overlaying gridded data

Hello NCL users,

  I am working on building an overlay plot of two gridded variables (no lat
and lon coordinates). The first variable (u-component wind) is on a grid
that is 200(j) x 320(i) cells. My second variable is on a grid that is
2000(j) x 3200(i) cells. Both variables represent the output for a model
domain that is 5km x 8km in size. Because the i and j indices for these
two variables don't match, I am not getting an accurate overlay of variable
2 onto variable 1. I think I may need to use the Transform resources to
force one of these variables to be the same size as the other, but I am not
completely sure of this and could use both some advice, and possibly an
example to look at. Here is my NCL code so far (there is currently no
transformation present):

;================================================;
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
;================================================;

begin

;=================================================;
; open file and read in data
;=================================================;

  K = 1
  Plot = "x11"
  T1 = 15
  T2 = 18
  T3 = 25
  T4 = 35
  Title = "Fire Area"
  File = "base_unstable_60A"
  FileT= "Fire_Area_"+File

  f =
addfile("/mnt/pvfs2/karay/Rath_SA/StabilitySound_xy4/"+File+"/wrfout_d01_2006-02-23_12:00:
00.nc","r")

  Fa1 = f->FIRE_AREA(T1,:,:) ; fraction of cell area on fire
  Fa2 = f->FIRE_AREA(T2,:,:)
  Fa3 = f->FIRE_AREA(T3,:,:)
  Fa4 = f->FIRE_AREA(T4,:,:)

  ua = wrf_user_getvar(f,"ua",-1) ; umet and vmet averaged to mass
points
  U1 = ua(T1,K,:,:)
  U2 = ua(T2,K,:,:)
  U3 = ua(T3,K,:,:)
  U4 = ua(T4,K,:,:)

;=================================================;
;plotting resources set
;=================================================;

  wks = gsn_open_wks(Plot,FileT)
  plot_u = new(4,graphic)
  plot_o = new(4,graphic)
  plot = new(4,graphic)

  gsn_define_colormap(wks,"hotres") ; choose a colormap used hotres
before
  res = True ; plot mods desired
  res@lbLabelBarOn = False ; turn off individual label bars
  res@cnLineLabelsOn = False
  res@cnInfoLabelOn = False
  res@gsnDraw = False ; don't draw
  res@gsnFrame = False ; don't adnvance frame
  res@cnFillOn = True ; turn on color
  res@gsnSpreadColors = True ; use full range of colormap
  res@cnLinesOn = False ; turn off contour lines
  res@lbLabelAutoStride = True ;
  res@vpWidthF = 0.8 ; change aspect ratio of plot
  res@vpHeightF = 0.4
  res@lbLabelAngleF = 45 ; angle labels
  res@lbLabelFontHeightF =.022 ; make labels larger
  res@lbTitleOn = True ; turn on title
  res@lbTitleFontHeightF = .015 ; make title smaller
  res@pmLabelBarOrthogonalPosF = .10 ; move whole thing down

  sres = True
  sres@gsnDraw = False
  sres@gsnFrame = False
  sres@cnLineThicknessF = 2.
  sres@tfDoNDCOverlay = True
;===============================================================================
; Make plots
;===============================================================================

  plot_o(0) = gsn_csm_contour(wks,Fa1,sres)
  plot_u(0) = gsn_csm_contour(wks,U1,res)
  overlay(plot_o(0),plot_u(0))
  plot(0) = plot_o(0)

  plot_o(1) = gsn_csm_contour(wks,Fa2,sres)
  plot_u(1) = gsn_csm_contour(wks,U2,res)
  overlay(plot_o(1),plot_u(1))
  plot(1) = plot_o(1)

  plot_o(2) = gsn_csm_contour(wks,Fa3,sres)
  plot_u(2) = gsn_csm_contour(wks,U3,res)
  overlay(plot_o(2),plot_u(2))
  plot(2) = plot_o(2)

  plot_u(3) = gsn_csm_contour(wks,U4,res)
  plot_o(3) = gsn_csm_contour(wks,Fa4,sres)
  overlay(plot_o(3),plot_u(3))
  plot(3) = plot_o(3)

;===============================================================================
; Creat Panel
;===============================================================================

  resP = True
  resP@txFontHeightF = 0.03
  resP@gsnFrame = False ; don't
advance panel plot
  resP@txString = "Surface Winds "+File ; add
common title
  resP@gsnPanelBottom = 0.01 ; add space
at bottom
  resP@gsnPanelFigureStrings = (/"t = "+T1,"t = "+T2,"t =
"+T3,"t = "+T4/) ; add strings to panel
  resP@amJust = "BottomRight"
  resP@gsnPanelFigureStringsFontHeightF = 0.015 ; set string font
size
  resP@gsnPanelLabelBar = True ; set common label
bar
  resP@gsnPanelFigureStringsPerimOn = True ; turn off box
around annotation
  resP@gsnPanelXWhiteSpacePercent = 5 ; set a bit of
extra white space between panels in the x and y directions
  resP@gsnPanelYWhiteSpacePercent = 5
  resP@gsnPaperOrientation = "landscape"

  gsn_panel(wks,plot,(/2,2/),resP)

  txres = True
  txres@txFontHeightF = 0.015
  gsn_text_ndc(wks,Title,0.5,0.02,txres)

  frame(wks)

end

Thank you for your help,
Kara

-- 
"Don't knock the weather; nine-tenths of the people couldn't start a
conversation if it didn't change once in a while."  ~Kin Hubbard

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Received on Thu May 24 17:13:17 2012