TA-41 Station Description

Alternate Name(s): Los Alamos Canyon

Measurements:
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.

Data Type Record Begins Record Ends
15-min dataNovember 22, 1993

(still active)

24-h data November 22, 1993

(still active)

Site Description:
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:
Coordinate System x y
NAD 27 State Plane Coordinates (ft) 486399 1774216
UTM, Zone 13 (m) 382964.85 3971015.85
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.

Data Quality:

General Remarks
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.

Wind Variables
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.

Precipitation-related Variables
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 normal.

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.