Mission
The Atmospheric Optics Group of Valladolid University (GOA-UVa) is involved in the study of atmospheric components, mainly aerosols, with optical methods. The GOA calibration facility is devoted to radiometric calibration of optical instrumentations such as photometers, and it is part of the AERONET-Europe Central Facility, partially funded by the European Union.
As a university group, our researchers carry out educational and training activities (graduate, master and PhD thesis).
In this site you can find information about the work of the group, members, research lines, publications, projects, vacancies, etc.
Estos días se está llevando acabo en @AEMET_Izana una campaña para la caracterización espectral de la reflectancia lunar para mejorar el modelo de irradiancia lunar de la ESA (LIME, Lunar Irradiance Model of @ESA_es) junto con @goauva. Más información en https://t.co/o1zkkslQX2 pic.twitter.com/420PUVwn2a
— AEMET_Izaña (@AEMET_Izana) June 17, 2025
Latests 5 Publications
2025
1.
R. Román; D. González-Fernández; J. C. Antuña-Sánchez; C. Herrero del Barrio; S. Herrero-Anta; Á. Barreto; V. E. Cachorro; L. Doppler; R. González; C. Ritter; D. Mateos; N. Kouremeti; G. Copes; A. Calle; M. J. Granados-Muñoz; C. Toledano; Á. M. Frutos
Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime Journal Article
In: Atmospheric Measurement Techniques, vol. 18, no. 13, pp. 2847–2875, 2025.
@article{Román2025,
title = {Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime},
author = {R. Román and D. González-Fernández and J. C. Antuña-Sánchez and C. Herrero del Barrio and S. Herrero-Anta and Á. Barreto and V. E. Cachorro and L. Doppler and R. González and C. Ritter and D. Mateos and N. Kouremeti and G. Copes and A. Calle and M. J. Granados-Muñoz and C. Toledano and Á. M. Frutos},
url = {https://amt.copernicus.org/articles/18/2847/2025/},
doi = {10.5194/amt-18-2847-2025},
year = {2025},
date = {2025-07-04},
urldate = {2025-07-04},
journal = {Atmospheric Measurement Techniques},
volume = {18},
number = {13},
pages = {2847–2875},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2.
J. A. Añel; J. -C. Antuña-Marrero; A. Cid Samamed; C. Pérez-Souto; L. Torre; M. A. Valente; Y. Brugnara; A. Saiz-Lopez; L. Gimeno
Nineteenth- and twentieth-century semi-quantitative surface ozone along subtropical European to tropical Africa Atlantic coasts Journal Article
In: Earth System Science Data, vol. 17, no. 6, pp. 2437–2446, 2025.
@article{Añel2025b,
title = {Nineteenth- and twentieth-century semi-quantitative surface ozone along subtropical European to tropical Africa Atlantic coasts},
author = {J. A. Añel and J. -C. Antuña-Marrero and A. Cid Samamed and C. Pérez-Souto and L. Torre and M. A. Valente and Y. Brugnara and A. Saiz-Lopez and L. Gimeno},
url = {https://essd.copernicus.org/articles/17/2437/2025/},
doi = {10.5194/essd-17-2437-2025},
year = {2025},
date = {2025-06-06},
urldate = {2025-01-01},
journal = {Earth System Science Data},
volume = {17},
number = {6},
pages = {2437–2446},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
3.
Niklas Blum; Paul Matteschk; Yann Fabel; Bijan Nouri; Roberto Román; Luis F. Zarzalejo; Juan Carlos Antuña-Sánchez; Stefan Wilbert
Geometric calibration of all-sky cameras using sun and moon positions: A comprehensive analysis Journal Article
In: Solar Energy, vol. 295, pp. 113476, 2025, ISSN: 0038-092X.
