Pyrgeometers / Four-Component Radiometer
In meteorological applications, infrared or long wavelength radiations are electromagnetic radiations with a wavelength longer than 3.0 µm. Long wave radiations physically relate to temperature and are emitted by all objects on earth. It corresponds to the spectral range beyond the shortwave spectrum of the sun which covers the spectral range 300 nm - 3µm (99.5% of the total solar energy).
EKO's pyrgeometers and net radiometers are used for meteorological observations of atmospheric radiations (radiations from clouds, water vapor, CO2 etc.) and the net radiation exchange between the earth and the atmosphere. Net total irradiance (shortwave + longwave) is typically measured by 4 component net radiometers or single component pyradiometers which have a single detector covering the full range. Pyrgeometers measure the long wave down welling radiation by means of a single detector facing the atmosphere. The Net longwave and down welling radiation can be determined by calculation.
|Specifications (typical)||MS-202 / MS-202F||MF-11 / MF-11A||MR-60|
|ISO 9060 classification||N/D||N/D||N/D
|Response time 95% (sec)||9||N/S
|Zero offset - Window heating (1000W/m²) (*Corrected)||*+ 5 W/m²||N/S||+25|
|Zero offset - Temperature change (5K/hr)||± 2 W/m²||N/S||4
|Non-stability (change/year)||± 0.5 %||N/S||± 1 %
|Non-linearity (at 1000W/m²)||± 1 %||
|Directional response (at 1000W/m²)||± 10 W/m²||N/S||N/S|
|Spectral selectivity (0.35-1.5µm)||- 2.1 %||N/S||N/S
|Temp. response (for 50°C band)||< ± 1 %||N/S||< 6%|
|Tilt response (at 1000W/m²)||< ± 0.2 %||N/S||2%|
|Sensitivity (µV/W/m²)||~4||~7 (~25 Night time)||~7|
|Impedance (Ω)||~300||~90|| 20 ~ 140
|Operating temperature, °C||- 40 to +80||-15 to +40||- 40 to +70
|Wavelength range (> 50% transmittance)||4 to 50 µm
||0.3 to >30 µm||0.3 to 50 µm|
|Temperature compensation circuit||Lithium battery 3V, CR123 Battery life 7months||N/A||N/A|
|Blower Fan for model MS-202F)||Blower fan
AC100, 110, 220V (50/60Hz) DC12,24V
|Blower fan VAC 100||N/A|
Prediction of minimum temperature and frost damage is a common method and important application in the field of agriculture like outdoors crop growth. In particular those areas where ...
Indoors Calibration Procedure Pyranometer
The pyranometer is calibrated against a calibrated reference pyranometer using a 1000 W/m2 Class AAA sun simulator as source. The pyranometer is situated on a horizontal table and alligned to the optical axis of a normal incidence light source. By alternating the position of the calibrated reference pyranometer with the test pyranometer the output signal of both pyranometers is recorded and used to solve the equation of the unknown sensitivity variable. Since the operating conditions are relatively constant (e.g. ambient temperature and normal incidence irradiance), the pyranometer uncertainty figure is determined by taking into account the sensitivity uncertainty of the reference pyranometer and the max. deviation of the incident irradiance between two measurement intervals.
Outdoors Calibration Procedure Pyrgeometer
The pyrgeometer is calibrated side by side against a calibrated reference pyrgeometer. Both sensors are horizontally mounted on a stable platform and connected to a data acquisition system. For a period of x days global IR radiation is measured based on 1 minute average values with a minimum of 300 datapoints. The calibration value of the subjected pyrgeometer is obtained by multiplying the sensitivity value of the reference pyrgeometer with the averaged ratio of the measured global IR radiation data. To improve the calibration accuracy and mimimize the measurement uncertainty several operating criteria are applied. The criteria for the operating conditions are indicated like ambient temperature, min. global IR radiation and min. solar elevation angle are applied to minimize the overall uncertainty in the calibration. The pyrgeometer uncertainty figure is statistically calculated based on a standard deviation of (1.96σ), which means that 95% of the measured global irradiance values agree with the reference pyrgeometer.
Frequently Asked Questions
The sensitivity of the solar sensor will slightly deviate with time when it is exposed to solar radiation. Therefore it is advised to re-calibrate the sensor every two years. For calibration ...