Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation with a Correction for Thermal Offset Errors

Dutton, Ellsworth G; Michalsky, Joseph; Stoffel, T.; Forgan, Bruce; Hickey, J. R.; Nelson, Don; Alberta, Timothy L.; Reda, Ibrahim

doi:10.1175/1520-0426(2001)018<0297:mobdsi>2.0.co;2

Cited by 143 publications

(183 citation statements)

References 24 publications

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“…2) is more complicated; guidance on its (more or less intrusive) direct measurement during daytime (Bush et al, 2000;Dutton et al, 2001;Ji and Tsay, 2010;Michalsky, 2005;Philipona, 2002), as well as its correction using other measured variables (Dutton et al, 2001;Haeffelin et al, 2001;Sanchez et al, 2015), is provided in previous studies. A recent study by Sanchez et al (2015) concludes, based on capping experiments, that observed daytime thermal offsets, for both global and diffuse measurements, are highest correlated with the diffuse fraction of the incoming solar irradiance.…”

Section: Shortwave Fluxescontrasting

confidence: 88%

“…A recent study by Sanchez et al (2015) concludes, based on capping experiments, that observed daytime thermal offsets, for both global and diffuse measurements, are highest correlated with the diffuse fraction of the incoming solar irradiance. These authors highlight, in agreement with earlier work by Dutton et al (2001), the correlation with the ambient air temperature as well as with the net IR signal from a collocated pyrgeometer.…”

Section: Shortwave Fluxesmentioning

confidence: 99%

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The Austrian radiation monitoring network ARAD – best practice and added value

et al. 2016

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Abstract. The Austrian RADiation monitoring network (ARAD) has been established to advance the national climate monitoring and to support satellite retrieval, atmospheric modeling and the development of solar energy techniques. Measurements cover the downward solar and thermal infrared radiation using instruments according to Baseline Surface Radiation Network (BSRN) standards. A unique feature of ARAD is its vertical dimension of five stations, covering an altitude range between about 200 m a.s.l (Vienna) and 3100 m a.s.l. (BSRN site Sonnblick). The paper outlines the aims and scopes of ARAD, its measurement and calibration standards, methods, strategies and station locations. ARAD network operation uses innovative data processing for quality assurance and quality control, utilizing manual and automated control algorithms. A combined uncertainty estimate for the broadband shortwave radiation fluxes at all five ARAD stations, using the methodology specified by the Guide to the Expression of Uncertainty in Measurement indicates that relative accuracies range from 1.5 to 2.9 % for large signals (global, direct: 1000 W m −2 , diffuse: 500 W m −2 ) and from 1.7 to 23 % (or 0.9 to 11.5 W m −2 ) for small signals (50 W m −2 ) (expanded uncertainties corresponding to the 95 % confidence level). If the directional response error of the pyranometers and the temperature response of the instruments and the data acquisition system (DAQ) are corrected, this expanded uncertainty reduces to 1.4 to 2.8 % for large signals and to 1.7 to 5.2 % (or 0.9-2.6 W m −2 ) for small signals. Thus, for large signals of global and diffuse radiation, BSRN target accuracies are met or nearly met (missed by less than 0.2 percentage points, pps) for 70 % of the ARAD measurements after this correction. For small signals of direct radiation, BSRN targets are achieved at two sites and nearly met (also missed by less than 0.2 pps) at the other sites. For small signals of global and diffuse radiation, targets are achieved at all stations. Additional accuracy gains can be achieved in the future through additional measurements, corrections and a further upgrade of the DAQ. However, to improve the accuracy of measurements of direct solar radiation, improved instrument accuracy is needed. ARAD could serve as a useful example for establishing state-of-the-art radiation monitoring at the national level with a multiple-purpose approach. Instrumentation, guidelines and tools (such as the data quality control) developed within ARAD are intended to increase monitoring capabilities of global radiation and thus designed to allow straightforward adoption in other regions, without high development costs.

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Section: Shortwave Fluxescontrasting

confidence: 88%

Section: Shortwave Fluxesmentioning

confidence: 99%

The Austrian radiation monitoring network ARAD – best practice and added value

et al. 2016

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“…The radiometer offsets were routinely measured by covering the radiometers with an opaque cover just before and after the science mission (Dutton et al, 2001). This correction was generally a few watts per square metre or less.…”

Section: Appendix a Data Correction Proceduresmentioning

confidence: 99%

Albedo, atmospheric solar absorption and heating rate measurements with stacked UAVs

