very high soil respiration at 3-hour scale?

[zhenlinyoung@gmail_com]

I am running clm-cn 4.5 with my own 3-hourly, 1/24th degree data for western US.In the output, GPP looks fine, but the soil respiration goes very high in forested area. even higher than gpp, leading to negative NEP, which is not right in my study region. the log file says many errors such as:Negative conc. in ch4tran. c,j,deficit (mol):        19146            1
   4.5597589192627290E-003
 Note: sink > source in ch4_tran, sources are changing quickly relative to diffusion timestep, and/or diffusion is rapid.
 Latdeg,Londeg=    45.35420000000000         241.4375000000000    
 This typically occurs when there is a larger than normal diffusive flux.
 If this occurs frequently, consider reducing land model (or methane model) timestep, or reducing the max. sink per timestep in the methane model. I have the methane module turned on. Does anyone have some ideas about the reason behind?

 

[aresovsk@gmail_com]

Hi Zhenlin,I am having the same problem running the methane model. I get zero or negative CH4 fluxes over most of the world, and when I check the lnd log file, I see the same error you are seeing. I see this post is quite old... Did you ever get the problem fixed? If so, how? Did you try the suggestions given in the log ("consider reducing land model (or methane model) timestep, or reducing the max. sink per timestep in the methane model.")?  I have not attempted either of these solutions yet.