[cam-users] CAM blow-up

[Ragoth Sundararajan]

hi,

I am running CAM at a higher vertical resolution. This worked for several 
runs so far, but the present run seems to blow up in the following way:

NSTEP =   32121   8.935174808223684E-05  7.179735399927720E-06 
250.900  9.84382E+04  2.204584220356811E+01 0.72  1.13
  NSTEP =   32122   8.937561785090568E-05  7.387377207262184E-06 
250.899  9.84382E+04  2.204539090829577E+01 0.75  1.11
  NSTEP =   32123   8.942472814784718E-05  7.950277355457169E-06 
250.899  9.84382E+04  2.204453809698432E+01 0.90  1.26
  NSTEP =   32124   8.953576120359026E-05  9.358443771738252E-06 
250.899  9.84382E+04  2.204432375119116E+01 1.16  1.48
  SPHDEP: ****** MODEL IS BLOWING UP *********


Parcel associated with longitude    60, level    37 and latitude    49 is 
outside the model domain.
  ENDRUN IS BEING CALLED
  CUBYDR: Departure point out of bounds: jcen,icount,nlon*plev= 53 6015 6016
  ENDRUN IS BEING CALLED

I see that the courant number (vertical) is consistently above unity in the 
last several time steps, and when the horizontal courant number also 
catches up to unity, the model blows up (It's strange the way this number 
jumps up to unity in a couple of time steps). Does this mean, reducing the 
time step is the only solution ? I have run a few other cases with higher 
vertical resolution with 1200 sec time step, and they worked (although 
courant number violation occurred there also, but no blow up).

Any ideas will be appreciated. Thanks in advance.

Ragoth Sundararajan.
MIT.