[ncl-talk] := or =

[Ehsan Taghizadeh]

Hi,I faced something interesting which I didn’t know in NCL. It might be obvious for many of you, however, I would like to share it.I tried to plot wind barb at 10m level above the ground from GFS0.25 data. First, I used following lines: u10 = fi->UGRD_P0_L103_GLL0({10},:,:) v10 = fi->VGRD_P0_L103_GLL0({10},:,:) u10 := u10*1.94386 ; Turn wind into knots v10 := v10*1.94386 u10 at units = "kts" v10 at units = "kts"The resulted map was something like plt1 which is wrong.Then I tried to use the following lines: u10 = u10*1.94386 ; Turn wind into knots v10 = v10*1.94386This turn the resulted map (plt2) was correct.I’ll be thankful if some one could explain me why using “:=” is false and using “=” is true in this situation.


-----------------------------------------------------------------------------Sincerely,Ehsan Taghizadeh

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