As a user, I would like to summarize statistics across pools

[HankHerr-NOAA]

See conversation in this comment and the comments that follow.

This ticket can be resolved when we are able to declare that summary statistics are to be computed across all pools; for example, something like:

summary_statistics:
  statistics: 
    - mean
    - standard deviation
  dimensions:
    - pools

Thanks,

Hank