For a bit more information on memory usage, we've generally found that providing about 0.175 MB of memory per grid column (with 55 vertical layers) is adequate when running the model itself (i.e., the atmosphere_model program). The initialization program requires less memory because it allocates fewer fields; I don't have a good figure, but just guessing wildly, it may be that the init_atmosphere_model program requires only half the memory of the model. For a mesh with 535554 columns, then, you might want to ensure that you have at least 535554 * 0.175 MB = 93.7 GB of aggregate memory when running a model simulation, and the initialization of the model might require around 46 GB. Although most of the Cheyenne batch nodes have 64 GB of memory, not all of this is available to user processes. So, using at least a couple of nodes when creating the initial conditions, and using more nodes still when running the model is probably good.