[ncl-talk] Visualization of SAF NWC products

[Athanasios Karagiannidis]

Dear sirs/madams

I want to visualize SAF NWC output data using ncl. They are included in an h5 file.
These data are not in a simple lat-lon grid.
After an earlier contact with you i managed to visualize them by creating such a grid, but i feel that the image is not accurate.
What i want to help me with, is to tell me weather there is a standard way or an already existing script to visualize correctly that kind of data.
To help you I provide the following:

1. A sample datafile.
2. The printVarSummary output
3. A screenshot of the HDFView visualization of the variable where the Variable info are shown (more or less the same info with printVarSummary).
4. The script i used (although, i do not think that you need that!). The lat/lon limits that i have n my script are not acurate. I used them to make the visualization.


---------- printVarSummary------------------------------

ncl 2> printVarSummary(CT)

Variable: CT
Type: ubyte
Total Size: 370688 bytes
            370688 values
Number of Dimensions: 2
Dimensions and sizes:    [DIM_000 | 512] x [DIM_001 | 724]
Coordinates: 
Number Of Attributes: 11
  CLASS :    IMAGE_INDEXED
  ID :    CTTH_HEIGHTED
  IMAGE_COLORMODEL :    RGBH_HEIGHTED
  IMAGE_SUBCLASS :    IMAGE_INDEXED
  IMAGE_VERSION :    1.0GE_INDEXED
  N_COLS :    724
  N_LINES :    512
  OFFSET :    -2000
  PALETTE :    ��8�3
  PRODUCT :    CTTHE_INDEXED
  SCALING_FACTOR :    200

---------------------------------------------------------------------------------

---------------- My Script ---------------------------------------------------

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
cdf_file = addfile("SAFNWC_MSG2_CTTH_200812121100_Greece______.h5","r")
CT = cdf_file->CTTH_HEIGHT(:,:)

  res                             = True

   lat    = fspan(50,20,512) ; A.K. -- reverse the matrix
   lon    = fspan(10,30,724)
   CT!0   = "lat"                   ;-- set name of CT dimension 0
   CT!1   = "lon"                   ;-- set name of CT dimension 1
   CT&lat =  lat                    ;-- assign lat array to CT
   CT&lon =  lon                    ;-- assign lon array to CT
   CT&lat at units = "degrees_north"  ;-- set the units of the named coordinate lat
   CT&lon at units = "degrees_east"   ;-- set the units of the named coordinate lon

res at gsnAddCyclic = False
res at tiMainString         = "Default Color"    ; main title
res at cnFillOn             = True               ; turn on color fill
 res at mpMaxLatF                   = 50           ; choose subregion           
 res at mpMinLatF                   = 20
 res at mpMaxLonF                   = 30
 res at mpMinLonF                   = 10

xwks = gsn_open_wks("pdf","CloudTops")
plot = gsn_csm_contour_map(xwks,CT,res)
end

--------------------------------------------------------------------------------

Thank you in advance.


Sakis




Athanasios F. Karagiannidis
Physicist, PhD Meteorology and Climatology
E-mail: thankar at live.com 		 	   		  
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