TA-41 Station Description
Alternate Name(s): Los Alamos Canyon
The TA-41 station consists of a 23-m tower instrumented for wind at two levels
and near-surface instrumentation for temperature and shortwave irradiance. See
Table 13.4 in the Meteorological
Monitoring Plan for measurement details and in Table 13.3 in the same
document for definitions of variables.
|15-min data||November 22, 1993
|24-h data ||November 22, 1993
The TA-41 station is located at the bottom of Los Alamos Canyon. At this
location, the canyon has an east-west orientation and is approximately 100 m
deep and 300 m wide. The south canyon side-wall is thickly forested with
Ponderosa pine, the north side-wall is sparsely vegetated. The canyon floor
tilts 1.4 degrees to the east in the vicinity of the tower. The fetch for
down-canyon flow is over the paved road along the bottom of the canyon. The
fetch for up-canyon flow is over scattered ponderosa pine.
Location and Elevation:
|NAD 27 State Plane Coordinates (ft) ||486399
|UTM, Zone 13 (m) ||382964.85||
|Longitude & Latitude (d, m, s)||-106° 17' 47"
||35° 52' 35"
Station elevation is 6914 (2107.9 m) above sea level.
The tower is LANL structure no. TA-41-0064.
Nearly all suspect data have been replaced with an asterisk (*). Occasionally
you will see days on which all the 15-min data appear good, but some of the 24-h
summary values are missing. Lightning strikes, momentary power outages, or the
need to reload the datalogger program may be the cause. In these cases, you can
estimate a 24-h value from the 15-min data.
See Section C.1.b and c of the Meteorological Monitoring Plan for
details on sampling and general remarks concerning accuracy.
Qualifying remarks are organized by data type (for example, wind, atmospheric
state, etc.), and we use our standard variable names, as defined in Table 13.3 of the
Meteorological Monitoring Plan.
The measurement of the vertical velocity (w) has been multiplied by 1.25
to correct for the non-cosine response of the propeller. All quantities derived
from the w signal include this correction. The w signal is
occasionally affected by wet snow and ice. Although we have attempted to edit
the data when this happens, you will occasionally see periods of several hours
when w and its standard deviation (sdw) go to zero during the
winter; a frozen propeller is the cause.
Most of the instantaneous wind gust directions (dirgst) are erroneous.
However, directions for the 1-min wind gusts (dirgst) are correct.
Atmospheric State Variables
No known problems.
No known problems.
Radiative Energy Variables
During and for some time after periods of snow or frost formation, the dome of
the upward looking pyranometer may become snow or ice covered. In such instances
the short-wave irradiance (swdn) is diminished. Our editing has not been
consistent: In portions of the record we attempted to remove these snow and
frost effects and in other portions we decided not to edit. In general, it is
difficult to decide when the melting is complete and the signal is back to
As a result of a change in the calibration standard used by the manufacturer,
measurements of swdn are 5% too large from the beginning of the record to
1030 MST on February 22, 1995.