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

From: brianjs _at_nyahnyahspammersnyahnyah <_at_nyahnyahspammersnyahnyah>
Date: Tue May 07 2013 - 10:29:55 MDT

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

ncl-talk mailing list
List instructions, subscriber options, unsubscribe:

Received on Tue May 7 10:30:17 2013

This archive was generated by hypermail 2.1.8 : Wed May 15 2013 - 10:19:28 MDT