# [ncl-talk] Querry regarding wind shear area average plot

Dennis Shea shea at ucar.edu
Thu Dec 5 15:59:55 MST 2019

```I hesitate to answer this because I do not want to end up doing the
programming.
*You must do the work.*

To get you started:

u(nens,time,lev,lat,lon), v(nens,time,lev,lat,lon)

pHigh   = 250
pLow    = 850
ushear = u(:,:,{pHigh,:,:)-u(:,:,{pLow},:,:)
vshear = v(:,:,{pHigh},:,:)-v(:,:,{pLow},:,:)
ushear at long_name = "USHEAR: ("+pHigh+"-"+pLow+")"
vshear at long_name = "VSHEAR: ("+pHigh+"-"+pLow+")"
ushear at units           = u at units
vshear at units           = v at units
copy_VarCoords(u(:,:,0,:,:), ushear)
copy_VarCoords(v(:,:,0,:,:), vshear)

printVarSummary(ushear)                          ; (nens,time,lat,lon)
printVarSummary(vshear)

shear = sqrt(ushear^2 + vshear^2)
shear at long_name = "SHEAR"
shear at units     = ushear at units
copy_varCoords(ushear, shear)
printVarSummary(shear)

----
Perhaps:

[1] clat(nens,ntim) and clon(nens,ntim)  ; storm center for each ensemble
member at each time.
[2] Use *gc_latlon*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/gc_latlon.shtml> to
calculate the distance from the storm center(s)
[3] Calculate areal means according to distance.

----
Another example that might be useful:
*http://www.ncl.ucar.edu/Applications/regrid.shtml*
<http://www.ncl.ucar.edu/Applications/regrid.shtml>
See Example: regrid_15.ncl

<http://www.ncl.ucar.edu/Applications/Scripts/grid2geocircle.ncl>

On Fri, Nov 29, 2019 at 9:44 AM Goriparthi Pavani via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Hi,
> I want to plot magnitude of shear for each ensemble member by taking
> average of the difference in wind velocities between the 850 hPa and 250hPa
> levels at every grid point that is between 200 and 500km from the surface
> center for a tropical cyclone.
> Domain used is moving nest with 3km resolution.
>
> wind shear magnitude between 200 and 500km from surface center.
>
> Regards
> Pavani
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