@article{BLUM2025113476,
title = {Geometric calibration of all-sky cameras using sun and moon positions: A comprehensive analysis},
author = {Niklas Blum and Paul Matteschk and Yann Fabel and Bijan Nouri and Roberto Román and Luis F. Zarzalejo and Juan Carlos Antuña-Sánchez and Stefan Wilbert},
url = {https://www.sciencedirect.com/science/article/pii/S0038092X25002397},
doi = {https://doi.org/10.1016/j.solener.2025.113476},
issn = {0038-092X},
year = {2025},
date = {2025-03-24},
urldate = {2025-01-01},
journal = {Solar Energy},
volume = {295},
pages = {113476},
abstract = {All-sky imagers (ASIs) have been applied to enable accurate very-short-term forecasts of the production of solar power plants and to derive measurements which facilitate the efficient and reliable operation of such plants. Overall, ASIs can support the grid integration and efficient operation of solar power plants. These tasks often require to reconstruct ‘world coordinates’ of observed scene points from their position in the ASI images. This requires a practically feasible geometric calibration of each ASI regarding camera-intrinsic lens distortion parameters and the ASI’s external orientation. We present ‘SuMo’ an open-source Python tool which determines all relevant parameters only using regular ASI images of Sun and Moon. The method avoids a manual interference on-site, can be applied retrospectively and can also be used to continuously monitor an ASI’s geometric calibration. We validate the calibration method on five cameras at three sites and over various datasets representing different seasons, atmospheric conditions, exposure times and sun/ moon elevation and azimuth angles. Already a single month of images from either summer or winter yields an accurate calibration (RMSE ?0.14?). A comparable calibration accuracy (RMSE 0.14 – 0.38?) could be achieved for all tested ASIs without modifying any of the method’s parameters. Image quality moderately influenced the calibration accuracy. An additional cross-validation with the star-based ORION calibration method further confirms the high accuracy of our method over the entire sky dome (MAE 0.14?). We provide a Python package and >2 years of ASI images and irradiance measurements with the publication.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
All-sky imagers (ASIs) have been applied to enable accurate very-short-term forecasts of the production of solar power plants and to derive measurements which facilitate the efficient and reliable operation of such plants. Overall, ASIs can support the grid integration and efficient operation of solar power plants. These tasks often require to reconstruct ‘world coordinates’ of observed scene points from their position in the ASI images. This requires a practically feasible geometric calibration of each ASI regarding camera-intrinsic lens distortion parameters and the ASI’s external orientation. We present ‘SuMo’ an open-source Python tool which determines all relevant parameters only using regular ASI images of Sun and Moon. The method avoids a manual interference on-site, can be applied retrospectively and can also be used to continuously monitor an ASI’s geometric calibration. We validate the calibration method on five cameras at three sites and over various datasets representing different seasons, atmospheric conditions, exposure times and sun/ moon elevation and azimuth angles. Already a single month of images from either summer or winter yields an accurate calibration (RMSE ?0.14?). A comparable calibration accuracy (RMSE 0.14 – 0.38?) could be achieved for all tested ASIs without modifying any of the method’s parameters. Image quality moderately influenced the calibration accuracy. An additional cross-validation with the star-based ORION calibration method further confirms the high accuracy of our method over the entire sky dome (MAE 0.14?). We provide a Python package and >2 years of ASI images and irradiance measurements with the publication.
4.
J. C. Antuña-Marrero; R. Román; V. E. Cachorro; D. Mateos; C. Toledano; A. Calle; J. C. Antuña-Sánchez; R. Gonzalez; M. Antón; J. Vaquero-Martínez; Á. M. Frutos Baraja
Comparing Integrated Water Vapor Sun Photometer Observations Over the Arctic With ERA5 and MERRA-2 Reanalyses Journal Article
In: Journal of Geophysical Research: Atmospheres, vol. 130, no. 6, pp. e2024JD041120, 2025, (e2024JD041120 2024JD041120).
@article{Antuña-Marrero2025b,
title = {Comparing Integrated Water Vapor Sun Photometer Observations Over the Arctic With ERA5 and MERRA-2 Reanalyses},
author = {J. C. Antuña-Marrero and R. Román and V. E. Cachorro and D. Mateos and C. Toledano and A. Calle and J. C. Antuña-Sánchez and R. Gonzalez and M. Antón and J. Vaquero-Martínez and Á. M. Frutos Baraja},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2024JD041120},
doi = {https://doi.org/10.1029/2024JD041120},
year = {2025},
date = {2025-03-17},
urldate = {2025-01-01},
journal = {Journal of Geophysical Research: Atmospheres},
volume = {130},
number = {6},
pages = {e2024JD041120},
