure analysis in this complex region across winter and summer seasons allows us to examine the performance of airborne instrumentation and model representations of the aerosol-CCN link. Using data from 179 research flights across all three years of NASA’s Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE, 2020-2022), we predict CCN concentrations using particle size spectra and bulk chemical composition. We compare these predictions with in situ measurements of CCN. Predictions were made using Köhler theory with assumed hygroscopicity parameters (κ) from previous work. κ calculated from particle chemistry was compared with the retrieved κ based on CCN and total particle observations. Closure was achieved for most of the measurements in the campaign, but Köhler theory failed to predict CCN accurately at CCN concentrations below ~50 cm-3 and for the winter and marine measurements at low organic mass fractions. Results from this analysis are compared with other regions.