;
pro rd2d
;
; Open a tgcm history and read a 2-d lat,lon field:
;
; ncfile: name of history file to read:
;
ncfile = "FESEN.tiegcm1.marcond2.nc"
;
; var2d: name of 2-d field to read from ncfile:
;
var2d = "ZIGM11"
;var2d = "trash"

;
; Open the file, and inquire:
;
on_ioerror,badfile
cdfid = ncdf_open(ncfile)
print,'Opened file ',ncfile,' cdfid=',cdfid
file_inq = ncdf_inquire(cdfid)
;help,file_inq,/struct
;
; Search for variable var2d:
;
for ivar = 0,file_inq.nvars-1 do begin
  var = ncdf_varinq(cdfid,ivar)
  if var.name eq var2d then begin
    found = 1
    print,'Found variable ',var2d
;   help,var,/struct 
    id = ivar
    goto,found
  endif
endfor
print,' ' & print,'>>> Could not find variable ',var2d,' on file ',ncfile
return
found:
;
; Confirm that variable is 3d (2d in space, one in time)
;
var = ncdf_varinq(cdfid,id)
if var.ndims ne 3 then begin
  print,' '
  print,'>>> Variable ',var2d,' is not 3-d (2-d in space, 1 in time): ',$
    'var.ndims=',var.ndims
  return
endif
dimnames = strarr(3)
dimsizes = intarr(3)
for idim = 0,var.ndims-1 do begin
  ncdf_diminq,cdfid,var.dim(idim),dimname,dimsize
  dimnames[idim] = dimname
  dimsizes[idim] = dimsize
endfor
print,format="('Variable ',a,' is dimensioned (',3a8,') where:')",var2d,dimnames
for i=0,2 do print,'  ',dimnames[i],' = ',dimsizes[i]
;
; Read the variable. It will be vardat[dimsizes[0],dimsizes[1],dimsizes[2])
;
ncdf_varget,cdfid,id,vardat
help,vardat
;
; Print var at time 1 (2nd time):
;
for j=0,dimsizes[1]-1 do begin
  print,var2d,': j=',j,' vardat[*,j,1]='
  print,vardat[*,j,1]
endfor
;
; Here you could write the var to a formatted file, or do whatever with it... 
;


return
badfile:
  print,'>>> Error opening file ',ncfile
  return
end