Test the impacts of changes in cloud fraction on photolysis reactions

[lshen2009]

Your name

Lu Shen

Your affiliation

Peking University

Please provide a clear and concise description of your question or discussion topic.

I am interested in testing the impacts of changes in cloud fraction on tropospheric photolysis reactions. Could you provide guidance on how to approach this analysis effectively? Thank you.

[yantosca]

Thanks @lshen2009. I think this would be a good use case for the new KPP-Standalone box model, which is now available in GEOS-Chem 14.5.1. Please see our new documentation:

• Use the KPP-Standalone box model to test chemical mechanisms

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[lizziel]

Hi @lshen2009, in case it is helpful, there is a feature in the Cloud-J interface file that allows you to turn off the contributions of various sources of optical depth used in photolysis. For example, you could retrieve J-values for contribution from cloud only. See

geos-chem/GeosCore/cldj_interface_mod.F90

Lines 347 to 359 in 483ceec

	! Set debugging logicals to turn optical depth sources on/off. If using,
	! uncomment where they are appear later in this file. They are commented out by
	! default to avoid unnecessary slow-down.
	use_liqcld = .true.
	use_icecld = .true.
	use_dust = .true.
	use_so4 = .true.
	use_bc = .true.
	use_oc = .true.
	use_sala = .true.
	use_salc = .true.
	use_stratso4 = .true.
	use_psc = .true.

and

geos-chem/GeosCore/cldj_interface_mod.F90

Lines 879 to 890 in 483ceec

	! Debugging option to set contributions from different sources to zero.
	! Uncomment if using.
	!IF ( .NOT. use_liqcld ) LWP(:) = 0.d0
	!IF ( .NOT. use_icecld ) IWP(:) = 0.d0
	!IF ( .NOT. use_dust ) AERSP(:,4:10) = 0.d0
	!IF ( .NOT. use_so4 ) AERSP(:,11:15) = 0.d0
	!IF ( .NOT. use_bc ) AERSP(:,16:20) = 0.d0
	!IF ( .NOT. use_oc ) AERSP(:,21:25) = 0.d0
	!IF ( .NOT. use_sala ) AERSP(:,26:30) = 0.d0
	!IF ( .NOT. use_salc ) AERSP(:,31:35) = 0.d0
	!IF ( .NOT. use_stratso4 ) AERSP(:,36) = 0.d0
	!IF ( .NOT. use_psc ) AERSP(:,37) = 0.d0

.