Publication Date:
2019
Description:
Abstract
An ongoing challenge for cloud condensation nuclei (CCN) measurements is the inclusion of unactivated particles, which affects droplet activation parameterizations and aerosol indirect effects in models. For the first time, a reciprocal relationship between the critical diameter and critical supersaturation of activated droplets from the κ‐Köhler theory is derived to accurately count unactivated particles in CCN measurements. We conducted four‐day continuous observations to simultaneously measure the number concentration of CCN (NCCN) and aerosol. The results show that as supersaturation (SS) decreases from 0.186% at 25 °C, the proportion of the unactivated particles in the CCN measurements increases, reaching 88% at SS of 0.07%. Owing to the NCCN overestimation caused by NCCN‐SS parameterizations with uncorrected NCCN, there is significant overestimation of aerosol indirect effects, especially under low SS conditions. After removing unactivated particles, NCCN‐SS parameterizations are adjusted accordingly, which can improve simulations of aerosol‐cloud‐radiation interactions in models.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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