Re: How to Extract and plot wind vectors in a box

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Mon Apr 09 2012 - 09:06:33 MDT

[1] Sending a 18MB attachment is not allowed. That clogs up all people
     who subscribe to ncl-talk. If your site does not allow ftp, please
     find a suitable replacement on your end. eg via the WWW

     Fortunately for you , the administrator made and exception
     this time.

[2] The reason why the plot "the vectors are not as expected" is that
     you did not tell the graphics routines the geographic coordinates
     of the data to be plotted.

Attached is a slightly modified script.

On 4/8/12 11:58 PM, Ragi A.R wrote:
> Sir,
> ftp has been blocked here for security purpose. The file size is 18.7MB
> so am attaching it here. The met_em file is WRF input file after
> Pre-processing (after WPS run).
>
> The NCL Version am using is:6.0.0
> The type of system: x86_64 GNU/Linux
> /-- /
> ///Regards,/
> /A.R.Ragi/
> /Research Scholar
> /
> /Centre for Atmospheric Sciences
> IIT Delhi, Hauz Khas
> New Delhi, India.
> /
> //
>
>
>
>
> On Sun, Apr 8, 2012 at 20:29, Dennis Shea <shea@ucar.edu
> <mailto:shea@ucar.edu>> wrote:
>
> Before proceeding: you did not answer the question that was asked.
>
> Is the file you are reading generated by the WRF model?
>
> If so, Please ftp the file to
>
> ftp ftp.cgd.ucar.edu <http://ftp.cgd.ucar.edu>
> anonymous
> <use your email address for the password>
> cd incoming
> put met_em.d01.2009-04-01_00:00:00__.nc <http://00.nc>
> quit
>
> Send email to ncl-talk (you must subscribe first) with the following
> information:
>
> Send an email after you have successfully completed the transfer.
>
> The version of NCL you are running (ncl -V).
> The type of system you are on (uname -a).
>
>
> On 4/8/12 1:22 AM, Ragi A.R wrote:
>
> Sir,
>
> I tried removing that line but still am getting the same plot /.
>
>
> -- /
> ///Regards,/
> /A.R.Ragi/
> /Research Scholar
> /
> /Centre for Atmospheric Sciences
> IIT Delhi, Hauz Khas
> New Delhi, India.
> /
> //
>
>
>
>
> On Sat, Apr 7, 2012 at 19:11, Dennis Shea <shea@ucar.edu
> <mailto:shea@ucar.edu>
> <mailto:shea@ucar.edu <mailto:shea@ucar.edu>>> wrote:
>
> You have used a graphical option (resource)
>
>
> res@vcMinDistanceF = 0.025 ; thin out vectors
>
> that does exactly what the the comment states ...
> it 'thins' the vectors.
>
> Comment or eliminate that line
>
> ;res@vcMinDistanceF = 0.025
>
>
> On 4/7/12 2:01 AM, Ragi A.R wrote:
>
>
>
>
>
> Dear NCL users,
>
> I have a*.nc* file (*met_em_files* after WPS) which have U
> (wind) and V
>
> (Wind) values for the domain 7N-20N; 70E-80E and which is
> staggered. I
> want to extract and unstagger them (only u and v) and
> then plot
> (u,v)
> vector for the domain */8N; 76E-77E/* and *18N; 73E-74E*
> (domain
> attached /doc1.pdf/).
>
>
> The below is my approach (I modified the domain from
> 73E-77E and
> 78N-18N).
>
> But the issues are:
> 1). The vectors are not as expected. I have values at
> all grid
> points
> but only few vectors r there.
> 2). Not able to generate the box I wanted (as
> highlighted in
> doc1.pdf).
> 3). I wanted to plot the (u,v) vector at the four
> corners of the
> box.
>
> Can anyone suggest a solution to 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/wrf/WRFUserARW.ncl"
> load
> "$NCARG_ROOT/lib/ncarg/____nclscripts/wrf/WRF_____contributed.ncl"
>
> begin
>
> a =
> addfile("met_em.d01.2009-04-____01_00:00:00.nc <http://00.nc>
> <http://00.nc> <http://00.nc>","r")
>
>
>
>
> uu = wrf_user_getvar(a, "UU", 0)
> ua = uu(1,:,:)
> u = wrf_user_unstagger(ua,ua@____stagger)
>
>
> vv = wrf_user_getvar(a, "VV", 0)
> va = vv(1,:,:)
> v = wrf_user_unstagger(va,va@____stagger)
>
>
>
> wks = gsn_open_wks("ps", "uv_plot") ; open ps file
> gsn_define_colormap(wks,"gui_____default") ;
> choose
>
> colormap
>
> res = True ;
> plot mods
> desired
> res@gsnMaximize = True ;
> maximize
> size
> res@gsnSpreadColors = True ;
> use full
> colormap
> res@gsnSpreadColorEnd = -2
> res@lbOrientation = "vertical" ;
> vertical
> label bar
> res@mpFillOn = True ; no
> map fill
> res@vcRefMagnitudeF = 5 ; make
> vectors
> larger
> res@vcRefLengthF = 0.025 ;
> ref vec
> length
> res@vcMinDistanceF = 0.025 ;
> thin out
> vectors
> res@vcGlyphStyle = "CurlyVector" ;
> choose
> wind barbs
> res@vcLabelsOn = True
> res@vcMonoLineArrowColor = False ; color
> barbs by scalar
>
> minlat = 8
> maxlat = 18
> minlon = 73
> maxlon = 77
>
> res@mpMinLatF = minlat
> res@mpMaxLatF = maxlat
> res@mpMinLonF = minlon
> res@mpMaxLonF = maxlon
> res@mpOutlineBoundarySets = "National"
> res@pmTickMarkDisplayMode = "Always"
> res@mpFillOn = False ; turn
> off map fill
> res@mpOutlineDrawOrder = "PostDraw"
>
> plot=gsn_csm_vector_map_ce(____wks,u,v,res)
>
>
>
> end
>
>
> /-- /
> ///Regards,/
> /A.R.Ragi/
> /Research Scholar
> /
> /Centre for Atmospheric Sciences
>
> IIT Delhi, Hauz Khas
> New Delhi, India.
> /
> //
>
>
>
>
>
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Received on Mon Apr 9 09:06:51 2012

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