wmlabs in loop plots symbols at wrong positions

Hello.

I am trying to use the wmlabs procedure to plot dot symbols on a
map. I am outputting multiple frames, so gsn_csm_contour_map_ce and
wmlabs are called within a loop. I am following roughly the NCL
sample program weather_sym_4.ncl.

In the first frame, the dots plot at the expected coordinates.
However, in the second frame, the dots plot at completely unexpected
positions. They are still in the same relative positions, but the
scale and origin of the X and Y coordinates have been shifted. In
subsequent frames, the dots remain in the same incorrect positions.

The problem goes away when gsn_csm_map is substituted for
gsn_csm_contour_map_ce. But I need the contour function to show my
data over the base map.

Can anyone tell me what the problem is? Attached is a demo script.
  Any input file with gridded data on (lat, lon) coordinates should
work. Thank you.

NCL version = 4.2.0.a034
uname -a output:
Darwin mac56.cdc.noaa.gov 8.8.0 Darwin Kernel Version 8.8.0: Fri Sep
  8 17:18:57 PDT 2006; root:xnu-792.12.6.obj~1/RELEASE_PPC Power
Macintosh powerpc

--Dave A.
CU/CIRES Climate Diagnostics Center (CDC)
NOAA/ESRL/PSD, Climate Analysis Branch (CAB)

;-----------------------------------------------------------------------------
;
; Sample program to print dot symbols on top of plots.
;
; 2007-feb-03 By Dave Allured and Brant Liebmann.
; Simplified version to debug problem with dot positions.
;
;-----------------------------------------------------------------------------

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin

; Parameters.
  
  infile = "/data/bl/rain/grid/na1.daily.2.5.1940-2004.nc"

  output = "x11" ; x11=window, ps or eps or epsi=postscript, pdf=PDF
  outfile = "dots.example.0203"

; Read input file.

  in = addfile (infile, "r")
  pgrid = in->precip(1,:,:) ; read a single (lat, lon) array

; Create plot.

  print ("Plot setup.")
  wks = gsn_open_wks (output, outfile) ; open output file or x11 window
  gsn_define_colormap (wks, "testcmap")
  
  res = True ; plot mods desired

  res_at_gsnFrame = False ; hold frame to draw dots on top of plot

  res_at_cnFillOn = True ; turn on color fill
  res_at_cnLinesOn = False ; turn off contour lines
  
  res_at_gsnSpreadColors = True ; choose colors across entire range
  res_at_gsnSpreadColorStart = 5

  res_at_mpFillOn = False ; turn off gray continents

  res_at_gsnMaximize = True ; make figure fit in frame properly
  res_at_gsnPaperOrientation = "portrait"
  
  res_at_gsnAddCyclic = False

  res_at_mpMinLonF = -120 ; temporary plot boundaries for
  res_at_mpMaxLonF = 60 ; diagnosing wmlabs() dot problem
  res_at_mpMinLatF = -80
  res_at_mpMaxLatF = 80

  res_at_mpCenterLonF = (res_at_mpMinLonF + res_at_mpMaxLonF) / 2

  res_at_mpOutlineBoundarySets = "geophysicalandusstates"; turn on states
  res_at_mpDataBaseVersion = "mediumres" ; select database
  res_at_mpDataSetName = "Earth..2"

; Loop for multiple plots for different dates.

  do nr = 20, 22

    plot = gsn_csm_contour_map_ce (wks, pgrid, res) ; create base plot

    wmsetp ("ezf", 1) ; Tell wmap we are using an existing map projection

    wmsetp ("DTS", 0.015) ; DoT Size (fraction of screen height)
    wmsetp ("DBC", 200) ; Dot Bottom Color index (outer ring)
    wmsetp ("DTC", 60) ; Dot Top Color index (main center)
                                        ; for solid dot, make DBC = DTC

    lats = (/ 18., 28.5, 31. /) ; one or more latitudes
    lons = (/ -98., -107.0, -99. /) ; one or more longitudes
    wmlabs (wks, lats, lons, "DT") ; draw dot symbols on top of plot

    frame (wks) ; print final plot to window or output file

  end do
  
end

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Received on Sat Feb 03 2007 - 21:41:37 MST