[IDV #TYB-719779]: Support request

Hi Mohit-

> I used the formula, dirn(vecr(u,v)) for producing wind azimuth map. I'm not
> able to figure out whether the code "(dirn(vecr(u,v))" takes north or east
> into account for calculating the direction of wind. I would request you to
> give me some hints for solving this issue.

Yes it does.  dirn gives the direction relative to true north, dirr gives
the direction in grid relative coordinates.  See the documentation at:

http://www.unidata.ucar.edu/software/IDV/docs/userguide/tools/JythonLib.html

> Thanks for the guidance. Now, i am able to produce wind angle grid using U
> and V wind component but the value ranges from 0 to 255 degree. I will be
> thankful, if you could explain me about fixing up the exact wind angle
> values.


What display are you using to view these?  If you are using the image
display, then the default range for the color table is 0 to 255.  You
can change this by using the Change Range menu in the Color Table menu
of the display control.  Change it to 0 to 360.

Don Murray

> On Thu, Nov 20, 2008 at 1:20 AM, Mohit Kalra <address@hidden> wrote:
> 
> > Hi Don,
> >
> > Thanks for the guidance. Now, i am able to produce wind angle grid using U
> > and V wind component but the value ranges from 0 to 255 degree. I will be
> > thankful, if you could explain me about fixing up the exact wind angle
> > values.
> >
> > Thanks in advance.
> >
> > Mohit
> >
> >
> >
> >
> > address@hidden> wrote:
> >
> >> Hi Mohit-
> >>
> >> > I guess, produced wind vector flow is not in the form of grid. I tried
> >> to
> >> > use dirn(Vector) formula using driv jython method. In the formula editor
> >> > used dirn(Vector) for calling the formula. I had impression that the
> >> > formula will convert wind flow vector into wind azimuth (angle) grid.
> >> The
> >> > issue is need to assign wind flow vector as an input in the field
> >> selector
> >> > window. Unfortunetly, produced wind flow vector is not appearing into
> >> the
> >> > field selctor window. I would request you to test the attached data
> >> > (previous mail) for producing the wind azimuth angle grid. I would also
> >> > request you to kindly explain me the steps for the same.
> >>
> >> You can create the vector from the u and v using the vecr Jython procedure
> >> or by using the "Grid->Make flow vectors from grid relative u and v data"
> >> formula.
> >>
> >> You can use the Grid->Create Grid Diagnostic formula and in the
> >> dialog, use  dirn(vecr(u,v)).  You will then be prompted for the
> >> u and v variables and can select your u and v grids at that point.
> >> Or you could create a new formula to hold dirn(vecr(u,v)) so you can
> >> call it over and over.
> >>
> >> Don Murray
> >> > On Wed, Nov 19, 2008 at 8:10 PM, Mohit Kalra <address@hidden>
> >> wrote:
> >> >
> >> > > Dear Don,
> >> > >
> >> > > Thanks for your quick reply. Though, i'm using IDV but not familiar
> >> with
> >> > > all the functions. So, i would be thankful, if you could explain me
> >> steps
> >> > > for using dirn or dirv Jython methods in the griddiag.py. Further, i
> >> > > enclosed wind data in netCDF format for your consideration (U and V
> >> > > component at 850mb pressure level with geopotential height). I'm
> >> interested
> >> > > in producing the raster grid with the wind angle value from 0 to 360
> >> degree.
> >> > >
> >> > >
> >> > > Waiting for your reply.
> >> > >
> >> > > Thanks and regards,
> >> > >
> >> > > Mohit
> >> > >
> >> > >
> >> > >
> >> > >
> >> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > address@hidden> wrote:
> >> > >
> >> > >> Hi Mohit-
> >> > >>
> >> > >> This is Don.
> >> > >>
> >> > >> > Thanks for your reply. I have another question regarding wind
> >> vector
> >> > >> flow
> >> > >> > estimation using IDV. I have calculated wind speed and flow vector
> >> using
> >> > >> U,
> >> > >> > V and W component of wind. I am wondering if the flow vector could
> >> be
> >> > >> use
> >> > >> > for getting the wind azimuth angle from 0 to 360 degree.
> >> > >> >
> >> > >> > Looking forward to hear from you.
> >> > >> >
> >> > >> > Thanks and regards,
> >> > >>
> >> > >> You can calculate the direction using the dirn or dirv Jython
> >> > >> methods in the griddiag.py.  dirn will return the true north
> >> > >> direction, dirv will return the grid relative direction (if
> >> > >> you have a grid relative vector).  You would call this with
> >> > >>
> >> > >> dirn(vector)
> >> > >>
> >> > >> where vector is the flow vector grid.
> >> > >>
> >> > >> Don Murray
> >> > >>
> >> > >> Ticket Details
> >> > >> ===================
> >> > >> Ticket ID: TYB-719779
> >> > >> Department: Support IDV
> >> > >> Priority: High
> >> > >> Status: Open
> >> > >>
> >> > >>
> >> > >
> >> >
> >> >
> >>
> >>
> >> Ticket Details
> >> ===================
> >> Ticket ID: TYB-719779
> >> Department: Support IDV
> >> Priority: High
> >> Status: Open
> >>
> >>
> >
> 
> 


Ticket Details
===================
Ticket ID: TYB-719779
Department: Support IDV
Priority: High
Status: Open