lnd_import ERROR: Longwave down sent from the atmosphere model is negative or zero

[BoHuang]

Dear all,
recently, I am working on CAM6 with variable-resolution simulation. I want to run the simulation with FHIST_BGC component set. I build the model and can successfully complete the the simulation for 5 days (STOP_N=5). However, the model always crash when I change the STOP_N to a longer time. The error occurs at time-step 1241 (dtime=450s), as "lnd_import ERROR: Longwave down sent from the atmosphere model is negative or zero". I already contacted to CLM community. They think that this error is from CAM. I have no idea how this error comes? Is there any one have idea how to fix it? Enclosed the log files. Thank you.

Greetings
Bo

 

[aherring]

Bo, can you verify that nu_s = nu_p in src/dynamics/se/dycore/global_norms_mod.F90

 

[BoHuang]

Hi Adam,

I confirm it. src/dynamics/se/dycore/global_norms_mod.F90 line 567-577

if (nu_q<0) nu_q = nu_p ! necessary for consistency
if (nu_s<0) nu_s = nu_p ! temperature damping is always equal to nu

 

[aherring]

Bo, lets take this conversation offline since this is related to developmental code.

 

[ShirleyX]

Hi Bo,
Have you solved this problem?
I also encountered the same problem when I used THE CLM_BGC-CROP again when I did the step of "final" acceleration model.

 

[aherring]

What --res are you running? what code base?

 

[ShirleyX]

Hi Adam.
I have solved the problem.The reason for the error is that there is a long-wave radiation error in my weather-driven data.

 

[zhendf]

Bo, lets take this conversation offline since this is related to developmental code.

Hi, Adam
I just use the tools GitHub - NCAR/Topo: NCAR Global Model Topography Generation Software for Unstructured Grids to generate TRUE topography for the VR-grid, but I found that I can't find the key file "/glade/p/cgd/amp/aherring/grids/topo/gmted2010_modis-ncube3000-stitch.nc", Could you please tell me how to download this file? I don't have a NACR/UCAR account, Or Could you please send this file to my email, my email is zhengdf@mail2.sysu.edu.cn.

Thanks!

 

[zhendf]

Bo, lets take this conversation offline since this is related to developmental code.

I make some mistake, maybe is the file glade/p/cgd/amp/aherring/grids/topo/cubedata/gmted2010_bedmachine-ncube3000.nc

 

[aherring]

check your email

 

[pybl]

I got the same error message,

I use WACCM 6 --compset BWma1850 --res f19_g17 for my simulation and STOP_N= 6 months, and I changed orbital configuration which caused the global mean temperature to increase, and I doubled dt_count = 48 in user_nl_pop . The simulation case successfully run for 16 years before it encountered this error shown in cesm log file that stopped the run.

'' lnd_import ERROR: Longwave down sent from the atmosphere model is negative or zero ''

Any help is appreciated!

 

[katec]

Hi there. As you can see from this thread, the model gets this error for a lot of different reasons, and it is really just a sign that the atmosphere has gotten into an unstable state and is crashing. How did you change your orbital parameters? I have seen some modifications to orbitals that use the wrong versions of files in source_mods and that causes a problem with ocean albedos not being correct. I would double check that your source mod files do not make any changes beyond the orbital parameters that you expect. And I would look at your history files to try and find what is causing the instability. Are surface temperatures going too high? Is the top of the atmosphere radiation imbalance too large? Are clouds too thick causing long wave radiation problems?

 

[pybl]

Hi there. As you can see from this thread, the model gets this error for a lot of different reasons, and it is really just a sign that the atmosphere has gotten into an unstable state and is crashing. How did you change your orbital parameters? I have seen some modifications to orbitals that use the wrong versions of files in source_mods and that causes a problem with ocean albedos not being correct. I would double check that your source mod files do not make any changes beyond the orbital parameters that you expect. And I would look at your history files to try and find what is causing the instability. Are surface temperatures going too high? Is the top of the atmosphere radiation imbalance too large? Are clouds too thick causing long wave radiation problems?

Thanks for the reply!

I am doing an experiment that only changes orbital eccentricity = 0.4 and orbital obliquity = 0, and the top of model energy imbalance is about 10 w/m^2 after running for 16 years. I also expect the surface temperature to increase. I see I am pushing the model to the edge of instability, but I am wondering if changing the timesteps in user_nl_cam could fix the problem (the model would slow down of course), Also, can you explain what you mean by "surface temperature too high, energy imbalance too large and clouds too thick" --- what are the thresholds to these three parameters?

Thanks again for helping!