[gradsusr] How to determine Strength of Ocean Current using Grads

[Anil Kumar]

Hi Grad Users,

 

Below is my question and work done so far on my problem, please guide me to
solve.

 

Question : How to calculate the strength of ocean current data to provide
different colors to different levels using Grads ?

 

Work Done so far : Ocean current data downloaded from NOAA and below is the
ctlinfo from the NetCDF data

 

dset D:\OceanData\2014\05\25\rtofs_glo_2ds_f024_daily_prog.nc

title 2D Sfc Daily Prognostic 00Z21may2014: Forecast, downloaded May 25
15:22 UTC

undef 1.26765e+30

dtype netcdf

xdef 720 linear 74.16 0.49998

ydef 360 linear -90 0.49998

zdef 1 linear 1 1

tdef 1 linear 00Z25MAY2014 1mn

vars 2

u_velocity=>u_velocity  1  t,z,y,x  eastward_sea_water_velocity (m/s)

v_velocity=>v_velocity  1  t,z,y,x  northward_sea_water_velocity (m/s)

endvars

 

Am using below selected commands to generate vectors, and automatically it
gives in strength in terms of length of arrow.

 

sdfopen D:/ OceanData /2014/05/25/rtofs_glo_2ds_f024_daily_prog.nc

d u_velocity.1; v_velocity.1

 

if I make vector's scaling fixed to 0.015 using 'set arrscl 0.15'. 

 

So how can I calculate strength of vectors to provide them colors according
to levels ?

 

Thanks & Regards

Anil Kumar

 

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