Aerosol indirect effects questions

1. Aerosol indirect effects questions • How is the CCN spectrum related to dry aerosol number size distribution (NSD)? • How well can CCN be predicted from dry NSD? • How correlated is AOT and the CCN spectrum? • Can CCN values be correlated with CN? • How important is aerosol NSD >1 µm (GCCN)? • How can aerosol parameters be evaluated?

2. Aerosol NSD and CCN Spectrum Source: Ackerman et al., 2008

3. Aerosol NSD and CCN at 0.2% Source: Van Reken et al., 2003

4. Aerosol NSD and CCN at 0.85% Source: Van Reken et al., 2003

5. AOT at 500 nm and CCN at 0.4% SS Source: Andreae et al., 2009

6. CN and CCN at 0.4% SS Source: Andreae et al., 2009

7. GCCN and Drizzle Formation Source: Feingold et al., 1999

8. GCCN and Drizzle Formation Source: Feingold et al., 1999

9. Possible two-pronged approach? • Simple initial estimate • estimate limited CCN spectrum based on AOT or extinction at a single wavelength • estimate of CN based on CCN • More challenging retrieval • calculate ambient aerosol size distribution parameters in two modes using data at added λ • seek better techniques to extend to smaller sizes

10. How can parameters be evaluated? • Using LES of broken low marine clouds with diagnostic aerosol treatment • ∆CRFTOA = f(∆NACCN, ∆NGCCN, ∆r, ∆σ, ∆RH, ∆AOT, ∆hygroscopicity//) • Using LES with prognostic aerosol treatment • ∆CRFTOA = f(∆NACCN) • how to handle ∆CRFTOA = f(∆NGCCN)? • Using literature estimates • ∆CRFTOA = f(∆NIN, ∆AAOT, ∆nonsphericity)