Investigations in Pyranometer Design

Beaubien, David J.; Bisberg, A.; Beaubien, Arthur F.

doi:10.1175/1520-0426(1998)015<0677:iipd>2.0.co;2

Cited by 14 publications

(10 citation statements)

References 7 publications

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“…As a protective element for the detector and at the same time a solar radiation diffuser (see Figure 1), a teflon diffusing disk was mounted over the photodetector assembly with a great deal of care to improve its cosine response. To a large extent, this diffuser allows elimination of the cosine error (Michalsky et al, 1995;King et al, 1997;Beaubien et al, 1998). Teflon was used because it is a good diffuser and is also resistant to the elements and ultra-violet (UV) radiation (Lowry et al, 1991;Bernhard and Seckmeyer, 1999), given its capability to diffuse transmitting lights nearly perfectly.…”

Section: Radiation Diffuser and Pyranometer Housingmentioning

confidence: 99%

Construction of a reliable model pyranometer for irradiance measurements

Noudeh¹,

Khazaeli²,

Behravan³

et al. 2010

Afr. J. Biotechnol.

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There is a problem of availability of sufficient and functional instruments for measuring solar radiation in Nigeria due to the high importation costs and maintenance. In order to alleviate this problem, the design, construction and testing of a reliable model pyranometer (RMP001) was done in Mubi, Adamawa State of Nigeria. Detailed instructions were provided for assembly and calibration. Bearing cost, photodiode active-surface and signal-to-noise ratio in mind, the most suitable photodiode for this application was BPW21. The pyranometer was constructed around the photodiode held with a protective plastic case. The CMP3 pyranometer was used as a standard for calibration and comparison. A calibration constant of 5230 ± ± ± ± 0.02 Wm -2 was obtained. The stability of the RMP001 compared favourably with the CMP3 during a day open -sky test giving irradiances of 20.76 and 21.7 Wm -2 for RMP001 and CMP3, respectively, at 5:25 p.m. RMP001 will be used for the collection of authentic irradiance data for comparative evaluation with the theoretical predicted results given by researchers.

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Section: Radiation Diffuser and Pyranometer Housingmentioning

confidence: 99%

Construction of a reliable model pyranometer for irradiance measurements

Noudeh¹,

Khazaeli²,

Behravan³

et al. 2010

Afr. J. Biotechnol.

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“…The broadband albedo is significant in regards to scientific use [6], so it is necessary to design additional spectral albedometers that can operate at ranges between 1100 and 2800 nm. The thermopile detector is often applied to broadband radiation detection, which may be useful in this regard [45,46]. We will focus on the design and performance of the spectral albedometer design at wavelengths greater than 1100 nm, and will continue to carry out observation experiments tailored to heterogeneous surfaces.…”

Section: Discussionmentioning

confidence: 99%

Design of a Novel Spectral Albedometer for Validating the MODerate Resolution Imaging Spectroradiometer Spectral Albedo Product

2018

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Land surface shortwave broadband albedo is a key parameter in general circulation models and surface energy budget models. Multispectral satellite data are typically used to generate broadband albedo products in a three-step process: atmospheric correction, for converting the top-of-atmosphere observations to surface directional reflectance; angular modeling, for converting the surface directional reflectance to spectral albedo of each individual band; and finally, narrowband-to-broadband conversion, for transforming the spectral albedos to broadband albedos. Spectroradiometers can be used for validating surface directional reflectance products and pyranometers or broadband albedometers, for validating broadband albedo products, but spectral albedo products are rarely validated using ground measurements. In this study, we designed a new type of albedometer that can measure spectral albedos. It consists of multiple interference filters and a silicon detector, for measuring irradiance from 400-1100 nm. The linearity of the sensors is 99%, and the designed albedometer exhibits consistency up to 0.993, with a widely-used commercial instrument. A field experiment for measuring spectral albedo of grassland using this new albedometer was conducted in Yudaokou, China and the measurements are used for validating the MODerate Resolution Imaging Spectroradiometer (MODIS) spectral albedos. The results show that the biases of the MODIS spectral albedos of the first four bands are −0.0094, 0.0065, 0.0159, and −0.0001, respectively. This new instrument provides an effective technique for validating spectral albedos of any satellite sensor in this spectral range, which is critical for improving satellite broadband albedo products.

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“…The ACR is an open cavity with no windows and was developed to measure the extended broadband spectrum of the terrestrial direct solar beam irradiance that extends beyond the ultraviolet and infrared bands (i.e., below 0.2 µm and above 50 µm, respectively). On the other hand, pyranometers and pyrheliometers measure broadband shortwave irradiance from approximately 0.3 µm to 3 µm [4] [5] and the silicon-based photovoltaic cells are limited to the spectral range of approximately 0.3 µm to 1 µm. The broadband spectral mismatch of the ACR versus the shortwave radiometers might result in a larger than 1% bias in the radiometers' calibration methods, as shown in Reda, et al 2015 [6].…”

Section: Introductionmentioning

confidence: 99%

Reducing Broadband Shortwave Radiometer Calibration-Bias Caused by Longwave Irradiance in the Reference Direct Beam

Reda¹,

Andreas²,

Dooraghi³

et al. 2017

ACS

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Shortwave radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to consensus reference, maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window that measures the extended broadband spectrum of the terrestrial direct solar beam irradiance, unlike shortwave radiometers that cover a limited range of the spectrum. The difference between the two spectral ranges may lead to calibration bias that can exceed 1%. This article describes a method to reduce the calibration bias resulting from using broadband ACRs to calibrate shortwave radiometers by using an ACR with Schott glass window to measure the reference broadband shortwave irradiance in the terrestrial direct solar beam from 0.3 µm to 3 µm. Reducing the calibration bias will result in lowering the historical solar irradiance by at least 0.9%. The published results in this article might raise the awareness of the calibration discrepancy to the users of such radiometers, and open a discussion within the solar and atmospheric science community to define their expectation from such radiometers to the radiometers' manufacturers and calibration providers.

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Investigations in Pyranometer Design

Cited by 14 publications

References 7 publications

Construction of a reliable model pyranometer for irradiance measurements

Construction of a reliable model pyranometer for irradiance measurements

Design of a Novel Spectral Albedometer for Validating the MODerate Resolution Imaging Spectroradiometer Spectral Albedo Product

Reducing Broadband Shortwave Radiometer Calibration-Bias Caused by Longwave Irradiance in the Reference Direct Beam

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