1.6.2. Running a single point using global data - PTS_MODE

PTS_MODE enables you to run the model using global datasets, but just picking a single point from those datasets and operating on it. It can be a very quick way to do fast simulations and get a quick turnaround.

To setup a PTS_MODE simulation you use the “-pts_lat” and “-pts_lon” arguments to create_newcase to give the latitude and longitude of the point you want to simulate for (the code will pick the point on the global grid nearest to the point you give. Here’s an example to setup a simulation for the nearest point at 2-degree resolution to Boulder Colorado.

> cd scripts
> ./create_newcase -case testPTS_MODE -res f19_g17_gl4 -compset I1850Clm50BgcCropCru -pts_lat 40.0 -pts_lon -105
> cd testPTS_MODE

# We make sure the model will start up cold rather than using initial conditions
> ./xmlchange CLM_FORCE_COLDSTART=on,RUN_TYPE=startup

Then setup, build and run as normal. We make sure initial conditions are NOT used since PTS_MODE currently CAN NOT run with initial conditions.


PTS_MODE currently does NOT restart nor is it able to startup from global initial condition files. This is a known issue we are unlikely to fix.


You can change the point you are simulating for at run-time by changing the values of PTS_LAT and PTS_LON in the env_run.xml file. Running in a single processor

Note, that when running with PTS_MODE the number of processors is automatically set to one. When running a single grid point you can only use a single processor. You might also want to set the env_build.xml variable: MPILIB=mpi-serial to TRUE so that you can also run interactively without having to use MPI to start up your job.

On many machines, batch queues have a minimum number of nodes or processors that can be used. On these machines you may have to change the queue and possibly the time-limits of the job, to get it to run in the batch queue. On the NCAR machine, cheyenne, this is done for you automatically, and the “share” or “caldera” queue is used for such single-processor simulations. For single point mode you also may want to consider using a smaller workstation or cluster, rather than a super-computer, because you can’t take advantage of the multi-processing power of the super-computer anyway.