function findvarname,ddtype,spnum,spec
;+
;   Function findvarname is called by read_combo.pro. It uses the file datatype (e.g.
;	 'idaily' or 'amonthly' or 'overpass2') and the species number to figure out
;	what variable this species is called by in the netcdf file. For example, daily
;	O3 is stored in the variable 'const_freq1'. Temperature in the overpass files
;	is stored in 'kel_overpass'. Variable name is returned.
;
;	Modified 4/21/08 by SES
;
;-

;	'ddtype' has 8 possibililties. For each one (a data type), there are several
;	possible variable names. Use 'spec' to figure this out.

fdtype=['amonthly','idaily','overpass1','overpass2','overpass3','overpass4','hourlyoz','column','rst']

;	Monthly Average
if ddtype eq fdtype(0) or ddtype eq fdtype(8) then begin
   if spnum gt 0 and spnum lt 125 then varname='const'
   if spnum eq 126 then varname='kel'
   if spnum eq 125 then print, 'No monthly potential vorticity available.'
endif

;	Daily instantaneous
if ddtype eq fdtype(1) then begin
;   if spnum ge 1 and spnum le 13 then varname='const_freq1'
;   if spnum eq 14 then varname='potentialVorticity_freq1'
;   if spnum eq 15 then varname='kel_freq1'
    varname='const_freq1'
    if spec eq 'TEMP' then varname='kel_freq1'
    if spec eq 'PV' then varname='potentialVorticity_freq1'
endif
 
;	Overpass1
if ddtype eq fdtype(2) or ddtype eq fdtype(3)  or ddtype eq fdtype(4) or ddtype eq fdtype(5) then begin
   if spnum ge 1 and spnum le 6 then varname='const_overpass'
   if spnum eq 7 then varname='kel_overpass'
endif

if ddtype eq fdtype(6) then print, 'Hourly Ozone is not readable at this time.'

if ddtype eq fdtype(7) and spnum le 3 then varname='constColTrop_freq3'
if ddtype eq fdtype(7) and spnum gt 3 then begin
  varname='constColCombo_freq3'
  spnum=spnum-3
endif

return,varname

end