[ncl-talk] Wind Bias calculation

[Dr. Suman Maity]

Dear all
I want to calculate and plot wind bias (both magnitude and direction). I
did the following:
begin
;--------------------------------
; Data dir and files
; Opening data file
;--------------------------------
  ddir = "/media/Segate4TB/data_wind/"
  obsufile = "uwnd.850.1982-2016.JJASmean.nc"
  obsvfile = "vwnd.850.1982-2016.JJASmean.nc"
  modelfile = "model.850.1982-2016.JJASmean.remap.nc"
  obsudata = addfile(ddir+obsufile,"r")
  obsvdata = addfile(ddir+obsvfile,"r")
  modeldata = addfile(ddir+modelfile,"r")
;--------------------------------
; Reading variables
;--------------------------------
  uo = (rm_single_dims(short2flt(obsudata->u)))
  vo = (rm_single_dims(short2flt(obsvdata->v)))
  um = rm_single_dims(modeldata->ua)
  vm = rm_single_dims(modeldata->va)
;--------------------------------
; preparing data for plotting
;--------------------------------
  windo = sqrt(uo^2+vo^2) ; magnitude of renalysis wind
  copy_VarCoords(uo,windo)
  windm = sqrt(um^2+vm^2) ; ; magnitude of model wind
  copy_VarCoords(um,windm)
  magb = windm - windo
  copy_VarCoords(windo,magb)
  ub = um - uo
  vb = vm - vo
 plot = gsn_csm_contour_map_ce(wks,magb,res)
 uv_plot  = gsn_csm_vector(wks,ub,vb,vcres)
 overlay(plot,uv_plot)
Where "res" is the contour plot rresources and "vcres" is vector resources.
Now I have the following questions:

1) Is the code is correct for wind bias plot?
2) What will be the direction of the bias wind? I mean if bias wind is
flowing from the east will it be called easterly as we are doing in general
wind? I get confused with the result of some published journals.
3) If let's suppose bias wind is easterly, then what can be commented about
model as well as reanalysis wind?
Please reply. Any sort of suggestion will be of great help.
Thanking you,

Best
Suman
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