How to set constant nitrogen deposition in coupled simulations

[Yuexuanzi Wang]

Hello,
I want to hold the nitrogen deposition constant in a coupled simulations (CAM6.0 & CLM5.0) in CESM2.1.3.
In CLM5.0 User's Guide, I find a discription: "In coupled simulations, N depositions fluxes are passed to the land model at the frequency of the time step (every half hour) through the coupler".
I wonder if this means the variables in lnd_in:

&ndepdyn_nml​

model_year_align_ndep = 2015​

ndep_taxmode = 'cycle'​

ndep_varlist = 'NDEP_month'​

ndepmapalgo = 'bilinear'​

stream_fldfilename_ndep = '/CESM/inputdata/lnd/clm2/ndepdata/fndep_clm_f09_g17.CMIP6-SSP1-2.6-WACCM_1849-2101_monthly_c191007.nc'​

stream_year_first_ndep = 2015​

stream_year_last_ndep = 2101​

aren't work in the coupled simulation?
So how can I set constant nitrogen deposition in coupled simulations?
Any help with this would be appreciated. Thanks a lot.

 

[oleson]

It's my understanding that unless you are running CAM with full chemistry, CLM will still use the nitrogen deposition stream you noted.

 

[Yuexuanzi Wang]

It's my understanding that unless you are running CAM with full chemistry, CLM will still use the nitrogen deposition stream you noted.

Thanks for your reply. So if I use the CAM-Chem coupled with CLM-BGC, then the nitrogen deposition stream above will be not used? At that time, the nitrogen deposition will be sent from CAM-Chem to CLM-BGC?

 

[oleson]

I believe that is true.

 

[Yuexuanzi Wang]

I believe that is true.

So can I have a way to use the nitrogen deposition stream when I couple the CAM-Chem with CLM-BGC? For another words, can I fix the nitrogen deposition in CLM-BGC when I use CAM-Chem (eg. fix the nitrogen depostion in 1850)?

 

[oleson]

I am not sure. I think that CAM-Chem provides the nitrogen deposition through the following in drv_flds_in:

&ndep_inparm
ndep_list = 'noy', 'nhx'
/

So I think you'd have to turn this off somehow so that CLM uses the Ndep stream instead. You could post on the CAM Forum and see if this has been done before.

 

[Yuexuanzi Wang]

I am not sure. I think that CAM-Chem provides the nitrogen deposition through the following in drv_flds_in:

&ndep_inparm
ndep_list = 'noy', 'nhx'
/

So I think you'd have to turn this off somehow so that CLM uses the Ndep stream instead. You could post on the CAM Forum and see if this has been done before.

I have tried to modify the ndep_list, and it finally worked! Thanks for solving my problems!