Ramana

Ramanathan

Kim

et al. 2007

Quart J Royal Meteoro Soc

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This paper reports unique measurements of albedo, atmospheric solar absorption, and heating rates in the visible (0.4 to 0.7 µm) and broadband (0.3 to 2.8 µm) spectral regions using vertically stacked multiple lightweight autonomous unmanned aerial vehicles (UAVs). The most significant finding of this study is that when absorbing aerosols and water vapour concentrations are measured accurately and accounted for in models, and when heating rates are measured directly with stacked aircraft, the simulated clear sky heating rates are consistent with the observed broadband heating rates within experimental errors (about 15%). We conclude that there is no need to invoke anomalous or excess absorption or unknown physics in clear skies.Aerosol-radiation-cloud measurements were made over the tropical Indian Ocean within the lowest 3 km of the atmosphere during the Maldives Autonomous UAV Campaign (MAC). The UAVs and ground-based remote sensing instruments determined most of the parameters required for calculating the albedo and vertical distribution of solar fluxes. The paper provides a refined analytical procedure to reduce errors and biases due to the offset errors arising from mounting of the radiometers on the aircraft and due to the aircraft attitude. Measured fluxes have been compared with those derived from a Monte-Carlo radiative transfer algorithm which can incorporate both gaseous and aerosol components. Under cloud-free conditions the calculated and measured incoming fluxes agree within 2-10 W m −2 (<1%) depending upon the altitudes. Similarly, the measured and calculated reflected fluxes agreed within 2-5 W m −2 (<5%). The analysis focuses on a cloud-free day when the air was polluted due to long-range transport from India, and the mean aerosol optical depth (AOD) was 0.31 and mean single scattering albedo was 0.92. The UAV-measured absorption AOD was 0.019 which agreed within 20% of the value of 0.024 reported by a ground-based instrument. The observed and simulated solar absorption agreed within 5% above 1.0 km and aerosol absorption accounted for 30% to 50% of the absorption depending upon the altitude and solar zenith angle. Thus there was no need to invoke spurious or anomalous absorption, provided we accounted for aerosol black carbon. The diurnal mean absorption values for altitudes between 0.5 and 3.0 km above mean sea level were observed to be 41 ± 3 W m −2 (1.5 K/day) in the broadband region and 8 ± 2 W m −2 (0.3 K/day) in the visible region. The contribution of absorbing aerosols to the heating rate was an order of magnitude larger than the contribution of CO 2 and one-third that of the water vapour. In the lowest 3 km of the tropical atmosphere, aerosols accounted for more than 80% of the atmospheric absorption in the visible region.

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“…For the downward solar flux, we use the sum of a direct irradiance and a shaded diffuse measurement. The latter is made using an Eppley black and white radiometer, which requires no thermal offset correction [Dutton et al, 2001;Long et al, 2001]. The upward solar flux is measured using a downward facing radiometer mounted on a 10-m tower.…”

Section: The Arese II Datamentioning

confidence: 99%

Quantifying the magnitude of anomalous solar absorption

2003

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[1] The data set from ARESE II, sponsored by the Atmospheric Radiation Measurement Program, provides a unique opportunity to understand solar absorption in the atmosphere because of the combination of three sets of broadband solar radiometers mounted on the Twin Otter aircraft and the ground based instruments at the Atmospheric Radiation Measurement (ARM) Southern Great Plains facility. In this study, we analyze the measurements taken on two clear-sky days and three cloudy days and model the solar radiative transfer in each case with two different models. On the two clear days, the calculated and measured column absorptions agree to better than 10 W m À2 , which is about 10% of the total column absorption. Because both the model fluxes and the individual radiometer measurements are accurate to no better than 10 W m À2, we conclude that the models and measurements are essentially in agreement. For the three cloudy days, the model calculations agree very well with each other and on 2 of the 3 days agree with the measurements to 20 W m À2 or less out of a total column absorption of more than 200 W m À2 , which is again an agreement at better than 10%. On the third day, the model and measurements agree to either 8 or 14% depending on which value of surface albedo is used. Differences exceeding 10% represent a significant absorption difference between model and observations. In addition to the uncertainty in absorption due to surface albedo, we show that including aerosol with an optical depth similar to that found on clear days can reduce the difference between model and measurement by 5% or more. Thus we conclude that the ARESE II results are incompatible with previous studies reporting extreme anomalous absorption and can be modeled with our current understanding of radiative transfer.

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Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation with a Correction for Thermal Offset Errors

Cited by 143 publications

References 24 publications

The Austrian radiation monitoring network ARAD – best practice and added value

The Austrian radiation monitoring network ARAD – best practice and added value

Albedo, atmospheric solar absorption and heating rate measurements with stacked UAVs

Quantifying the magnitude of anomalous solar absorption

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