Re: Plotting Correct Wind Direction in Lamont, OK Profiler Data using NCL.

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Tue May 07 2013 - 12:12:11 MDT

Hi Brian,
I suspect you just need to set the boolean resource vcMapDirection to False. The default setting, True, is appropriate for maps, but not in situations such as vertical profiles where the X and Y axes have very different units for there coordinates. We could probably make NCL smart enough to recognize the difference and adjust automatically but it has not happened yet. Here is a summary of the doc for vcMapDirection:

This resource controls whether the vector direction is mapped into the same coordinate space as the
vector location, or whether it is rendered in a locally uniform cartesian coordinate space.


On May 7, 2013, at 10:29 AM, "brianjs" <> wrote:

> Good Morning,
> Most recently, I have attempted to plot Lamont, OK Profiler wind data from the ARM site available to the public using NCL. For the most part, the plotting seems correct, with the exception that the wind directions seem to be offset by approximately 45 degrees or so. I have attached a copy of a Lamont profiler dataset (attachment 1) along with a copy of my code (attachment 2) and an example of the Lamont data plotted in both my code (attachment 3) and in IDL (that is displayed publicly on the ARM site) to illustrate this difference (attachment 4). Please note that I am plotting the low power setting, so when looking at the ARM plotted example in IDL, please only refer to the bottom image of the document.
> I have already taken steps to filter out bad data and I have commented the code in great detail in attempt to explain exactly what it is I am doing. I also left all the print and print var summaries in for those who want to look at those individual components.
> To correctly plot the data, I reassigned the time and height arrays to the winds instead of them being functions of range-gate, power and the offset time (which is only in seconds).
> Essentially, I am attempting to compare this data with WRF simulated vertical profiles and I attached both the code, with an example image as well (attachments 5 and 6, respectively) for anyone's curiosity and to show why the Lamont data is plotted this way. For the record, the WRF is a 36 hour forecast that is 3-hourly vs. Lamont data which is plotted hourly at only the 24 hour day. In the future, I will concatenate profiler data daily sets and reduce them from hourly to 3-hourly to properly account for this.
> My problem/question is how to address the wind direction problem? The data does have a wind speed and direction variable, but NCL must use the u and v components to generate a vector (and subsequently the wind barbs). I am not understanding though why the u and v components alone are not generating what the IDL illustrations show. These components alone should account for proper direction, and the wind speeds seem to be correct as well.
> Again, I appreciate any input that can be provided!
> Brian Squitieri
> Graduate Research Assistant
> Iowa State University
> <sgp915rwpwindconC1.a1.20120502.000022.cdf><data_profiler_plot.ncl><><sgp915rwpwindconC1.a1.20120502.000022.png><WRF_wind_profile.ncl><>_______________________________________________
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Received on Tue May 7 12:12:21 2013

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