Re: [want real z-axis]Re: [ferret_users] change axis

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Chan Joo,
I was wrong before when I said that ZAXREPLACE wouldn't allow the second 
argument to vary in time.  It does.  Here is a script that works with 
the ARGO data. I'll put together an FAQ on this, as it'll be of general 
interest.

In the figure are the pressure and temperature fields on the left, and 
the regridded temperature-on-pressure field to the right.

It's important to define a fixed pressure axis for the result of the 
zaxreplace definition, rather than using a profile from a dataset, 
because a particular profile in a dataset may have missing data, and 
also because it makes the data consistent and comparable from one file 
to another. I made a list of pressures from one of the files, and 
rounded off the values to the nearest 5 or 10 or 100 and so on.



! USE/ORDER=ZT 2900623_prof.nc
USE/ORDER=ZT2900622_prof.nc

! Define a time axis based on JULD

DEF AXIS/T/T0="1-JAN-1950:00:00"/UNITS=days tday=juld

LET zz=Z[GZ=temp]
DEF AXIS/Z/UNITS=levels/DEPTH zlev=zz

! Put the temperature and pressure on this corrected time-layer grid

LET/UNITS="`pres,R=units`"/TITLE="`pres,R=title`"/BAD=`pres,R=bad` \
   pressure=pres[gz=zlev@asn,gt=tday@asn]

LET/UNITS="`temp,R=units`"/TITLE="`temp,R=title`"/BAD=`temp,R=bad` \
   temperature=temp[gz=zlev@asn,gt=tday@asn]

SET VIEW ul
SHADE pressure
SET VIEW ll
SHADE temperature

! Define an output Z axis with units of pressure.

DEFINE AXIS/Z/UNITS=decibars/DEPTH zpres= {5.,10.,15.,20.,25.,30.,34.,40.\
,45.,50.,55.,60.,65.,70.,75.,80.,85.,90.,95.,100.,105.,110.,120.,130.,\
140.,160.,180.,200.,225.,250.,275.,300.,325.,350.,375.,400.,450.,500.,\
550.,600.,675.,750.,825.,900.,1000.,1100.,1200.}

! Call zaxreplace to put the temperature data on this new pressure axis

LET/UNITS="`temperature,R=units`"/TITLE="`temperature,R=title`" \
   temp_on_pres=ZAXREPLACE(temperature,pressure,Z[GZ=zpres])

SET VIEW ur
SHADE temp_on_pres