Readme file for Los Alamos National Laboratory URBAN2000 meteorological data.

These data have been processed and calibrated.  For use, please cite: The Salt Lake
City DOE CBNP URBAN Experiment of Fall 2000: LANL Urban Wind and Temperature
Measurements, LA-UR-01-950, February 2001.

These data were obtained from six meteorology stations deployed in downtown Salt
Lake City from October 1 through October 27, 2000.  Each station contained a 2-D
Handar sonic anemometer and two thermistors.  Five of the stations were located on
roofs; the sixth, identified as Green(500), was mounted on a light pole in the
parking lot between the City Centre building and the Heber-Wells building.  For the
five rooftop stations the anemometer was mounted approximately 3.5m above the
surface and the two thermistors were mounted in radiation shields approximately 0.6m
and 2m above the surface.  The two thermistors for the Green(500) unit dangled at
the height of the datalogger and were not shielded.  Only the nighttime temperatures
at this unit would be considered to be useful data.  Exact location and height data
for the six stations are given below.  UTMX and UTMY coordinates are in meters.

Sensor 100(white) main roof of City Centre (10 floors)
utmx=425212 utmy=4512628 (NAD83)
Roof ht: 40.24m
anemometer ht: 3.44m
temp1 ht: 0.59m
temp2 ht: 1.77m

Sensor 200(black) penthouse roof of Federal Bldg
utmx=425105 utmy=4513235 (NAD83)
Roof ht: 42.79m
anemometer ht: 3.45m
temp1 ht: 0.60m
temp2 ht: 2.0m

Sensor 300(yellow) roof of NW wing of City Centre
utmx=425180 utmy=4512665 (NAD83)
Roof ht: 13.61m
anemometer ht: 3.46m
temp1 ht: 0.59m
temp2 ht: 2.0m

Sensor 400(red) penthouse roof of Heber-Wells
utmx=425212 utmy=4512743 (NAD83)
Roof ht: 34.62m
anemometer ht: 3.47m
temp1 ht: 0.60m
temp2 ht: 2.0m

Sensor 500(green) City Centre parking lot
utmx=425200 utmy=4512678 (NAD83)
Roof ht: N/A
anemometer ht: 3.81m
temp1 ht: 2.6m
temp2 ht: 2.6m

Sensor 600(orange) roof of SE wing of City Centre
utmx=425232 utmy=4512597 (NAD83)
Roof ht: 13.61m
anemometer ht: 3.60m
temp1 ht: 0.60m
temp2 ht: 2.0m

All files for a date are in the directory for that date.  Directories with data
from an Intensive Operations Period (IOP) are indicated by both date and IOP
number. The files in each directory are named by the station ID and the date on
which the data file was initiated.  For instance, 22_REDp.TXT is the data from the
Red(400) station on the Heber-Wells building with a start time on Oct. 22 (MDT).
"p" indicates that the data has been processed.  A number of files include an A or B
designation, for instance, 17A_REDp.TXT and 17B_REDp.TXT.  This indicates that both
files were initiated on Oct. 17, the A file at an earlier time than the B file.

Data were logged at one-second intervals.  The data in the files are comma
delimited and are arranged by the following columns.

Date and time (MDT) - 2 columns
Date and time (UTC) - 2 columns
t - elapsed time in seconds from the start of the file.
u - E-W component of wind velocity in m/s (+u means flow towards the east).
v - N-S component of wind velocity in m/s (+v means flow towards the north).
ws - wind speed in m/s.
wd - wind direction in degrees (0¡ or 360¡ is a wind from the north, 90¡ is a
     wind from the east).
temp1 - air temperature (not potential temperature) in degrees C at the lower
     thermistor.
temp2 - air temperature (not potential temperature) in degrees C at the upper
     thermistor.

Data processing consisted of converting the raw wind data from mph to m/s and
recomputing the u and v components.  Calibration of the sonic anemometers showed
that all measurements lay within the quoted instrumental uncertainty so no
adjustments were made.  The thermistors were calibrated against a high-precision
transfer standard thermistor in water baths.  The thermistors uniformly read from
0.2 to 0.4 deg high so the processed data has been adjusted accordingly.  One of
the Green station thermistors (temp1) was damaged after the experimental campaign
and could not be calibrated.  Since eight of the eleven thermistors that were
calibrated had an offset of 0.3 deg, this offset was used as a calibration value
for this thermistor.

There are a few files in which there are some dropouts in one or the other of the
temperature measurements.  The wind data are still valid at these times. The dropped
readings are indicated by temperature readings that are zero or negative.  The
actual temperature never dropped that low in Salt Lake City during the experimental
period.

The data within a given file can be analyzed for turbulence statistics, but the
files cannot be compared one to another on a second-by-second basis for the
following reasons. The procedures to synchronize time from time server to laptop to
datalogger were not followed consistently and the datalogger clocks tended to drift
a few seconds (typically from 2 to 8) between resynchronizations. It was discovered
that the dataloggers tended to oversample an average of 2-3 times per hour over the
first six hours of measurement. Since the timestamp in the data files is created by
software that assumes a constant one-second sampling interval, there is a cumulative
error of 12-18 seconds over a six-hour sampling period. If these data are used for
the conventional 10-minute wind averages, the aforementioned errors will be
relatively small and comparisons may be made between our sites or between these data
and other URBAN data.

After six hours of measurement the oversampling rate on the Yellow(300) and
Green(500) units drops to an average of 0-2 per hour so the additional cumulative
error for the full measurement period is small and the data files from these units
are included in their entirety. At 9 to 10 hours the other four units began to
exhibit significant undersampling. Until these data files can be examined further,
we felt that it was conservative to release only the first six hours of data from
each file for these instruments.

More information about the measurement campaign, the instruments, the data, and
calibration is available in the data report referenced below.

G.E. Streit, E.R. Pardyjak, M.J. Brown, D.S. DeCroix, T.N. McPherson, and W.S.
Smith, The Salt Lake City DOE CBNP URBAN Experiment of Fall 2000: LANL Urban Wind
and Temperature Measurements, LA-UR-01-950, February 2001.

For questions please email Jerry Streit at ges@lanl.gov