Surface Meteorological Station - UND 17m, (3) Sonics 3m 10m 17m, (2) T/RH 3m 17m, Physics site-2 - Raw Data

**Overview**

The data included features wind, temperature, and turbulence measurements.

**Data Details**

Each met station (met.z18, met.z19, met.z21, and met.z23) consists of multiple levels of three-dimensional ultrasonic anemometers, RM Young 81000 (sampling frequency = 20 Hz), and temperature/relative humidity probes, Rotronics HC2S3 (sampling frequency = 1 Hz). The HC2S3 probes were housed in radiation shields to protect them from thermal radiation, and they were adequately ventilated. Moreover, an infrared gas analyzer (LI-7500 Open Path CO~2/H~2~O Analyzer) was collocated at 3-meter height at met.z18 (sampling frequency = 20 Hz) in a second phase of the experiment (June 2016).
Raw data are collected by Campbell CR3000 dataloggers and successively parsed into 15-minutes data files. For each met station, multiple data files are outputted with each data file corresponding to a certain type of instrument and a specific measurement height. The types of instrument and measurement heights are specified by the name of the data file itself. For example, met station met.z19 consists of sonic anemometers measurements at 3-, 10-, and 17-meter height and temperature/relative humidity measurements at 3- and 17-meter height. Therefore, the following data files are outputted:

3m sonic anemometer sample file name:
met.z19.00.20160502.171500.son03m.dat

10m sonic anemometer sample file name:
met.z19.00.20160502.171500.son10m.dat

17m sonic anemometer sample file name:
met.z19.00.20160502.171500.son17m.dat

3m T-RH sensor sample file name:
met.z19.00.20160502.171500.trh03m.dat

17m T-RH sensor sample file name:
met.z19.00.20160502.171500.trh17m.dat

Note that in the "Primary Measurements/Variables" section, the variables sonic_u-wind, sonic_v-wind, sonic_w-wind represent the orthogonal u, v, and w wind velocities outputted by the sonic RM Young 81000, oriented with u-axis aligned east-west
and v-axis aligned north-south. In this orientation, +u values
= wind from the east, and +v values = wind from the north. Wind from below (updraft) = +w.

Instruments' manuals and dataset samples are provided as attachments.

**Data Quality**

Raw data: no quality control (QC) is applied. Data are visually inspected at least weekly.

**Uncertainty**

1. RM Young 81000 Ultrasonic Anemometer Measurements
* Anything that blocks the acoustic signal path will degrade the measurement.
* If the path is blocked sufficiently, measurements cannot
be made. The RM Young 81000 can make accurate measurements in driving rain, but light mist or heavy fog can allow droplets to accumulate on the transducer faces and block the measurement.
* Measurements may be made in driving snow, although frost and
snow that adheres to the transducer face may block the measurement. Similarly, freezing rain on the transducer face may block the measurement.

2. Rotronics HC2S3 Temperature and Relative Humidity Measurement
* This sensor requires minimal maintenance, but dust, debris, and salts on the filter cap may degrade sensor performance. Because of the remote location and difficulties in climbing the met towers, no maintenance of these sensors was performed during the field experiment.

3. Licor LI-7500 Measurement
* The LI-7500 optical windows should be cleaned when necessary (by checking the diagnostic values).
* Rain, snow, fog, condensation, or dust deposition on the optical path of the instrument may affect the gas analyzer's performance and lead to less consistent/missing measurements. Because of the remote location and difficulties in climbing the met towers, no maintenance of these sensors was performed during the field experiment.