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A Bulk Parameterization of Giant CCN. Mechem, D. B., and Y. L. Kogan, 2008: J. Atmos. Sci , 65 , 2458–2466. Outline. Formulation of the GCCN parameterization Comparison to the bin microphysical approach Sensitivity to GCCN and ambient CCN concentrations Summary. - PowerPoint PPT Presentation
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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
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 **
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