Prescribed aerosol profile in CAM5

[chen63@illinois_edu]

Can we run prescribed aerosol profile in CAM5 now? i.e., setting the aerosol concentration in the atmosphere by some nc files and let the model read those files for aerosol information?

Thanks!

 

[hannay]

The MAM prescribed aerosol has been released yet. We expect this functionality will be available in the next release.
There is a option to run with BAM prescribed (-chem none) but this version of the model is not scientifically supported

As a reminder,
Modal Aerosol Modal (MAM) is the aerosol model in CAM5
Bulk Aerosol Model (BAM) is the aerosol model in CAM4

 

[piergiuseppe_fogli@cmcc_it]

I'm working with cesm1.1.1 fully coupled and I'm a bit confused about MAM/BAM options.The B1850 compset (cam4 physics) uses -chem none (BAM prescribed) while the B1850C5 compset (cam5) uses -chem trop_mam3 (MAM), right?What's the meaning of the -chem trop_bam option?What's the current state of the MAM prescribed aerosol that you mentioned?Thanks in advance.

 

[eaton]

The -chem trop_bam option is for a prognostic version of the bulk aerosols.cesm1_2_0 was released with the capability to run some simulations with prescribed MAM.  The currently available datasets provide both 1850 and present day climatologies.  There is not yet a dataset for a 20th century transient run.  It is also important to note that we expect cam5 simulations with prescribed MAM to be sensitive to the resolution of data.  The datasets available now are on the FV 1.9x2.5 deg grid.  We expect these datasets to closely reproduce the climate from using prognostic MAM at this resolution.  Using these datasets for runs at other resolutions will work because the datasets are interpolated to the model grid internally.  However, the results may not match those obtained using prognostic MAM very well.

 

[piergiuseppe_fogli@cmcc_it]

Thanks for your quick reply.How to activate prescribed MAM? -chem option, specific compset, namelist variable, ...?

 

[eaton]

Specifying '-chem none' to CAM's configure will by default set up prescribed bulk aerosols if the physics package is cam4, and will set up prescribed modal aerosols for cam5 physics.  Both these defaults may be overridden by user provided custom namelist settings.  It appears that there is a predefined compset, 1850_CAM5%PM, which is for cam5 w/ prescribed MAM using the 1850 climatology data.