[wxqc] quick question
Gerry Creager N5JXS
gerry.creager at tamu.edu
Wed Apr 19 08:28:32 EDT 2006
OK, so this is a little off topic, but I'm trying to get a lot of things
done quickly and this group tends to have some good expertise...
I'm instrumenting a site for some liquified natural gas dispersion
experiments, and we are gonna do it tomorrow. I'm putting up a pair of
Vaisala WXT-510s, one at 2 meters, one at 10 meters, in as close to an
unobstructed area as I can get near the test site ("prop") as possible
while staying out of the anticipated plume (if the plume ignites, and
the WXT-510s are in it, they'll become molten pieces of thermoplastic
slag...).
OK, the question: Does anyone have a good idea of the Nyquist frequency
for wind measurements? I've got a request for 1-sec measurements to
capture all the dynamics. I can do this but suspect the noise will
overcome the data and I'll end up having to decimate the data to get a
reasonable value. I guess I can look at an FFT in the frequency domain
and see if anything drops out on the floor, but that's introducing a lot
of work.
I seem to recall from the depths of my brain, that wind data should be
collected at a rate not greater than once per 30 sec (twice/min), but
now I can't find documentation on that.
Adding insult to injury, the folks I'm working with on this don't know
what sort of continuous data will really aid their analysis. They do
know they need to initialize the FEM3A codes they're running with
surface met data (temp, pressure, humidity, anemometry) but there's more
than a little confusion as to whether it takes continuous data while
it's running or if it's an isolated measurement.
I'll be looking at data for weeks after this, so there's no real time
constraint on answers, if someone's got something!
Thanks, Gerry
Texas Mesonet
AP009
--
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
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