negative wet deposition flux of sulfate?

[m6lin@ucsd_edu]

I am working on the data downloaded from ACCMIP (The Atmospheric Chemistry and Climate Model Intercomparison Project). I found that the wet_SO4 in San Diego area in both CAM3.5 and 5.1 are negative. I was wondering what the negative value means. If I want to calculate the lifetime of sulfate, how should I do with these negative data? Thanks.

 

[alcide_zhao@ed_ac_uk]

Hi lin, I wonder if you have got this issue resolved?  Do we need also to ake account for dry deposition?  Cheers, Alcide  

 

[alcide_zhao@ed_ac_uk]

Hi lin, I wonder if you have got this issue resolved?  Do we need also to ake account for dry deposition?  Cheers, Alcide  

 

[m6lin@ucsd_edu]

We believed that those data should be positive. I forgot about dry deposition but I think they are positive.

 

[m6lin@ucsd_edu]

We believed that those data should be positive. I forgot about dry deposition but I think they are positive.

 

[hyf412694462]

Hello m6lin and zhao,

Have you solved this question? When I conduct experiments using CLM5 (--compset I1850Clm50BgcCrop), I checked the input data of N deposition (fndep_clm_hist_b.e21.BWHIST.f09_g17.CMIP6-historical-WACCM.ensmean_1849-2015_monthly_0.9x1.25_c180926.nc).

I found part (within Antarctic) of the wet deposition flux of NHx in the above .nc file is negative. I think negative fluxes are not physically realistic, but they are very small (10^-30) and may not significantly impact the overall results of the model. I just wonder what the negative values means? Is it reasonable or caused by some bugs in WACCM? How should I treat those negative values, should I just zeroing those negative values?

I would like to appreciate any information you could provide.

 

[peverley]

Moving this to the WACCM forum in the hopes they can answer your question.

 

[hyf412694462]

Dear Peverley,

Thanks a lot for your message. You can move my message to WACCM forum. Have you did this?

 

[rrbuchholz]

Hi there,
Wet deposition values are negative in the atm history files because the species are removed from the atmosphere.
In the lnd history files wet deposition values are positive because wet deposition adds to the land model component.
Cheers,
Rebecca