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Plotting subset netCDF with grads

Download subset netCDF from DataEx

  • In DataeEx visit Forecast > Subset netCDF.
  • Select forecast source, parameter and region values and proceed to download netCDF as shown in the image below:

Download subset netCDF

Plotting with GRADS

  • Install Grads in windows or Linux. Manual | Download

  • Ensure you have the following files in the folder where you are running the scripts:

    • netCDF file containing forecast data downloaded from DataEx.
    • Grads scripts (sample script provided for rainfall to customize as required for other parameters)
    • Color bar file (cbar.gs) - also provided to download
    • Shape file for overlay (for district or other layers)
    • Sample file. (Copy the script and put in a file Plotgrads_pcp.gs or any preferred name). Or you can use your own script files.
  • A sample code is shown in below. (Copy the code and put in a file Plotgrads_pcp.gs or any preferred name).
  • To plot run command (use pbc or pbc depending on the mode of plotting (p=portrait or l=landscape)
       grads -pbc Plotgrads_pcp.gs

You should see plots like the following:-

Grad plots

Example Grads Script for plotting rainfall

****************************************************************
** This script plots downloaded subset of ECMWF HRES data 
** RIMES **
****************************************************************

reinit

**Provide the NC file downloaded from the DataEx.

'sdfopen ECMWF_HRES_NC_28.78N_25.85S_92.74E_88.2W.nc'


**** DATA loop for plotting for daily accumulated****

i=1

k=1

day=24

while (i<41)

j=i+4

** SET the color bar and map

'set clopts 1 2 .10'

'set clevs 0.1 1 5 10 15 20 25 30 50 75 100 125 150 175'

'set ccols 0 5 13 3 10 7 12 8 2 6 9 14 4'

'set grads off'

*'set mpdraw off'

'set gxout shaded'

'set mpdset hires'

***Plotting parameter.. for total precipitation (CP and LSP)

if(i=1)

'd ((cp(t='j')-cp(t=2))+(lsp(t='j')-lsp(t=2)))*1000'


*************

**Put the Shape file that you want to overlay here...

**Only put the file name and no extension like .shp.

**Ensure the location of the file is correct

*************

*'set line 4 1 2'

*'draw shp bhu_adm1'

*******************

else

'd ((cp(t='j')-cp(t='i'))+(lsp(t='j')-lsp(t='i')))*1000'

*******************


*'set line 4 1 2'

*'draw shp bhu_adm1'

*******************


endif

*******************

*Plot cbar and add titles

*******************

'run cbar 1.1 0 4.3 2.0'

'set font 2'

'set strsiz .14'

'draw string 1.5 10.5 NHMS/INIT:ECM_00UTC'

'set font 1'

'draw string 4.4 8.99 Daily (24 Hrs) Accumulated Precipitation
Forecast'

'draw string 4.5 8.69 Valid at: 20210702 + 'day' Hr (UTC)'

'set string 2 9 2 1'

'set strsiz .15'

'draw string 4.2 8.35 ********** DAY 'k' **********'

'draw string 4.2 2.55 (mm)'

'set font 2'

'set strsiz .10'

'draw string 2.2 1.75 Forecast initialized with 20210702 00 UTC
data'

day=day+24

'gxprint rain'k'.png png white'

'clear'

k=k+1

i=i+4

endwhile

quit