2023 |
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1. | S. Herrero-Anta; R. Román; D. Mateos; R. González; J. C. Antuña-Sánchez; M. Herreras-Giralda; A. F. Almansa; D. González-Fernández; C. Herrero del Barrio; C. Toledano; V. E. Cachorro; Á. M. Frutos Retrieval of aerosol properties from zenith sky radiance measurements Conference European Aerosol Conference 2023, Málaga, Spain, 2023. BibTeX | Tags: aerosol inversion, AOD, GRASP, sky radiance @conference{Herrero-Anta2023c, |
2. | S. Herrero-Anta; R. Román, D. Mateos, J.C. Antuña-Sánchez, C. Toledano, F. Almansa, R. González, M. Herreras-Giralda, D. González-Fernández, C. Herrero del Barrio, V.E. Cachorro; A.M. de Frutos Retrieval of aerosol properties from zenith sky radiance measurements Conference Workshop on “Recent advancements in remote sensing and modeling of aerosols, clouds and surfaces” GRASP ACE Summer school, Lille, France, 2023. BibTeX | Tags: aerosol inversion, AOD, GRASP, sky radiance @conference{Herrero-Anta2023b, |
2022 |
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3. | R. Román; D. González-Fernández; C. Toledano; C. Emde; V. Cachorro; D. Mateos; S. Herrero-Anta; J. C. Antuña-Sánchez; R. González; J.C. Antuña-Marrero; B. Mayer; A. Calle; A.M. de Frutos Impact of clouds on cloud-free sky radiances in a partially cloudy scenario Conference International Radiation Symposium Thessaloniki, Greece, 2022. BibTeX | Tags: all-sky camera, clouds, GRASP, sky radiance @conference{Román2022b, |
4. | Juan Carlos Antuña Sánchez Universidad de Valladolid, 2022, (dirección: Roberto Román, Ángel M. de Frutos y Victoria E. Cachorro.). Abstract | Links | BibTeX | Tags: all-sky camera, atmospheric aerosols, sky radiance @phdthesis{Sánchez2021, Atmospheric aerosols, solid or liquid particles floating in the atmosphere, play an important role in the Earth's climate, since they scatter and absorb part of the solar radiation reaching the Earth. The aerosol properties are usually obtained by measuring the diffuse solar radiation incoming in different directions (sky radiance), which is partially formed by the scattering of aerosols. The sky radiance is usually measured with photometers. A cheaper alternative to these photometers are the all-sky cameras, which capture images of the whole sky. In this doctoral thesis we propose the use of all-sky cameras to retrieve atmospheric parameters like the sky radiance and some aerosol properties, which can be obtained from these radiances. In this work, the ORION application has been developed to calibrate geometrically the all-sky cameras through the position of the stars. These calibrations are essential to locate the pixels of the camera pointing to a specific direction, such as the directions in which the sky radiance will be extracted. An all-sky camera has been geometrically calibrated with ORION, but it also has been configured to capture images in RAW format at different exposure times. The multi-exposure configuration, in addition with a exhaustive characterization of the camera (effective wavelengths, linearity, read noise, etc.), has allowed to obtain a linear high dynamic range image of the sky applying a proposed methodology. The sky radiance is proportional to the linear image obtained, so a relative sky radiance can be obtained with this proposed methodology. Once the relative sky radiances have been obtained with the all-sky camera, they have been used as input parameter in the GRASP (Generalized Retrieval of Atmosphere and Surface Properties) inversion algorithm to obtain some aerosol properties. It has been studied, using synthetic data, what aerosol properties can be derived from the relative sky radiance measured by all-sky cameras. The aerosol properties obtained with real measurements on GRASP have been compared with those independently derived by an AERONET (AErosol RObotic NETwork) photometer. This work concludes that, if the methodologies developed in this doctoral thesis are applied, a properly configured all-sky camera can be used to calculate the sky radiance, at least in a relative way, and these radiances can be also used to retrieve aerosol properties. |
2021 |
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5. | J C Antuña-Sánchez; R Román; V E Cachorro; C Toledano; C López; R González; D Mateos; A Calle; Á M de Frutos Relative sky radiance from multi-exposure all-sky camera images Journal Article In: Atmospheric Measurement Techniques, vol. 14, no. 3, pp. 2201–2217, 2021. Abstract | Links | BibTeX | Tags: Radiative transfer, sky camera, sky radiance @article{amt-14-2201-2021, All-sky cameras are frequently used to detect cloud cover; however, this work explores the use of these instruments for the more complex purpose of extracting relative sky radiances. An all-sky camera (SONA202-NF model) with three colour filters narrower than usual for this kind of cameras is configured to capture raw images at seven exposure times. A detailed camera characterization of the black level, readout noise, hot pixels and linear response is carried out. A methodology is proposed to obtain a linear high dynamic range (HDR) image and its uncertainty, which represents the relative sky radiance (in arbitrary units) maps at three effective wavelengths. The relative sky radiances are extracted from these maps and normalized by dividing every radiance of one channel by the sum of all radiances at this channel. Then, the normalized radiances are compared with the sky radiance measured at different sky points by a sun and sky photometer belonging to the Aerosol Robotic Network (AERONET). The camera radiances correlate with photometer ones except for scattering angles below 10?, which is probably due to some light reflections on the fisheye lens and camera dome. Camera and photometer wavelengths are not coincident; hence, camera radiances are also compared with sky radiances simulated by a radiative transfer model at the same camera effective wavelengths. This comparison reveals an uncertainty on the normalized camera radiances of about 3.3?%, 4.3?% and 5.3?% for 467, 536 and 605?nm, respectively, if specific quality criteria are applied. |
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2023 |
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1. | Retrieval of aerosol properties from zenith sky radiance measurements Conference European Aerosol Conference 2023, Málaga, Spain, 2023. |
2. | Retrieval of aerosol properties from zenith sky radiance measurements Conference Workshop on “Recent advancements in remote sensing and modeling of aerosols, clouds and surfaces” GRASP ACE Summer school, Lille, France, 2023. |
2022 |
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3. | Impact of clouds on cloud-free sky radiances in a partially cloudy scenario Conference International Radiation Symposium Thessaloniki, Greece, 2022. |
4. | Universidad de Valladolid, 2022, (dirección: Roberto Román, Ángel M. de Frutos y Victoria E. Cachorro.). |
2021 |
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5. | Relative sky radiance from multi-exposure all-sky camera images Journal Article In: Atmospheric Measurement Techniques, vol. 14, no. 3, pp. 2201–2217, 2021. |