Initializing a passive tracer

[kwerner]

You'll need to set tracer_opt = 2 in the namelist (&dynamics). When you run the real.exe program, it initializes 8 tracers in a 9x9 grid area, centered in the domain. If you would like to initialize the tracers in other locations, you can modify the real program (module_initialize_real.F) directly or overwrite the initialized tracers in start_em.F.