Pyranometer

Brewer and Field Spec spectrophotometers and pyranometers) and LOWTRAN 7 code (6) results. In this way, this model can be also a useful tool for a wide range of applications in Visible and Infrared spectra, mainly for data validation and for the simulation of the radiation changes due to changes in the atmospheric chemical composition. 

Pyrheliometer is an instrument that measures only the direct radiation from the solar disk itself, without bouncing off clouds or the atmosphere. Concentrating solar collectors utilize only this part of the total solar radiation. Its measurement gives an indication of the clearness of the sky. The normal incident pyrheliometer (NIP) measures this form of radiation. A tracker, called the equatorial mount, is used to keep the NIP pointed at the sun. The difference between the NIP and the total pyranometer readings is referred to as the diffuse solar radiation. 

Fig. 15. Spectral response of thermopile pyranometer measuring total solar radiation is shown with thick black line. Spectral radiance (brightness) of the sky dome (blue line). The cut-off at 3000 nm means the radiometer will not respond to the infrared sky radiation that peaks at 7000...

Knowledge of the optical properties of materials in relation to the solar spectrum is also important in measuring broadband solar radiation. For instance, a pyranome ter used to monitor total solar radiation for a renewable energy system has a spectral response (due to the special glass dome protecting the detector) that does not respond to the thermal infrared radiation of the sky beyond 3000 nm, as shown in Fig. 15. Flowever, there will be thermal infrared radiation exchanged between the radiometer and the sky dome, which will influence the measurement performance of the pyranometer.9... 

I. Reda, J. Hickey, C. Long, D. Myers, T. Stoffel, S. Wilcox, J. J. Michalsky, E. G. Dutton, and D. Nelson, Using a blackbody to calculate net-longwave responsivity of shortwave solar pyranometers to correct for their thermal offset error during outdoor calibration using the component sum method, Journal of Atmospheric and Oceanic Technology 22 1531 (2005). 

All radiation measurements have always been carried out and processed on the appropriate international pyrheliometric scale. The instruments are regularly calibrated by comparison with the sun as a source to the national pyrheliometer (AHF of The Eppley) and pyranometer (CM 11 of Kipp and Zonen) standards, participating in the periodically organized international or regional comparisons. They are referred to as the World Radiometric Reference (WRR 1980). 

Figure 4. A comparison of the downward and upward migrations of Daphnia catawba in the presence and absence of UVR. There were three UV-transparent columns and three UV-opaque columns. Each column was suspended 10 cm below the surface of Lake Giles, a high-UV lake located in northeastern PA, USA. The downward experiment was conducted on 14 July 2000 and the upward on 2 August 2000. Mean solar irradiance was measured with a LICOR model LI-200SA pyranometer near solar noon (1300 h) when the experiments were conducted. Mean solar irradiance equaled 659 Wm on 14 July 2000 and 694 W on 2 August 2000.

Pyranometer - A device used to measure total incident solar radiation (direct beam, diffuse, and reflected radiation) per unit time per unit area. 

ASTM E424 Standard Test Method for Solar Energy Transmittance and Reflectance (Terrestrial) of Sheet Materials. Used to determine solar energy transmittance and reflectance of materials in sheet form using one of two procedures. Method A, the referee method, is applicable for both transmittance and reflectance and uses a spectrophotometer. Methods is applicable only for measurement of transmittance and uses a pyranometer in an enclosure and the sun as the energy source. Both test methods have given essentially equivalent results for those materials studied by the task group who prepared the method. 

ASTM G 183 [390] Standard Practice for Field Use of Pyranometers, Pyrheliometers and UV Radiometers... 

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