叠加画图时总有张图无法显示指定区域的问题

dongjunhui11

初学ncl画图 想画形势图 问题是等温线和等高线合在一起时候
指定经纬度的那四个res是只有在gsn_csm_contour_map有map的情况下才能生效吗？
我的程序里plot_ov等温线后面没有跟map 画等高线的plot有map
所以就会出现出图时等高线显示正常但等温线不是显示的指定经纬度区域而出现叠加错位的问题
请问各位大神 怎么解决这个问题 另外我出图时总会多有一张全白的图是怎么回事？
谢谢各位！以下是我的程序

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"

begin
  lat_tulufan = 42.0  
  lon_tulufan = 88.0

f    = addfile("hgt.2013.nc","r")
t    = addfile("air.2013.nc","r")

  u = f->hgt(784,{500},:,:)  
  v = t->air(784,{500},:,:)

  hgt1 = u/10            
  temp  = v-273

  wks = gsn_open_wks("png","2013-07-16-00-Cirsituation.500hpa")

  res = True
  res@gsnDraw   = False
  res@gsnFrame  = False
  res@mpMinLatF   = 20     
  res@mpMaxLatF   = 70
  res@mpMinLonF   = 30
  res@mpMaxLonF   = 120
  res@mpOutlineOn  = True

  res@tiMainString = "2013-07-16-00-Cirsituation.500hpa"  


  res@cnLevelSelectionMode = "ManualLevels"
  res@cnLevelSpacingF = 4



  sres = True
  sres@gsnDraw = False
  res@gsnFrame  = False
  sres@cnMonoLineColor = True

  sres@cnLineColor = "red"

  plot = gsn_csm_contour_map(wks,hgt1,res)
  plot_ov = gsn_csm_contour(wks,temp,sres)   

   overlay(plot,plot_ov)

   mkres               = True   
   mkres@gsMarkerColor = "black"
   mkres@gsMarkerSizeF = 0.02
   mkres@gsMarkerIndex = 1

   dum1  = gsn_add_polymarker(wks,plot,lon_tulufan,lat_tulufan,mkres)


  txres                 = True
  txres@txFontHeightF   = 0.015
  txres@txFontColor     = "black"
  dum2 = gsn_add_text(wks,plot,"Tulufan",lon_tulufan,lat_tulufan+3.0,txres)



  draw(plot)
  frame(wks)

  end

dongjunhui11

(0)     check_for_y_lat_coord: Warning: Data either does not contain
(0)     a valid latitude coordinate array or doesn't contain one at all.
(0)     A valid latitude coordinate array should have a 'units'
(0)     attribute equal to one of the following values:
(0)         'degrees_north' 'degrees-north' 'degree_north' 'degrees north' 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg north'
(0)     check_for_lon_coord: Warning: Data either does not contain
(0)     a valid longitude coordinate array or doesn't contain one at all.
(0)     A valid longitude coordinate array should have a 'units'
(0)     attribute equal to one of the following values:
(0)         'degrees_east' 'degrees-east' 'degree_east' 'degrees east' 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
自己试了一下午 总是报经纬度单位的错 可是我查过明明经纬度都是有单位的