Mapping RCP Lambert Conformal

[brandi_clark@mavs_uta_edu]

I have been going back and forth with CISL help, and they directed me to this site.<br /><br />I am trying to map data from the CESM RCP 8.5 simulations. I couldn't find out whether or not the
data are on a native grid for Lambert Conformal, so I am assuming not. To get NCL to read in the
lat and lon correctly, I found the code on NCL's website:

; open file and read in data
;*******************************************
  f    = addfile ("pre.8912.mon.nc", "r")
  P    = f->pre
  LAT2D= f->lat
  LON2D= f->lon
;********************************************
;reorder arrays
;********************************************
  p = P(time|:,ycoord|:,xcoord|:)
  lon2d=LON2D(ycoord|:,xcoord|:)
  lat2d=LAT2D(ycoord|:,xcoord|:)
;********************************************

I am not sure what to use for ycoord and xcoord. I printed the variables and included screen shots
of lat and lon.

I received this rersponse:

Hi Brandi,

From your screenshots, it looks like you have a rectilinear grid, which is relatively easy to plot.
A rectilinear grid is one that can be represented by one-dimensional coordinate arrays.

I agree with you that your data is probably not on a native lambert conformal map.

If you want to put it on a Lambert Conformal, you will need to set  the two corners of your grid,
and set the two parallels and meridian.

See the sample script, which allows you to set LAMBERT_CONFORMAL to False if you want the default
cylindrical equidistant map.

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"  
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"  
begin
  f    = addfile ("myfile.nc", "r")
  x    = f->x

  wks  = gsn_open_wks ("ps", "lcnative")          ; open workstation
  
  res                   = True               ; plot mods desired
  res@cnFillOn          = True               ; color fill  
  res@gsnAddCyclic      = False              ; if regional data

  LAMBERT_CONFORMAL = True      ; Use a lambert conformal map

  if(LAMBERT_CONFORMAL) then
    res@mpProjection      = "LambertConformal"
    res@mpLimitMode       = "Corners"            ; choose range of map
    res@mpLeftCornerLatF  = min(x&lat)    ; change as necessary
    res@mpLeftCornerLonF  = min(x&lon)    ; change as necessary
    res@mpRightCornerLatF = max(x&lat)    ; change as necessary
    res@mpRightCornerLonF = max(x&lon)    ; change as necessary
    
    res@mpLambertParallel1F = 30.    ; change as necessary
    res@mpLambertParallel2F = 55.    ; change as necessary
    res@mpLambertMeridianF  = 45.    ; change as necessary
  else
    res@mpMinLatF = min(x&lat)    ; change as necessary
    res@mpMinLonF = min(x&lon)    ; change as necessary
    res@mpMaxLatF = max(x&lat)    ; change as necessary
    res@mpMaxLonF = max(x&lon)    ; change as necessary
  end if  

  plot = gsn_csm_contour_map(wks,x,res)
  
end

I am still having issues:I am a little confused between the example script that NCL gives and the script that you gave me.  This is my code: load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl" begin   fname = addfile ("b40.rcp8_5.1deg.007.cam2.h0.2020-07.nc", "r") ; read in file from path   t = fname ->T   tlat1 = 60.0  tlat2 = 30.0  clon  = -98.5   wks = gsn_open_wks("ps","RCP8.5_T_2020_test")   res  = True  res@cnFillOn                    = True ; fills in contours  res@cnLinesOn                   = False ; don't draw contour lines  res@cnLineLabelsOn              = False ; don't label contours   res@mpProjection                = "LambertConformal"  res@mpLambertParallel1F         = tlat1  res@mpLambertParallel2F         = tlat2  res@mpLambertMeridianF          = clon     res@mpLimitMode                 = "Corners"  res@mpLeftCornerLatF            = min(T&lon)  res@mpLeftCornerLonF            = min(T&lon)  res@mpRightCornerLatF           = max(T&lat)  res@mpRightCornerLonF           = max(T&lat)    tfDoNDCOverlay = True ; Draw the map    map = gsn_csm_contour_map(wks,T,res)  end  I'm not sure what NCL is wanting for the red area. In order for me to use lat and lon as variables, I thought they had to be read in as per the example script here: https://www.ncl.ucar.edu/Applications/Scripts/lcnative_1.ncl
In that example, it looks like they are reading in the one-dimensional lat and lon variables and converting them to 2-dimensional variables lat2d and lon2d, which are then used to define the corners.

 

[hannay]

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