I.14.2. ->ZONA - Zonal averaging
 
                  
 Primary ICPs:   [ZONAVG]
 
 Secondary ICPs: <ZAVGDSP> <ZAVRNG> <ZBKFR> <ZAVGPRN>
 
   When zonal averaging is requested [ZONAVG], all levels of all fields are
averaged along each latitude line with all longitudes weighted equally.
Processing then continues, with subsequent operations using either the zonal
averages or the unaveraged data <ZAVGDSP> as a starting point (*SPAV) (*ORDR).
An arbitrary longitude range for the averaging may be specified <ZAVRNG>, and
the minimum fraction of unblocked points used to compute each average may be
controlled <ZBKFR>. The averages may also be printed in the output file
<ZAVGPRN>.  When computed, zonal averages may be plotted as meridional cross
sections (*PMEX) <ZAVGDSP>. Plot characteristics can be controlled through the
use of the appropriate ICPs (*PLOT).
 
   Zonal averages cannot be computed more than once on the same data; if the
averages are written to a Save Tape (*SAVT), vertical cross-section plots may
be requested in subsequent runs with the ICP <MXPLOT>.