Creates a vector plot from ARW WRF model output.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" ; These two libraries are automatically load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl" ; loaded from NCL V6.4.0 onward. ; No need for user to explicitly load. function wrf_vector ( nc_file : file, wks : graphic, data_u [*][*] : numeric, data_v [*][*] : numeric, res : logical ) return_val  : graphic
Reference to an input netCDF file opened with addfile.wks
A two-dimensional array of the U component of the wind.data_v
A two-dimensional array of the V component of the wind.res
A variable containing an optional list of plot resources, attached as attributes.
A scalar id of the plot created is returned.
This function creates a vector plot (but does not draw it). To draw the plot, see the example below.
If data has a _FillValue attribute, this value will be used as a missing value.
If data_u has a "description" attribute, this value will be used in the plot title. (See description of "FieldTitle" attribute below.)
This function recognizes some special resources that can be attached as attributes to res:
- NumVectors - this defaults to 25. If this resource is set
along with vpWidthF, then these two
values will be used to determine values
for vcMinDistanceF and
(opts@vpWidthF/opts@NumVectors). Otherwise, these two resources will
default to 0.02.
- FieldTitle - This becomes the main title of the vector
plot. If not set, then the "description" attribute of the data_u
variable will be used, if available.
- SubFieldTitle - if set, this will be appended to the
FieldTitle title with a space between the two.
- UnitLabel - if set, this will be appended to the existing
FieldTitle title in parentheses. If not set, the "units" attribute of
the data_u variable will be used, if available.
- PlotLevelID - if set, this will be appended to the existing
FieldTitle title with an " at " between the two. If not set, the
"PlotLevelID" attribute of the data_u variable will be used, if
- NoHeaderFooter - Turn off all the extra titles. This
is useful if you need to panel the plot later.
The final main title could look something like "FieldTitle SubFieldTitle (UnitLabel) at PlotLevelID".
Other vector resources are internally set by this routine:
- vcGlyphStyle - "WindBarb"
- vcWindBarbColor - "black"
- vcRefAnnoOn - False (default is normally True)
- vcMinFracLengthF - 2.0
wrf_vector is part of a library of functions and procedures in WRFUserARW.ncl written to help users plot ARW WRF model data.
WRF-related questions should be sent to email@example.com.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl" a = addfile("wrfout_d01_2000-01-24_12:00:00.nc","r") wks = gsn_open_wks("x11","test") u10 = wrf_user_getvar(a,"U10",0) ; U component of the wind at 10m v10 = wrf_user_getvar(a,"V10",0) ; V component of the wind at 10m res = True res@gsnDraw = True ; Forces the plot to be drawn res@gsnFrame = True ; Frame advance vector = wrf_vector(a,wks,u10,v10,res)You can see some other example scripts and their resultant images at: