Number range CHAPTER Dec. 31, 2001

Information file for the National Oceanic and Atmospheric
Administration/Environmental Technology Laboratory's TEACO2 Doppler
Lidar wind profiles

TexAQS 2000

Text files are found at
[[www.etl.noaa.gov/\~ldarby/houston_profiles/text_files]{.underline}](http://www.etl.noaa.gov/).

PostScript files containing wind barb profile plots are found at
[[www.etl.noaa.gov/\~ldarby/houston_profiles/graphics_files]{.underline}](http://www.etl.noaa.gov/).
At this time, this directory contains profiles from 1E to 2E
constant-elevation scans for each day. Profiles from 20E to 30E scans
are available for some days.

\*\*\* Important note: Data in the text files are in UTC. Times were
converted to LST (UTC - 6) for the profile plots. \*\*\*

Please refer to Houston_vad_record for a listing of times of the first
and last wind profiles available for each day.

1\. File name conventions:

File name convention for text files

MMMDD.txt

MMM is the month

DD is the day

File name convention for graphics files:

MMMDD_N_Xdeg.txt

MMM is the month

DD is the day

N is the minimum elevation angle of the scans the profiles were derived
from.

X is the maximum elevation angle of the scans the profiles were derived
from.

Some files have 'all' in the name, which signifies that all profiles
from that day were plotted.

Some files have 'sub' in the name, which signifies that a subset of
profiles were plotted.

Otherwise, all times appear in the plot.

2\. Site information:

The TEACO2 Doppler lidar was stationed at the general aviation airport
in LaPorte, TX.

LAT 29.66917, LON -95.06417, 7.3 m ASL

3\. Data:

Each profile has 2 header lines

1^st^ header line:

1\. File number on original data tape

2\. Month

3\. Day

4\. Year (year 100 is year 2000)

5., 6., and 7. Hour, minute, and second (in UTC), respectively, of the
start time of the file. If there is more than one profile in a file, all
will carry the same start time as the start time of the file. Each
plan-position indicator (PPI) scan (from which the profiles are derived)
takes approximately 1 minute and 48 seconds to obtain.

8\. Fixed elevation angle, in degrees. For example, if 1.000 is the
fixed angle, the scanner remained at 1E above the horizon while sweeping
in azimuth.

9., 10., 11. Internal housekeeping fields - please disregard

2^nd^ header line:

1\. ALT is the height above ground in kilometers (relative to the lidar)

2\. WIND SPD is wind speed in m/s

3\. WIND DIR is wind direction in degrees from north

4\. SNR is signal-to-noise ratio

5\. % GOOD PTS is the percentage of good points in the profile

6\. WV

7\. RMS ERROR is the root mean square error in m/s

The last 4 columns may be used to threshold the data.

Values used to threshold the data plotted in the files found in the
graphics_files directory:

minimum percentage good points = 17

minimum snr = -35

max wv = 10

max rms error = 1.5

Each individual researcher is free to determine the most convenient way
to threshold the data for their purposes.

4\. Known problems with the data:

From 8/20/00 to 8/22/00 there was a problem with the scanner that
resulted in the elevation angle of the scanner gradually increasing with
time. Once the problem was discovered, the scanner was re-aligned
approximately every hour to minimize the drift, until the problem was
resolved with a replaced part. Known maximum elevation angle errors for
these days are: 4.12E at 2140 UTC on Aug. 20, 4.49E at 1950 UTC on Aug.
21, and 1.43E at 1459 UTC on Aug. 22. This elevation angle drift results
in errors in the calculated height above ground level (the ALT column)
for these days. These errors have not been corrected.

At 2312 UTC on Aug. 31^st^, the scanner elevation angle was 5E too high.

5\. Data use policy:

We request that a proper acknowledgment to the \"NOAA Environmental
Technology Laboratory\" accompany the use of this data in any
publications and presentations. If the use of the data in a publication
constitutes a major or reasonably significant aspect of an article,
co-authorship by an ETL scientist is appropriate; please discuss any
such planned use with the scientist listed below. We welcome
collaborations and will lend our scientific expertise in interpretation
and evaluation of the data.

Lisa Darby, lisa.darby@noaa.gov