Constraining cloud droplet number concentration in GCMs suppresses the aerosol indirect effect
Article first published online: 18 JUN 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 12, June 2009
How to Cite
2009), Constraining cloud droplet number concentration in GCMs suppresses the aerosol indirect effect, Geophys. Res. Lett., 36, L12807, doi:10.1029/2009GL038568., , , , , and (
- Issue published online: 18 JUN 2009
- Article first published online: 18 JUN 2009
- Manuscript Accepted: 20 MAY 2009
- Manuscript Revised: 15 MAY 2009
- Manuscript Received: 8 APR 2009
- aerosol indirect effects;
- global climate models
 Global aerosol-climate models with prognostic treatment of cloud droplet number concentration (CDNC) often prescribe lower bounds for CDNC or aerosol concentrations. Here we demonstrate that this possibly unphysical constraint reduces the simulated aerosol indirect effect by up to 80%, caused by extensively uniform CDNCs. In present-day conditions, the impact of the prescribed lower bound for CDNC is mainly visible over oceans, while with preindustrial emissions, large parts of both land and ocean areas are influenced. We furthermore show that imposing the same constraints on aerosol instead of on CDNC reduces the aerosol indirect effect to a lesser extent.