Questions about N2O emission

[zhangjkstrato@hotmail_com]

I am investigating the influence of N2O emission in East Asia on stratospheric ozone. I want to design an experiment with an increase in N2O emission by using WACCM. I want to ask whether the module "waccm_mozart" uses independent N2O emission. I only found the module "trop_mozart" uses it but "waccm_mozart" only has N2O data in LBC_Scen data. I am looking forward to your reply. Thank you very much.

 

[mmills]

WACCM specifies the lower boundary condition for N2O as a time-varying zonal-average mixing ratio. From what I can tell, CAM4-chem also uses a mixing ratio LBC for N2O. Where in trop_mozart do you see N2O emissions specified?

 

[zhangjkstrato@hotmail_com]

Hi mmills, I found there is definitely N2O emission to force "trop_mozart" module and the data path is /***/waccm/inputdata/atm/cam/chem/trop_mozart/emis/emis.n20.nc. I also checked the Fortran code (mo_srf_emissions.F90 Line 312)and found the n2ovmr read from emis_file_in is a 3-D array.  I compiled and run the "trop_mozart" with N2O emission successfully. But the number of vertical levels is only 26, not enough to capture the stratosphere. Therefore, I have to use the "waccm_mozart" module. I am thinking whether it is possible to use a N2O emission with longitude varies to replace the constant values in LBC_Sce data. The sensitive experiment adopts 12-month cycle.  

 

[mmills]

Okay. I believe that you can do this by simply modifying your namelist. You can add N2O to the surface emissions and remove it from the LBC list in the namelist. Look at the CAM-chem namelist as a model. Make your namelist changes by putting them in user_nl_cam in your case directory. Let me know how it goes. 

 

[zhangjkstrato@hotmail_com]

Hi, mmills. I use WACCM3 and it does not have "user_nl_cam". But I modified the Fortran codes, including chemistry.F90, mo_srf_emission.F90, mo_chemini.F90 and chem_surfvals.F90 and added variables regarding on n2o_emis into these programs. All of them locate in the directory "waccm_mozart". Finally, the modified codes run sucessfully. The first day's output of N2O near the surface and n2o_emission are in attachment and they are alike to each other in the regions with high N2O emitted. Jiankai 

 

[zhangjkstrato@hotmail_com]

Hi, mmills. I use WACCM3 and it does not have "user_nl_cam". But I modified the Fortran codes, including chemistry.F90, mo_srf_emission.F90, mo_chemini.F90 and chem_surfvals.F90 and added variables regarding on n2o_emis into these programs. All of them locate in the directory "waccm_mozart". Finally, the modified codes run sucessfully. The first day's output of N2O near the surface and n2o_emission are in attachment and they are alike to each other in the regions with high N2O emitted. Jiankai 

 

[mmills]

I have talked with Simone Tilmes, who is the community liaison for CAM-chem. She confirmed that CAM-chem uses a mixing ratio LBC for N2O, just like WACCM. Someone may have tried setting up an emission file for N2O, but it is not in any supported compsets. You can try setting this up on your own; we do not have resources at NCAR to support this, or WACCM3.

 

[zhangjkstrato@hotmail_com]

Thank you very much. I've got it.Jiankai