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Radiaitve properties and hyrgroscopic growth of sulphate aerosols

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Radiaitve properties and hyrgroscopic growth of sulphate aerosols

Dear Forum Members,

I am using CESM 1.0.4 and CAM4 to study the effects of sulfate aerosols (both background and volcanic size) by prescribing them in stratosphere. 

1) Could somebody provide a reference on how longwave and shortwave properties of sulfate aerosols are parametrised in the model when using CAM4?

2) Also any reference on how hygroscopic effects are calculated in the model for sulphate aerosols? 

I have seen the corresponding section in the technical document (NCAR/TN-485+STR) but if anybody can provide more details (a journal paper corresponding to the calculations) it would be of great help for me.

3) By tweaking relative humidity values in stratosphere in models/atm/cam/src/physics/cam/aer_rad_props.F90 program, I could see that hygrscopic growth is affecting background aerosols but is absent in case of volcanic size aerosols. Could somebody please confirm this?

Thank you in advance,



CAM4 is generally run with interactive bulk aerosols in the troposphere, and prescribed volcanic aerosols in the stratosphere. There are no background stratospheric aerosols included in CAM4. However, the tropospheric aerosols include sulfates. You can find a list of the optical properties for each radiatively active gas and aerosol type in your CaseDocs/atm_in namelist, i.e.:

 rad_climate= 'P_Q:H2O', 'D_O2:O2', 'D_CO2:CO2', 'D_ozone:O3', 'D_N2O:N2O', 'D_CH4:CH4', 'D_CFC11:CFC11',

  'D_CFC12:CFC12', 'D_sulf:/fis/cgd/cseg/csm/inputdata/atm/cam/physprops/',












D_sulf: points to the tropospheric sulfate aerosol optical properties

D_VOLC_MMR: points to the prescribed stratospheric volcanic aerosol optical properties


Mike Mills
WACCM Liaison
Atmospheric Chemistry Division
NCAR Foothills Lab
Boulder, Colorado USA


Thank you very much for the details Mills.

In the two nc files '' and '', variable opticsmethod shows that one is 'hygro' and the other is 'nonhygro' type.

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