<div dir="ltr"><div>The wind barbs are 'independent' of the units. If m/s are the input units, then the 'half-barb' is at 5 m/s, full barb is a 10 m/s, etc . If knots, 'half-barb' is at 5 knots, full barb is a 10 knots.<br><br></div>I am not aware of any international standard for 'wind barbs'.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Oct 18, 2014 at 1:44 AM, 李嘉鹏 <span dir="ltr"><<a href="mailto:lijpbasin@126.com" target="_blank">lijpbasin@126.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial">Hi,
I am trying to figure out the wind speed unit used by the `skewT_PlotData` function,
[the documentation page]
(<a href="http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml" target="_blank">http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml</a>)
and the [skewT example page]
(<a href="http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml" target="_blank">http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml</a>)
says the unit of the wind speed is either knot or m/s, but they are not the same:
$ udunits2
udunits2: Using default XML database
You have: knot
You want: m/s
1 knot = 0.514444 m/s
x/(m/s) = 0.514444*(x/knot)
If I pass float values to the `WSPD` (`u`) and `WDIR` (`v`) argument, how do I know or
control the way `skewT_PlotData` interpret these values?
[The WMAP documentation on wind barbs]
(<a href="http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-140" target="_blank">http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-140</a>)
indicates that the unit is knot, and [The WMAP documentation on station data]
(<a href="http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-151" target="_blank">http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-151</a>)
mentioned a property called `UNT`, but it's not available for the `WMBARB` function.
I tried to get these information from the source code `ni/src/examples/gsun/skewt_func.ncl`,
the function `skewT_PlotData_Original` or `skewT_PlotData_Panel` does not perform unit
conversion, and the properties set for the `WMBARB` function (WDF, COL, WBA) are not related
to wind speed units.
I'll be grateful if someone can provide the exact information.
---
Regards</div><br><br><span title="neteasefooter"><span></span></span><br>_______________________________________________<br>
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