NOTE: This routine was only used in the early days of the wet depositions scheme and is now redundant!

This script will cycle through a list of WRF output files given as arguments
and calculate the hourly precipitation.

Example:
  python flx_ppwrf.py file1 file2 [...fileN]

  Will calculate the average precipitation rate over the last hour.
  the files can only contain one output time. The time between files
  must be one hour.

The created variables are:
  PRECIP_H          -     Large scale precipitation
  PRECIP_H_CONV     -     Convective precipitation


Current problems:
* Precipitation rate will be for the past hour not current time