abstract = {Abstract Atmospheric water vapor, a greenhouse gas, is increasing in the Arctic. It is a scientific challenge to understand the causes for this increase and determine adaptation and mitigation actions to confront its climatic effects. During the last decades, spatial and temporal coverage of water vapor satellite observations increased notably, and reanalysis water vapor estimates have steadily improved. However, the scarce spatial and temporal coverage in the Arctic of integrated water vapor (IWV) surface-based observations limits the representativeness of satellite observations and reanalysis estimate validations. Recently, we validated sun photometer IWV (IWVsp) observations with IWV from radiosondes in the Arctic. Here, we compare the hourly means of IWVsp from 13 Arctic AERONET stations and the IWV from ERA-5 and MERRA-2 reanalyses. The comparison is conducted at hourly timescale for individual stations for two Arctic regions and for the whole Arctic. The comparison showed a moist bias of IWV from reanalyses with respect to IWVsp. The individual station wise pattern shows slightly better accuracy and precision for ERA5 than for MERRA-2 also evident at the selected subregional scale. The differences of IWV from ERA5 and MERRA-2 and IWVsp show no dependence on IWVsp nor the solar zenith angle. This study corroborates that IWVsp may be used for validations of satellite IWV observations and IWV reanalyses products.},
note = {e2024JD041120 2024JD041120},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Atmospheric water vapor, a greenhouse gas, is increasing in the Arctic. It is a scientific challenge to understand the causes for this increase and determine adaptation and mitigation actions to confront its climatic effects. During the last decades, spatial and temporal coverage of water vapor satellite observations increased notably, and reanalysis water vapor estimates have steadily improved. However, the scarce spatial and temporal coverage in the Arctic of integrated water vapor (IWV) surface-based observations limits the representativeness of satellite observations and reanalysis estimate validations. Recently, we validated sun photometer IWV (IWVsp) observations with IWV from radiosondes in the Arctic. Here, we compare the hourly means of IWVsp from 13 Arctic AERONET stations and the IWV from ERA-5 and MERRA-2 reanalyses. The comparison is conducted at hourly timescale for individual stations for two Arctic regions and for the whole Arctic. The comparison showed a moist bias of IWV from reanalyses with respect to IWVsp. The individual station wise pattern shows slightly better accuracy and precision for ERA5 than for MERRA-2 also evident at the selected subregional scale. The differences of IWV from ERA5 and MERRA-2 and IWVsp show no dependence on IWVsp nor the solar zenith angle. This study corroborates that IWVsp may be used for validations of satellite IWV observations and IWV reanalyses products.
5.
Juan A. Añel; Ingrid Cnossen; Juan Carlos Antuña-Marrero; Gufran Beig; Matthew K. Brown; Eelco Doornbos; Scott Osprey; Shaylah Maria Mutschler; Celia Pérez Souto; Petr Šácha; Viktoria Sofieva; Laura de la Torre; Shun-Rong Zhang; Martin G. Mlynczak
The Need for Better Monitoring of Climate Change in the Middle and Upper Atmosphere Journal Article
In: AGU Advances, vol. 6, no. 2, pp. e2024AV001465, 2025, (e2024AV001465 2024AV001465).
@article{Añel2025,
title = {The Need for Better Monitoring of Climate Change in the Middle and Upper Atmosphere},
author = {Juan A. Añel and Ingrid Cnossen and Juan Carlos Antuña-Marrero and Gufran Beig and Matthew K. Brown and Eelco Doornbos and Scott Osprey and Shaylah Maria Mutschler and Celia Pérez Souto and Petr Šácha and Viktoria Sofieva and Laura de la Torre and Shun-Rong Zhang and Martin G. Mlynczak},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2024AV001465},
doi = {https://doi.org/10.1029/2024AV001465},
year = {2025},
date = {2025-02-28},
urldate = {2025-01-01},
journal = {AGU Advances},
volume = {6},
number = {2},
pages = {e2024AV001465},
abstract = {Abstract Anthropogenic greenhouse gas emissions significantly impact the middle and upper atmosphere. They cause cooling and thermal shrinking and affect the atmospheric structure. Atmospheric contraction results in changes in key atmospheric features, such as the stratopause height or the peak ionospheric electron density, and also results in reduced thermosphere density. These changes can impact, among others, the lifespan of objects in low Earth orbit, refraction of radio communication and GPS signals, and the peak altitudes of meteoroids entering the Earth's atmosphere. Given this, there is a critical need for observational capabilities to monitor the middle and upper atmosphere. Equally important is the commitment to maintaining and improving long-term, homogeneous data collection. However, capabilities to observe the middle and upper atmosphere are decreasing rather than improving.},
note = {e2024AV001465 2024AV001465},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Anthropogenic greenhouse gas emissions significantly impact the middle and upper atmosphere. They cause cooling and thermal shrinking and affect the atmospheric structure. Atmospheric contraction results in changes in key atmospheric features, such as the stratopause height or the peak ionospheric electron density, and also results in reduced thermosphere density. These changes can impact, among others, the lifespan of objects in low Earth orbit, refraction of radio communication and GPS signals, and the peak altitudes of meteoroids entering the Earth's atmosphere. Given this, there is a critical need for observational capabilities to monitor the middle and upper atmosphere. Equally important is the commitment to maintaining and improving long-term, homogeneous data collection. However, capabilities to observe the middle and upper atmosphere are decreasing rather than improving.