A Bulk Parameterization of Giant CCN

1. A Bulk Parameterization of Giant CCN Mechem, D. B., and Y. L. Kogan, 2008: J. Atmos. Sci, 65, 2458–2466

2. Outline Formulation of the GCCN parameterization Comparison to the bin microphysical approach Sensitivity to GCCN and ambient CCN concentrations Summary

3. Giant CCN (GCCN; 1<r<10 μm) 3.5 μm NaCl deliquesces to a 20.2 μm nucleus

4. LWC of deliquesced GCCN a=5.8 , w=vertical velocity rd=GCCN dry radius

5. α=3 or 4

6. A=3/4πρla3w0-0.36

7. Assuming r0=1、rl=3 μm ，α=3

8. Comparison Three dimension : 40*40*51 Horizontal grid:75m ; Vertical grid:25m Domain size : 3*3*1.25 km Set CCN concentration : 628 cm-3 k=0.49 ( ) Ng=1360 L-1 ( )

10. Sensitivity CCN : 628 (polluted case) cm-3 82 (clean case) cm-3 k=0.49 (for 0.2% supersaturation，285、 37cm-3 ) GCCN :surface concentration 30,300,1360 L-1

11. Clean polluted Feingold et al.(1999)

12. Follows Feingold et al.(1999) A= albedo , τ=optical depth  susceptibility

14. Summary Microphysical and cloud radiative properties exhibit the greatest sensitivity to the addition of GCCN for a large background aerosol Concentration. The addition of GCCN to a clean background environment with preexisting active precipitation results in only a modest change

16. Kogan 1991(P.3)