Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

Hodges, G; Michalsky, JJ

doi:10.2172/1020261

Cited by 15 publications

(13 citation statements)

References 4 publications

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“…The Multi-filter Rotating Shadowband Radiometer (MFRSR) established by the US Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility is another widely used instrument to measure spectral irradiance components, aerosol and cloud optical properties (Harrison et al, 1994;Hodges and Michalsky, 2011).…”

Section: Introductionmentioning

confidence: 99%

Algorithms and uncertainties for the determination of multispectral irradiance components and aerosol optical depth from a shipborne rotating shadowband radiometer

et al. 2017

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Abstract. The 19-channel rotating shadowband radiometer GUVis-3511 built by Biospherical Instruments provides automated shipborne measurements of the direct, diffuse and global spectral irradiance components without a requirement for platform stabilization. Several direct sun products, including spectral direct beam transmittance, aerosol optical depth, Ångström exponent and precipitable water, can be derived from these observations. The individual steps of the data analysis are described, and the different sources of uncertainty are discussed. The total uncertainty of the observed direct beam transmittances is estimated to be about 4 % for most channels within a 95 % confidence interval for shipborne operation. The calibration is identified as the dominating contribution to the total uncertainty. A comparison of direct beam transmittance with those obtained from a Cimel sunphotometer at a land site and a manually operated Microtops II sunphotometer on a ship is presented. Measurements deviate by less than 3 and 4 % on land and on ship, respectively, for most channels and in agreement with our previous uncertainty estimate. These numbers demonstrate that the instrument is well suited for shipborne operation, and the applied methods for motion correction work accurately. Based on spectral direct beam transmittance, aerosol optical depth can be retrieved with an uncertainty of 0.02 for all channels within a 95 % confidence interval. The different methods to account for Rayleigh scattering and gas absorption in our scheme and in the Aerosol Robotic Network processing for Cimel sunphotometers lead to minor deviations. Relying on the cross calibration of the 940 nm water vapor channel with the Cimel sunphotometer, the column amount of precipitable water can be estimated with an uncertainty of ±0.034 cm.

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Section: Introductionmentioning

confidence: 99%

Algorithms and uncertainties for the determination of multispectral irradiance components and aerosol optical depth from a shipborne rotating shadowband radiometer

et al. 2017

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“…At the SGP site, aerosol optical depth is routinely observed by the Aerosol Robotic Network (AERONET) Cimel sun photometer (Holben et al, ) and a multifilter rotating shadowband radiometer (Hodges & Mhichalsky, ). We use the AERONET observed aerosol optical depth data for all SGP cases except 4 July 2014 case for which Sun photometer observations are not available.…”

Section: Methodology and Datamentioning

confidence: 99%

Cloud Edge Properties Measured by the ARM Shortwave Spectrometer Over Ocean and Land

2019

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We use the spectrally invariant method to study the variability of cloud optical thickness (τ) and droplet effective radius (r eff ) in transition zones between the cloudy and clear-sky columns observed by Shortwave Array Spectroradiometer-Zenith at the Southern Great Plains Central Facility site (SGP C1) and during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The spectrally invariant method approximates the spectra in the transition zone as a linear combination of definitely clear and definitely cloudy spectra. The slope and intercept of the linear relations characterize τ and r eff in the transition region, respectively. The radiative transfer model simulations show that that (i) the slope of the visible band is positively correlated with τ, while (ii) the intercept of the near-infrared band has a high negative correlation with r eff . We have analyzed 22 cloud edge cases from the SGP and MAGIC and found that from cloud to clear in the transitions, (a) the slopes of the visible band decrease, indicating the decrease of τ toward cloud edges, and (b) the intercepts of the near-infrared band show a much more significant increase at the SGP than from the MAGIC. The results from observed cases suggest that while τ decreases for all cases, the decrease in r eff is much more significant for cloud over land at the SGP site compared to the ocean counterpart during the MAGIC campaign.

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“…The main reason for this is that the instruments for these measurements -the spectroradiometers -are more complex electro-optical systems for field measurements, and calibration procedures and maintenance are difficult to perform routinely in a non-operational network. One example is the MFRSR (Hodges, 1993) USA network, which provides spectral radiation data but only at specific wavelengths. Today, well-known detection systems based on silicon photodiode (CCD) arrays are part of modern spectroradiometers, which are increasingly used, facilitating spectral measurements.…”

Section: Introductionmentioning

confidence: 99%

SSolar-GOA v1.0: a simple, fast, and accurate Spectral SOLAR radiative transfer model for clear skies

2022

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Abstract. The aim of this work is to describe the features of and to validate a simple, fast, accurate, and physically based spectral radiative transfer model in the solar wavelength range under clear skies. The model, named SSolar-GOA (the first “S” stands for “spectral”), was developed to evaluate the instantaneous values of spectral solar irradiances at ground level or at a given altitude of the atmosphere. The model requirements are designed based on the simplicity of the analytical expressions for the transmittance functions in order to be easily replicated and applied by a wide community of users for many different applications (atmospheric and environmental research studies, satellite remote sensing, solar energy, agronomy and forestry, ecology, and others). Although spectral, the model runs quickly and has sufficient accuracy for the evaluation of solar irradiances with a spectral resolution of 1–10 nm. The model assumes a single mixed molecule–aerosol scattering layer where the original Ambartsumian method of “adding layers” in a one-dimensional medium is applied, obtaining a parameterized expression for the total transmittance of scattering. Absorption by the different atmospheric gases follows “band model” parameterized expressions. The input parameters must be realistic and easily available since the spectral aerosol optical depth (AOD) is the main driver of the model. The validation of the SSolar-GOA model has been carried out through comparison with simulated irradiance data from the libRadtran package and with direct and global spectra measured by spectroradiometers. Thousands of spectra under clear skies have been compared for different atmospheric conditions and solar zenith angles (SZA). The SSolar-GOA is validated by a quantitative comparison with libRadtran, showing that it underestimates direct normal, global, and diffuse spectral components with relative differences of +1 % (RMSE % = 4.6–8), +3 % (RMSE % = 5.3–8), and 8 % (RMSE % = 9.3–9.6), respectively, when the SZA varies from 6 to 60∘. Compared with the measured irradiance data of the LI-1800 and ASD spectroradiometers, the relative differences of direct normal and global components are within the overall experimental error, about ±2 %–12 % (RMSE % = 5–8.3), with underestimated or overestimated values. The diffuse component presents the highest degree of relative difference that can reach ±20 %–30 % and RMSE of 25 %–50 %. The relative differences depend strongly on the spectral solar region analysed and the SZA, but the high values of RMSE are due to the artifice generated by the different spectral resolution of the absorption coefficients of both models. Model approach errors combined with calibration instrument errors may explain the observed differences. The SSolar-GOA v1.0 is implemented in Python and open-source licensing.

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Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

Cited by 15 publications

References 4 publications

Algorithms and uncertainties for the determination of multispectral irradiance components and aerosol optical depth from a shipborne rotating shadowband radiometer

Algorithms and uncertainties for the determination of multispectral irradiance components and aerosol optical depth from a shipborne rotating shadowband radiometer

Cloud Edge Properties Measured by the ARM Shortwave Spectrometer Over Ocean and Land

SSolar-GOA v1.0: a simple, fast, and accurate Spectral SOLAR radiative transfer model for clear skies

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