GHG scenarios

[rnicholas@atmos_washington_edu]

The GHG concentration file provided with the current version of CAM (atm/cam/ggas/ghg_1870_2100_c040122.nc) contains a very brief note that suggests it's based on the IPCC B1 emissions scenario. Is there any documentation available for this file? I'm particularly interested in when, exactly, the real data ends and the projections for the B1 GHG concentrations begin.

On a related note, are similar input files available for other IPCC emission scenarios (A1F1, A1B, etc.)?

~Rob

 

[strandwg]

The GHG concentration file provided with the current version of CAM (atm/cam/ggas/ghg_1870_2100_c040122.nc) contains a very brief note that suggests it's based on the IPCC B1 emissions scenario. Is there any documentation available for this file?

The GHG concentrations for the CCSM3 IPCC B1 run are the same as those used for the PCM. They were derived from the IPCC TAR.

I'm particularly interested in when, exactly, the real data ends and the projections for the B1 GHG concentrations begin.

The GHG changes begin in 2000.

On a related note, are similar input files available for other IPCC emission scenarios (A1F1, A1B, etc.)?

Please see the following URL:

http://www.earthsystemgrid.org/brow.../ccsm/thredds/ccsm.3.0/ccsm.3.0.input.thredds

 

[rnicholas@atmos_washington_edu]

Great -- thanks for the info and the pointers to the SRES GHG files!

I'm wondering if you (or anyone else watching here) could also point me to the data sources from which these files were built and any scripts/code used to put the data into CAM-friendly format.

Thanks again...
Rob

 

[strandwg]

Great -- thanks for the info and the pointers to the SRES GHG files!

I'm wondering if you (or anyone else watching here) could also point me to the data sources from which these files were built and any scripts/code used to put the data into CAM-friendly format.

Actually, the GHG values were in a DATA statement in a piece of the PCM code. For CCSM, I merely pulled them out and manually inserted them into a template netCDF file. They're small files, so it's easier than writing some F90 code to do it.

 

[rnicholas@atmos_washington_edu]

I noticed that some of the SRES input files are at a different resolution than the resolution at which the model was run (e.g. the ozone file is at T42 while the IPCC runs were done at T85, as I understand it).

How smart is CAM about "scaling" the input files to the appropriate resolution? If, for example, I want do T42 runs using some of the SRES input files, can I get away with using the T85 SOx data that you pointed me to? Or do I need to regrid this data on my own before starting a T42 run? If CAM can do the scaling, does it work both ways (up and down)?

Thanks!

~Rob

 

[strandwg]

I noticed that some of the SRES input files are at a different resolution than the resolution at which the model was run (e.g. the ozone file is at T42 while the IPCC runs were done at T85, as I understand it).

The only input data that needs to be at the same resolution as CAM are the sulfate aerosols. The ozone data is appropriately interpolated to the CAM resolution.

How smart is CAM about "scaling" the input files to the appropriate resolution? If, for example, I want do T42 runs using some of the SRES input files, can I get away with using the T85 SOx data that you pointed me to? Or do I need to regrid this data on my own before starting a T42 run? If CAM can do the scaling, does it work both ways (up and down)?

As above, the sulfate aerosol needs to be T42 - the other input datasets are fine as they are. I can provide you with a T42 SOx dataset - which SRES runs are you planning to do?

 

[rnicholas@atmos_washington_edu]

As above, the sulfate aerosol needs to be T42 - the other input datasets are fine as they are. I can provide you with a T42 SOx dataset - which SRES runs are you planning to do?

I may try others in the future, but just the A2 scenario at this point.

 

[rnicholas@atmos_washington_edu]

Also, could you explain what the carbon scaling files are and how they're used?

 

[strandwg]

Also, could you explain what the carbon scaling files are and how they're used?

You'll need to check with the atmospheric model folks for those answers.

 

[rneale]

The scaling factors do what you would probably expect in that it scales the MMRs for the purpose of the radiation calculation (the default is 1.0).