A Bulk Parameterization of Giant CCNMechem, D. B., and Y. L. Kogan, 2008: J. Atmos. Sci, 65, 24582466

OutlineFormulation of the GCCN parameterization

Comparison to the bin microphysical approach

Sensitivity to GCCN and ambient CCN concentrations

Summary

Giant CCN (GCCN; 1

LWC of deliquesced GCCN

a=5.8 , w=vertical velocity rd=GCCN dry radius

=3 or 4

A=3/4la3w0-0.36

Assuming r0=1rl=3 m =3

Comparison Three dimension : 40*40*51Horizontal grid:75m ; Vertical grid:25mDomain size : 3*3*1.25 kmSetCCN concentration : 628 cm-3k=0.49 ( )Ng=1360 L-1 ( )

SensitivityCCN : 628 (polluted case) cm-3 82 (clean case) cm-3

k=0.49 (for 0.2% supersaturation285 37 cm-3 )

GCCN :surface concentration 30,300,1360 L-1

Feingold et al.(1999)Clean

polluted

Follows Feingold et al.(1999)

A= albedo , =optical depth

susceptibility

SummaryMicrophysical 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 precipitationresults in only a modest change

Kogan 1991(P.3)

20~25 cloud rain water bulk *If w=0.5m/s GCCN=1~10 k=6.2~3.8 **