about gsn_csm_pres_hgt_vector

Deal all:

I have a question about gsn_csm_pres_hgt_vector function.

I plot the V wind and OMEGA in the lat_level plane. Here, the omega is magnified -100 times (as FIG.1). The script as this :

;************************************************
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"

begin
 
    f2 = addfile("/disk3/data/NCEP-2.5/monthly/pressure/vwnd.mon.mean.nc","r")
    f3 = addfile("/disk3/data/NCEP-2.5/monthly/pressure/omega.mon.mean.nc","r")
  
 vwnd1 = short2flt(f2->vwnd(7,0:11,{0:90},{95:110}))
 vwnd11 = dim_avg_n_Wrap(vwnd1,2)
; printVarSummary(vwnd11)
         omega1 = short2flt(f3->omega(7,0:11,{0:90},{95:110})) ;{45:20}
 omega11 = dim_avg_n_Wrap(omega1,2)
 w = -omega11*100.
; printVarSummary(omega11)
  
   wks = gsn_open_wks("eps","fig1")
 
   res = True
   res@cnLinesOn = False
   res@cnLineLabelsOn = False
   res@cnInfoLabelOn = False
   res@tmXTOn = False ; and right tickmarks.
   res@tmYROn = False
   res@vcRefMagnitudeF = 5.
   res@vcRefAnnoString1On = True
   res@vcRefAnnoString1 = "5m/s"
   res@vcRefAnnoOrthogonalPosF = -1
   res@vcRefAnnoString2On = False
   res@vcRefLengthF = 0.015
   res@vcGlyphStyle = "LineArrow"
   res@vcMinDistanceF = 0.008

   res@vpWidthF = 0.75
   res@vpHeightF = 0.6
   res@tiMainString = "1960-1978 MAM to JJA(1) meridional circulation"
   res@tiMainFontHeightF = 0.02
   res@gsnLeftString = ""
   res@gsnRightString = ""
   res@tiYAxisString = "p/hPa"
   res@tmYRMode = "Automatic"
   res@tmXBMode = "Explicit"
 
   plot = gsn_csm_pres_hgt_vector(wks,vwnd11,vwnd11,w,res)
   
end
    
However, I get the difference result by used GRADS.The omega is magnified 100 times (as FIG.2).

We can see the vertical speed much smaller than horizontal velocity in the fig1, Specifically in the 60N-90N, there are scarcely upward and downward.

In FIG2, in the 60-90N, there are downward clearly, and the omega is almost the same with the V-wind.

If I plot the FIG as the omega is magnified -1000 times (as FIG.3), the picture is very similar as FIG2.

My question is :
1) fig 1 and fig 2 is different by use the same data, why? which one is correct?
2) Did I need to magnified -1000 times in the vertical speed, when I use the gsn_csm_pres_hgt_vector function?

Thanks.

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