CCN predictions : Is theory sufficient for assessments of the 3 indirect effect ?

7 [1] This study quantitatively assesses the sensitivity of 8 cloud droplet number (CDNC) to errors in cloud 9 condensation nuclei (CCN) predictions that arise from 10 application of Köhler theory. The CDNC uncertainty is 11 assessed by forcing a droplet activation parameterization 12 with a comprehensive dataset of CCN activity and aerosol 13 size and chemical composition obtained during the ICARTT 14 field campaign in August 2004. Our analysis suggests that, 15 for a diverse range of updraft velocity, droplet growth 16 kinetics and airmass origin, the error in predicted CDNC 17 is (at most) half of the CCN prediction error. This means 18 that the typical 20–50% error in ambient CCN closure 19 studies would result in a 10–25% error in CDNC. For the 20 first time, a quantitative link between aerosol and CDNC 21 prediction errors is available, and can be the basis of a robust 22 uncertainty analysis of the first aerosol indirect effect. 23 Citation: Sotiropoulou, R.-E. P., J. Medina, and A. Nenes 24 (2006), CCN predictions: Is theory sufficient for assessments of 25 the indirect effect?, Geophys. Res. Lett., 33, LXXXXX, 26 doi:10.1029/2005GL025148.