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Solar Spectral Measurements
Published in Frank Vignola, Joseph Michalsky, Thomas Stoffel, Solar and Infrared Radiation Measurements, 2019
Frank Vignola, Joseph Michalsky, Thomas Stoffel
Along these lines, the company Spectrafy™ (spectrafy.com) sells a sun photometer (SolarSIM-D2) and software that produces a spectral distribution of direct normal radiation (Tatsiankou et al. 2016). The sun photometer measures DNI at selected wavelengths to estimate the aerosol optical depth as a function of wavelength, water vapor column, and total column ozone amounts. These are the three main atmospheric variables that affect the amount of DNI at the surface. The other atmospheric constituents have fixed values that have much less effect on the DNI. These are input to the SMARTS model (Gueymard 2006) to produce a DNI spectrum at the SMARTS spectral resolution (0.5 nm between 280 and 400 nm, 1 nm between 400 and 1,700 nm, and 5 nm between 1,705 and 4,000 nm). Spectrafy™ also sells a spectral pyranometer (SolarSIM-G) that produces a spectral distribution of GHI from irradiance measurements at nine wavelengths and proprietary algorithms to generate solar spectra over the full 280–4,000 nm wavelength range (https://spectrafy.com/wp-content/uploads/2017/08/7th-Int.-Spectral-and-Broadband-Intercomparison-Spectrafy.pdf). A new rotating shadowband version of the SolarSIM-G called the SolarSIM-E is now available.
Remote Sensing Over Natural Water
Published in Robert P. Bukata, John H. Jerome, Kirill Ya. Kondratyev, Dimitry V. Pozdnyakov, of Inland and Coastal Waters, 2018
Robert P. Bukata, John H. Jerome, Kirill Ya. Kondratyev, Dimitry V. Pozdnyakov
Spanner et al.382 describe a technique for estimating aerosol optical depths using an airborne tracking sunphotometer to calculate total atmospheric optical depth from which is subtracted best-estimates of the optical depths due to Rayleigh scattering and absorption due to ozone and nitrogen dioxide. Mie theory is then used to estimate columnar aerosol densities, single-scattering albedo, and phase functions. The atmospheric optical properties so determined can then be utilized with radiative transfer models [Wrigley et al.431] to atmospherically correct Landsat Thematic Mapper data and high altitude C-130 aircraft data. Before proceeding with a discussion of some of the existing atmospheric correction models and/or techniques, we will briefly discuss radiative transfer models.
Properties of summer radiation and aerosols at Xinzhou, a suburban site on the North China Plain
Published in Atmospheric and Oceanic Science Letters, 2020
Jinqiang ZHANG, Jun ZHU, Xiang'ao XIA
Radiation and aerosols can greatly affect climate change and human and terrestrial environments (Pounds 2001; Anderson et al. 2003; Garrett and Zhao 2006). Both parameters are highly variable on temporal and spatial scales (e.g., Yang et al. 2016a; Fan, Zhao, and Yang 2020). Many approaches have been proposed for estimating radiation budgets, such as the surface measurements from the Baseline Surface Radiation Network (BSRN) of the World Climate Research Program, available since 1992 (Ohmura et al. 1998). This global network provides surface radiative flux data at the highest possible accuracy since its instrumentation is well calibrated and deployed at selected sites in the major climate zones. The BSRN measurements undergo rigorous quality checks to ensure high accuracy as well as homogeneity in the data (Wild et al. 2005). Aerosols have a vital impact on the Earth–atmosphere system through their direct and indirect radiative forcing (e.g., Xia et al. 2007; Zhao and Garrett 2015; Yang et al. 2016b). Several large ground-based sunphotometer networks—for example, the Aerosol Robotic Network (AERONET) (Holben et al. 1998), Photométrie pour le Traitement Opérationnel de Normalisation Satellitaire (PHOTONS) (Goloub et al. 2008), and the China Aerosol Remote Sensing Network (CARSNET) (Che et al. 2009)—have been established to characterize the aerosol optical properties that are widely used to validate satellite and model aerosol products.
The MACv2 aerosol climatology
Published in Tellus B: Chemical and Physical Meteorology, 2019
Solar attenuation measurements (simultaneously at different solar wavelengths by sun-photometry from the ground) offer at cloud-free conditions reliable data on aerosol amount and averages for aerosol size (distribution) and for aerosol absorption. Together these (three) aerosol properties even inform about aerosol compositional mixtures. Particular accurate are aerosol amount data, which are quantified by the aerosol optical depth (AOD). The AOD is the vertically normalized exponential decay coefficient of direct solar irradiance attributed to aerosol.