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Norman G. Loeb, Seiji Kato, Konstantin Loukachine, and Natividad Manalo-Smith

provide highly accurate shortwave (SW), longwave (LW), and infrared window (WN) radiance measurements and top-of-atmosphere (TOA) radiative flux estimates globally at a 20-km spatial resolution. These data, together with coincident cloud and aerosol properties inferred from the Moderate Resolution Imaging Spectroradiometer (MODIS), provide a consistent cloud–aerosol–radiation dataset for studying clouds and aerosols, and their influence on the ERB. One of the challenges involved in producing ERB

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Igor Podgorny, Dan Lubin, and Donald K. Perovich

. Vogelmann , 2011 : The influence of mixed-phase clouds on surface shortwave irradiance during the Arctic spring . J. Geophys. Res. , 116 , D00T05 , https://doi.org/10.1029/2011JD015761 . Lubin , D. , P. Ricchiazzi , A. Payton , and C. Gautier , 2002 : Significance of multidimensional radiative transfer effects measured in surface fluxes at an Antarctic coastline . J. Geophys. Res. , 107 , 4387 , https://doi.org/10.1029/2001JD002030 . 10.1029/2001JD002030 Marshak , A. , and A. B

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Xianglei Huang, Norman G. Loeb, and Huiwen Chuang

measurements and their application in model evaluation: Clear sky over the tropical oceans . J. Geophys. Res. , 113 , D09110 , doi:10.1029/2007JD009219 . Huang, X. L. , Loeb N. G. , and Yang W. Z. , 2010 : Spectrally resolved fluxes derived from collocated AIRS and CERES measurements and their application in model evaluation: 2. Cloudy sky and band-by-band cloud radiative forcing over the tropical oceans over the tropical oceans . J. Geophys. Res. , 115 , D21101 , doi:10.1029/2010JD013932

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Wenjun Tang, Kun Yang, Jun Qin, Jun Li, and Jiangang Ye

-HXG, with the adjusted all-sky SSR products from the CERES products (SYN1deg-day and SYN1deg-1hour, edition 4.1), which have a spatial resolution of 1° × 1°. We chose to look at the CERES SSR product because it is generally more accurate than the GWEWX/SRB and ISCCP-FD SSR products ( Rutan et al. 2015 ). Radiative fluxes are calculated for the CERES SYN1deg with the Fu–Liou radiative transfer model ( Fu and Liou 1993 ), using cloud products from MODIS and from geostationary satellite sensors

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F. Tornow, H. W. Barker, Velázquez Blázquez, C. Domenech, and J. Fischer

broadband radiative transfer models act on retrieved cloud and aerosol properties, estimated top-of-atmosphere (TOA) fluxes for domains with areas 100 km 2 will be, on average, within ±10 W m −2 of fluxes inferred from radiances measured by its Broadband Radiometer (BBR; see Illingworth et al. 2015 ). This “radiative closure assessment” experiment has been a central driver to the overall design of the EarthCARE mission. The BBR will measure TOA filtered radiances at nadir and two along-track oblique

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F. Tornow, C. Domenech, and J. Fischer

radiometer (BBR; e.g., Wallace et al. 2009 ; Caldwell et al. 2017 ) observing nadir as well as along track forward and backward (both at 55° viewing zenith angle). Apart from monitoring TOA fluxes, the mission will conduct a radiative closure assessment, comparing BBR-derived longwave (LW) and shortwave (SW) flux estimates with simulated fluxes. Broadband simulations will act on active–passive retrievals of cloud and aerosol properties for ~1-km 2 nadir columns ( Barker et al. 2011 ). Agreement

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Daniela Meloni, Claudia Di Biagio, Alcide di Sarra, Francesco Monteleone, Giandomenico Pace, and Damiano Massimiliano Sferlazzo

1. Introduction Longwave radiation (LW) is a key component of the energy balance of the earth–atmosphere system and is affected by greenhouse gases and clouds, by far the most important parameters in climate change studies. Estimates of LW irradiances are generally based on parameterizations, both for cloud-free and all-sky conditions ( Allan et al. 1999 ; Ruckstuhl et al. 2007 ; Dupont et al. 2008 , among others), or radiative transfer calculations, while measurements are not as conventional

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Bijoy Vengasseril Thampi, Takmeng Wong, Constantin Lukashin, and Norman G. Loeb

emitted thermal radiative fluxes ( Wielicki et al. 1995 ). CERES instruments measure broadband radiances in the shortwave (SW, 0.2–5 µ m), longwave (LW, 5–200 µ m), and window (WN, 8–12 µ m) band regions over 20-km footprints at nadir. These CERES-measured directional radiances are converted to radiant fluxes using angular distribution models (ADMs). Compared to previously developed ADMs used for the Earth Radiation Budget Experiment (ERBE) mission ( Suttles et al. 1988 ), the accuracy of the new

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Seung-Hee Ham, Seiji Kato, and Fred G. Rose

://doi.org/10.1029/2010GL044094 . 10.1029/2010GL044094 Doelling , D. R. , and Coauthors , 2013 : Geostationary enhanced temporal interpolation for CERES flux products . J. Atmos. Oceanic Technol. , 30 , 1072 – 1090 , https://doi.org/10.1175/JTECH-D-12-00136.1 . 10.1175/JTECH-D-12-00136.1 Fu , Q. , and K.-N. Liou , 1993 : Parameterization of the radiative properties of cirrus clouds . J. Atmos. Sci. , 50 , 2008 – 2025 , https://doi.org/10.1175/1520-0469(1993)050<2008:POTRPO>2.0.CO;2 . 10

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Joseph Michalsky, Ellsworth G. Dutton, Donald Nelson, James Wendell, Stephen Wilcox, Afshin Andreas, Peter Gotseff, Daryl Myers, Ibrahim Reda, Thomas Stoffel, Klaus Behrens, Thomas Carlund, Wolfgang Finsterle, and David Halliwell

Abstract

In the most comprehensive pyrheliometer comparison known to date, 33 instruments were deployed to measure direct normal solar radiation over a 10-month period in Golden, Colorado. The goal was to determine their performance relative to four electrical-substitution cavity radiometers that were calibrated against the World Radiometric Reference (WRR) that is maintained at the World Radiation Center in Davos, Switzerland. Because of intermittent cabling problems with one of the cavity radiometers, the average of three windowed, electrical-substitution cavity radiometers served as the reference irradiance for 29 test instruments during the 10-month study. To keep the size of this work manageable, comparisons are limited to stable sunny conditions, passing clouds, calm and windy conditions, and hot and cold temperatures. Other variables could have been analyzed, or the conditions analyzed could have employed higher resolution. A more complete study should be possible now that the instruments are identified; note that this analysis was performed without any knowledge on the part of the analyst of the instruments’ manufacturers or models. Apart from the windowed cavities that provided the best measurements, two categories of performance emerged during the comparison. All instruments exceeded expectations in that they measured with lower uncertainties than the manufacturers’ own specifications. Operational 95% uncertainties for the three classes of instruments, which include the uncertainties of the open cavities used for calibration, were about 0.5%, 0.8%, and 1.4%. The open cavities that were used for calibration of all pyrheliometers have an estimated 95% uncertainty of 0.4%–0.45%, which includes the conservative estimate of 0.3% uncertainty for the WRR.

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