2023 |
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1. | V. E. Cachorro Revisiting basic sphere algorithms for Lorenz-Mie scattering under non-absorbing and absorbing media Conference ELX 2020, The 20th International Conference on Electromagnetic and Light Scattering Almuñecar, Spain, 2023. BibTeX | Tags: Light scattering, Radiative transfer @conference{Cachorro2023, |
2022 |
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2. | V. E. Cachorro; J. C. Antuña-Sanchez; Á. M. Frutos SSolar-GOA v1.0: a simple, fast, and accurate Spectral SOLAR radiative transfer model for clear skies Journal Article In: Geoscientific Model Development, vol. 15, no. 4, pp. 1689–1712, 2022. Abstract | Links | BibTeX | Tags: model, Radiative transfer, Solar radiation @article{Cachorro2022, 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. |
2021 |
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3. | 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. |
2020 |
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4. | Javier Vaquero-Martínez; Manuel Antón; Arturo Sanchez-Lorenzo; Victoria E Cachorro Evaluation of Water Vapor Radiative Effects Using GPS Data Series over Southwestern Europe Journal Article In: Remote Sensing, vol. 12, no. 8, 2020, ISSN: 2072-4292. Abstract | Links | BibTeX | Tags: Europe, long-wave, radiativa effect, Radiative transfer, Sourthwestern Europe, Spain, Water vapor @article{rs12081307, Water vapor radiative effects (WVRE) at surface in the long-wave (LW) and short-wave (SW) spectral ranges under cloud and aerosol free conditions are analyzed for seven stations in Spain over the 2007–2015 period. WVRE is calculated as the difference between the net flux obtained by two radiative transfer simulations; one with water vapor from Global Positioning System (GPS) measurements and the other one without any water vapor (dry atmosphere). The WVRE in the LW ranges from 107.9 Wm 2 to 296.7 Wm − 2 , while in the SW it goes from − 64.9 Wm − 2 to − 6.0 Wm − 2 . The results show a clear seasonal cycle, which allows the classification of stations in three sub-regions. In general, for total (SW + LW) and LW WVRE, winter (DJF) and spring (MAM) values are lower than summer (JJA) and autumn (SON). However, in the case of SW WVRE, the weaker values are in winter and autumn, and the stronger ones in summer and spring. Positive trends for LW (and total) WVRE may partially explain the well-known increase of surface air temperatures in the study region. Additionally, negative trends for SW WVRE are especially remarkable, since they represent about a quarter of the contribution of aerosols to the strong brightening effect (increase of the SW radiation flux at surface associated with a reduction of the cloud cover and aerosol load) observed since the 2000s in the Iberian Peninsula, but with opposite sign, so it is suggested that water vapor could be partially masking the full magnitude of this brightening. |
2011 |
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5. | Rosa Delia García Cabrera 2011, (Universidad de Valladolid. Dirección: Dra. Victoria Eugenia Cachorro y Dr. Emilio Cuevas Agulló.). Abstract | Links | BibTeX | Tags: Radiative transfer @phdthesis{Cabrera2011, En 1984 el Observatorio Atmosférico de Izaña se incorpora a la Red de Vigilancia de la Contaminación de Fondo (BAPMoN, Background Air Pollution Monitoring Network). En 1989 forma parte del programa de Vigilancia Atmosférica Global (VAG, GAW, Global Atmospheric Watch), y en 2009 la estación de Izaña es aceptada en la Red BSRN (Baseline Surface Radiation Network). Esta red es un proyecto del Observatorio de Radiación perteneciente al GEWEX (Global Energy and Water Cycle Experiment) en el marco del WCRP (World Climate Research Program). El objetivo de la BSRN es proporcionar observaciones de muy alta calidad, de radiación de onda corta y onda larga, con muy pequeños intervalos de muestreo (uno a tres minutos), con el fin de caracterizar la radiación solar a nivel mundial y detectar tendencias a largo plazo. En este trabajo de tesis doctoral abordamos el análisis de las tres componentes de la radiación solar (global, directa y difusa) medidas experimentalmente en la estación BSRN de Izaña. En primer lugar nos centraremos en la puesta a punto de las diferentes metodologías, algoritmos y técnicas de la BSRN, así como en la aplicación de los diferentes controles de calidad de las medidas. Uno de los objetivos principales de este trabajo es estudiar la capacidad y potencialidad del modelo de transferencia radiativa LibRadtran para simular la radiación solar, para su posterior aplicación en la implantación de controles de calidad, y en la reconstrucción de series temporales de radiación. Por este motivo, y como primer punto de partida, se ha llevado a cabo un estudio de sensibilidad del modelo para evaluar el comportamiento de la radiación simulada frente a variaciones de los principales parámetros atmosféricos. Posteriormente se ha realizado un estudio comparativo de las medidas experimentales frente a las simuladas en condiciones atmosféricas típicas en la estación de Izaña en días despejados durante 2009 y 2010. Asimismo se ha llevado a cabo una reconstrucción de la serie de radiación global en Izaña desde 1992, utilizando también registros de insolación. Una vez obtenida la serie temporal reconstruida de radiación global, se ha realizado un análisis de tendencia con la correspondiente valoración científica. Por último se ha llevado a cabo un análisis del forzamiento radiativo y de la eficiencia del forzamiento radiativo de los aerosoles atmosféricos en el espectro solar de la radiación global, directa y difusa en la estación BSRN de Izaña durante 2009 y 2010. Posteriormente se ha comparado con el forzamiento y la eficiencia facilitados por la Red AERONET (AErosol RObotic NETwork) para la radiación global a un ángulo cenital solar de 60°. Los algoritmos, técnicas y metodologías desarrolladas en este trabajo se podrían implementar en cualquier estación de medida radiométrica que quiera formar parte de la Red BSRN. |
Search an Article
2023 |
|
1. | Revisiting basic sphere algorithms for Lorenz-Mie scattering under non-absorbing and absorbing media Conference ELX 2020, The 20th International Conference on Electromagnetic and Light Scattering Almuñecar, Spain, 2023. |
2022 |
|
2. | SSolar-GOA v1.0: a simple, fast, and accurate Spectral SOLAR radiative transfer model for clear skies Journal Article In: Geoscientific Model Development, vol. 15, no. 4, pp. 1689–1712, 2022. |
2021 |
|
3. | Relative sky radiance from multi-exposure all-sky camera images Journal Article In: Atmospheric Measurement Techniques, vol. 14, no. 3, pp. 2201–2217, 2021. |
2020 |
|
4. | Evaluation of Water Vapor Radiative Effects Using GPS Data Series over Southwestern Europe Journal Article In: Remote Sensing, vol. 12, no. 8, 2020, ISSN: 2072-4292. |
2011 |
|
5. | 2011, (Universidad de Valladolid. Dirección: Dra. Victoria Eugenia Cachorro y Dr. Emilio Cuevas Agulló.). |