Hi all,
I am running a 3-domain nested WRF-ARW case over Lagos using ERA5 forcing. The model repeatedly crashes around 2022-02-23 12:43-12:44 UTC.
Earlier tests around the same time/location produced CFL-related errors like:
points exceeded cfl=2 in domain d01
After reducing the timestep, the CFL errors no longer appear, but the model still crashes at nearly the same simulation time.
To investigate this, I restarted the run shortly before the crash with wrf.exe of debug version. The crash appears to occur in Thompson microphysics, around the condensation iteration involving:
fcd = qvs(k)*EXP(lvt2(k)*clap) - qv(k) + clap
I then added a local diagnostic guard before this EXP() call, so that the model stops before the original floating overflow and prints the relevant values. This diagnostic is not a native WRF message. It was only added locally to help identify the problematic grid point and variables.
The diagnostic output is:
THOMPSON EXP overflow risk ii,jj,k,n= 112 60 2 1
qv,qvs,ssatw,clap,lvt2,arg=
3.473003 1.7083695E-03 2031.934 3.188251 51.96595 165.6805
The very large qv and supersaturation suggest that the immediate failure is an overflow in the Thompson condensation iteration. The last normal history output before the crash does not show obvious NaN/Inf values.
My question is: what is the recommended way to handle this kind of failure? Since reducing the timestep removed the CFL warning but did not prevent the crash, should I continue reducing the timestep, adjust nest feedback/smoothing, modify the domain/nesting setup, or switch microphysics schemes?
The namelist.input and relevant rsl.error/rsl.out files are attached. Any suggestions for diagnosing or stabilizing this case would be appreciated.
I am running a 3-domain nested WRF-ARW case over Lagos using ERA5 forcing. The model repeatedly crashes around 2022-02-23 12:43-12:44 UTC.
Earlier tests around the same time/location produced CFL-related errors like:
points exceeded cfl=2 in domain d01
After reducing the timestep, the CFL errors no longer appear, but the model still crashes at nearly the same simulation time.
To investigate this, I restarted the run shortly before the crash with wrf.exe of debug version. The crash appears to occur in Thompson microphysics, around the condensation iteration involving:
fcd = qvs(k)*EXP(lvt2(k)*clap) - qv(k) + clap
I then added a local diagnostic guard before this EXP() call, so that the model stops before the original floating overflow and prints the relevant values. This diagnostic is not a native WRF message. It was only added locally to help identify the problematic grid point and variables.
The diagnostic output is:
THOMPSON EXP overflow risk ii,jj,k,n= 112 60 2 1
qv,qvs,ssatw,clap,lvt2,arg=
3.473003 1.7083695E-03 2031.934 3.188251 51.96595 165.6805
The very large qv and supersaturation suggest that the immediate failure is an overflow in the Thompson condensation iteration. The last normal history output before the crash does not show obvious NaN/Inf values.
My question is: what is the recommended way to handle this kind of failure? Since reducing the timestep removed the CFL warning but did not prevent the crash, should I continue reducing the timestep, adjust nest feedback/smoothing, modify the domain/nesting setup, or switch microphysics schemes?
The namelist.input and relevant rsl.error/rsl.out files are attached. Any suggestions for diagnosing or stabilizing this case would be appreciated.