What makes this station different?

Figure The station in the field. The trees located about 100 m North of the tower were cut at the end of the Summer of 2020.

Logger and sensors

A Campbell Scientific CR6 datalogger with a CDM-A116 analogue imput module is used. The datalogger has both digital and analogue inputs. The anologue to digital conversion (ADC) is done with 24 bits resolution and autoranging. Data is aquired from all sensors except those in the ground once every 5 s and summaries computed and saved at 1 min-, 1 h-, and 1 d intervals. Soil sensors are read less frequently, and summaries saved at 1 h intervals. In the daily data, in addition to means, standard errors, maxima and minima for most variables, and histograms for radiation data, computed in the logger, are also saved. In daily data, times for maxima and minima are also recorded. Each of the sets of summaries, 1 min, 1 h and 1 d, are stored in different tables (storage space) in the logger’s CRBASIC program and downloaded as separate text files. Data are downloaded on site through a USB connection to a laptop computer.

Figure The station in February 2017, before the cross-arm was repositioned. The crossarm is oriented N-S with the N on the right side of the photograph.

Figure View of the station after the sensors were repositioned in May 2020. The long cross-arm was moved higher up and a second, lower cross-arm oriented E-W was added for the weather sensor. Potograph in June 2020

Figure View of the station after the infrared temperature sensors were installed in November 2020 on a third cross-arm.

Radiation sensors are at > 2 m above the ground surface, on a cross arm on the South of the tower, except for the sglux ones that are on the North side at the opposite end of the same cross arm. The weather sensor is at 1.9 m above the ground, at the East end of an East-West cross arm 0.75 m away from the mast. The sensors were relocated in the Spring of 2020, moving the radiation sensors higher up and the weather sensor from the North to the East side of the mast. The station is powered by a battery that is charged by a mains power supply and a solar panel in parallel, ensuring uninterrupted power year-round in spite of the high frequency of measurement, and the heating of some of the sensors during winter time. The table below gives the list of sensors.

Table Sensors in the weather station. signal is how the datalogger receives the information. Sensors with mV (millivolt) output lack built-in amplifier and provide a raw electrical signal. Sensors with V (Volt) output have a built-in analogue amplifier. Signal in ohms (\(\Omega\)) is the sensor’s electrical resistance. SDI-12 is a digital serial communication protocol. In the case of analogue sensors, the digital conversion is done by the datalogger. For digital signals the conversion is done in the sensor. Most SDI-12 “sensors” like the WXT520 “weather sensor” contain sensors for multiple variables. SDI-12 communication allows the data from difference sensors to be sent sequentially using the same wires and logger inputs.
Sensor type make variable qty. signal since
UV-Cosine (UVB) sglux UVB irradiance 1 0-5V May 2020
UV-Cosine (UVA) sglux UVA irradiance 1 0-5V May 2020
UV-Cosine (blue) sglux Blue-Violet irrad. 1 0-5V May 2020
SKR-110 R/FR Skye red irradiance 1 mV June 2017
SKR-110 R/FR Skye far-red irradiance 1 mV June 2017
LI-190 quantum LI-COR PAR (total PPFD) 1 mV January 2016
CS310 CampbellSci PAR (total PPFD) 1 mV June 2021
SMP3 pyramometer Kipp global radiation 1 0-1V January 2016
BF5 Delta-T PAR (total PPFD) 1 0-2.5V June 2017
BF5 Delta-T PAR (diffuse PPFD) 1 0-2.5V June 2017
WXT520 Vaisala Air temperature 1 SDI-12 August 2016
WXT520 Vaisala Air humidity 1 SDI-12 August 2016
WXT520 Vaisala Wind speed 1 SDI-12 August 2016
WXT520 Vaisala Wind direction 1 SDI-12 August 2016
WXT520 Vaisala Atmospheric pressure 1 SDI-12 August 2016
WXT520 Vaisala Precipitation, rain 1 SDI-12 August 2016
WXT520 Vaisala Precipitation, hail 1 SDI-12 August 2016
WXT530 Vaisala Air temperature 1 SDI-12 June 2021
WXT530 Vaisala Air humidity 1 SDI-12 June 2021
WXT530 Vaisala Wind speed 1 SDI-12 June 2021
WXT530 Vaisala Wind direction 1 SDI-12 June 2021
WXT530 Vaisala Atmospheric pressure 1 SDI-12 June 2021
WXT530 Vaisala Precipitation, rain 1 SDI-12 June 2021
WXT530 Vaisala Precipitation, hail 1 SDI-12 June 2021
SoilVUE10 CampbellSci Soil moisture profile 3 SDI-12 May 2020
SoilVUE10 CampbellSci Soil temperature profile 3 SDI-12 May 2020
SoilVUE10 CampbellSci Soil elect. cond. profile 3 SDI-12 May 2020
SoilVUE10 CampbellSci Soil permittivity profile 3 SDI-12 May 2020
CS655 CampbellSci Soil moisture 8 SDI-12
CS655 CampbellSci Soil temperature 8 SDI-12
CS655 CampbellSci Soil elect. cond. 8 SDI-12
CS655 CampbellSci Soil permittivity 8 SDI-12
107 CampbellSci Soil temperature profile 3 ohms August 2020
CSmicro LT02 Optris Surface temperature 2 0-5V November 2020

Figure Hemispherical view from PAR sensor position. Field of view of the PAR sensor. The hemispherical photograph below was taken from sensors’ position and elevation, North at top. Taken in September 2017.

A small grove of birch trees about 100 m to the North of the station were cut in year 2020. They may have affected the wind regime to some extent from start of measurements in 2015 until the Summer of 2020. In spite of the distance to them, the tall buildings around the field are likely to disturb wind direction and speed differently in different parts of the field.

Weather sensor

LI-COR PAR quantum sensor (left) Kipp pyranometer (right)

Diffuse/direct PAR sensor (left) Skye read and far-red sensor (right)

Blue, UVA and UVB sensors (left) Decagon PAR sensors (right)

Non-contact surface temperature sensors

Equipment suppliers

Campbell Scientific

Delta-T Devices

Kipp & zonen

Optris

sglux

Skye Instruments

Vaisala