On Saturday 05 February 2011 05:38, Ansley Manke wrote:
> Hi-
> I don't know why the locations would be wrong. I wonder if it could be
> be the order of operations, y=@loc:`minval`, and the averaging in Z?
> SET MODE DIAGNOSTIC might help sort that out. You could try defining a
> variable first,
>
> let uwndave = uwnd[z=`zl`:`zu`@ave]
>
> and operate on that to see what difference it makes.
>
> The reason that /LINE has no effect is that each PLOT command is drawing
> a separate single-point line, and has no knowledge of the points that
> came before. You could save each location after it's computed, and plot
> at each X a 2-point line using {xpos,xlast}, {ypos,ylast}.
>
> Ansley
>
> On 2/4/2011 3:23 AM, Samrat Rao wrote:
> >
> > Hi,
> >
> > I am trying to locate and plot the minimum U wind values on a lat-lon
> > figure. I am attaching the figure generated.
> >
> > After ploting the U wind contours i use the following:
> >
> > repeat/range=0:120:2/name=xpos ( \
> > let minval = uwnd[x=`xpos`e,y=@min,z=`zl`:`zu`@ave,l=7]; \
> > let ypos = uwnd[x=`xpos`e,y=@loc:`minval`,z=`zl`:`zu`@ave,l=7]; \
> > list ypos; \
> >
> > plot/line=14/color=red/thickness=3/size=0.15/symbol=3/vs/nolabel/overlay
> > xpos,ypos )
> >
> > As you can see the symbols are being plotted below the location of
> > minimum U wind. I have the following questions:
> >
> > 1) The reason for the incorrect location of the symbols. I am not
> > having this problem with NCEP reanalysis data.
> >
> > 2) I am unable to get the 'line' qualifier connect the different
> > symbols. How to do this?
> >
> > 3) At some locations there is a discontinuity (for example around
> > 55E). To me it looks artificial.
> >
> > 4) In case there is a missing value for 'ypos', then how do i ensure
> > that this does not cause an error and abort in the script execution?
> >
> > I hope you people will have patience to reduce some of my difficulties.
> >
> > Thanks,
> > Samrat Rao.
>