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Sensor Specs

Picture of a weather station with sensors numbered The following sensor specifications, except sensor heights, are provided by the particular sensor manufacturer:

  1. Total solar radiation (pyranometer)
  2. Soil temperature (thermistor)
  3. Air temperature/relative humidity (HMP35)
  4. Wind direction (wind vane)
  5. Wind speed (anemometer)
  6. Precipitation (tipping-bucket rain gauge)


1. Total solar radiation (pyranometer)
Solar radiation sensor
Sensor: Pyranometer--high stability silicon photovoltaic detector (blue enhanced)
Model: LI200S
Maker: Li-Cor
Height: 2.0 meters
Sensitivity: ±5% error under natural sunlight conditions. Typically 80 micro Ampere per 1000 watts per square meter.
Linearity: Maximum deviation of 1% up to 3000 watts per square meter.
Response time: 10 micro seconds.
Correction: Cosine corrected up to 80 degrees angle of incidence.
Azimuth: ±1% error over 360 degrees at 45 degrees elevation

Sensor: Pyranometer--silicon photodiode detector
Model: SP Lite2
Pyranometer--silicon photodiode detector
Maker: Kipp & Zonen
Height: 2.0 meters
Sensitivity: 60 to 100 micro volts per watt per square meter.
Linearity: <1% up to 1,000 watts per square meter.
Response time: <5 nanoseconds.
Correction: Cosine corrected up to 80 degrees of angle of incidence.


2. Soil temperature (thermistor)
Soil temperature sensor
Sensor: Soil Thermistor--Fenwal Electronic UUT51J1 thermistor in water resistant coating.
Model: 107b
Maker: Fenwal modified by Campbell Scientific Inc.
Height: 15 cm (6 in) below soil surface under irrigated grass.
Accuracy: Worst case ±0.4 degrees C over -33 to 48 degrees C, ±0.5 degrees C at -40 degrees C


3. Air temperature/relative humidity (HMP35)
Air temperature sensor
Sensor: Fenwal Thermistor/HUMICAP H-sensor
Model: HMP35C
Maker: Vaisala modified by Campbell Scientific, Inc.
Height: 1.5 m
Range: 0 to 100% RH, -35 to +50 degrees C
Accuracy: ±2% RH (0-90% RH), ±5% RH (90-100%), ±0.1 °C over -24 to 48 °C range

Sensor: Thermistor -- HygroClip 2 Probe
Model: HC2-S3
Thermistor -- HygroClip 2 Probe
Maker: Rotronic
Height: 1.5 meters
Range: -50 to 100°C, 0 to 100% RH
Accuracy: ±0.1 K at 23°C, °C±5K, ±0.8% RH
Note: Both sensors are enclosed in a 12-plate naturally aspirated radiation shield made by R. M. Young


4. Wind direction (wind vane)
Wind direction sensor
Sensor: 2.0 meters
Model: 024A
Maker: Met-One
Height: 2.0 meters
Range: 0-360 degrees
Output: 0-10 * 10³ Ohms
Threshold: 0.45 m per sec (1 mph)
Accuracy: ±5%
Delay Distance: less than 1.3 m


5. Wind speed (anemometer)
Wind speed sensor
Sensor: Three-cup anemometer utilizing a magnet activated reed switch whose frequency is proportional to wind speed
Model: 014A
Maker: Met-One
Height: 2.0 meters
Range: 0-45 m per sec (0-100 mph)
Threshold: 0.45 m per sec (1 mph)
Gust Survival: 0-53 m per sec (0-120 mph)
Accuracy: 1.5% or 0.11 m per sec (0.25 mph)


6. Precipitation (tipping-bucket rain gauge)
Precipitation sensor
Sensor: Tipping-bucket rain gauge with magnetic reed switch.
Model: TE525MM
Maker: Texas Electronics
Height: 1.0 meters
Orifice: 24.5 cm (9.644 in)
Resolution: 0.1 mm
Accuracy: ±1% at 5 cm per hr or less.