Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime
<p>The lack of aerosol optical depth (AOD) data at night can be partially addressed through Moon photometer measurements or fully covered with star photometer observations. However, the limited availability and complexity of star photometers have motivated this study to use all-sky cameras to...
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
|
| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/18/2847/2025/amt-18-2847-2025.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849425458821595136 |
|---|---|
| author | R. Román R. Román D. González-Fernández D. González-Fernández J. C. Antuña-Sánchez J. C. Antuña-Sánchez C. Herrero del Barrio C. Herrero del Barrio S. Herrero-Anta S. Herrero-Anta Á. Barreto Á. Barreto V. E. Cachorro V. E. Cachorro L. Doppler R. González R. González C. Ritter C. Ritter D. Mateos D. Mateos N. Kouremeti G. Copes A. Calle A. Calle M. J. Granados-Muñoz M. J. Granados-Muñoz C. Toledano C. Toledano Á. M. de Frutos Á. M. de Frutos |
| author_facet | R. Román R. Román D. González-Fernández D. González-Fernández J. C. Antuña-Sánchez J. C. Antuña-Sánchez C. Herrero del Barrio C. Herrero del Barrio S. Herrero-Anta S. Herrero-Anta Á. Barreto Á. Barreto V. E. Cachorro V. E. Cachorro L. Doppler R. González R. González C. Ritter C. Ritter D. Mateos D. Mateos N. Kouremeti G. Copes A. Calle A. Calle M. J. Granados-Muñoz M. J. Granados-Muñoz C. Toledano C. Toledano Á. M. de Frutos Á. M. de Frutos |
| author_sort | R. Román |
| collection | DOAJ |
| description | <p>The lack of aerosol optical depth (AOD) data at night can be partially addressed through Moon photometer measurements or fully covered with star photometer observations. However, the limited availability and complexity of star photometers have motivated this study to use all-sky cameras to extract starlight signals and derive AOD at night using star photometry. For this purpose, eight all-sky cameras were configured and deployed in nine different locations to capture raw images with varying exposure times every 2 min during the night. This work proposes a novel methodology to extract the starlight signal from the raw data from all-sky cameras and convert it into AOD values. This process consists of the following steps: removing the background image, selecting the pixels, and extracting the signal for each star from a predefined list of 56 stars; performing in situ Langley calibration of the instruments and retrieving the total optical depth (TOD); calculating the effective wavelength for each camera channel; deriving the AOD by subtracting the gas contribution to TOD; and averaging, cloud-screening, and quality-assuring the AOD time series. The AOD time series obtained through this methodology are compared with independent AOD measurements from collocated Moon photometers in the nine locations. The obtained results show that the AOD values derived with the proposed method generally correlate with reference values, often achieving correlation coefficients (<span class="inline-formula"><i>r</i></span>) above 0.90. The AOD values retrieved using the cameras tend to overestimate the reference values by approximately 0.02 and exhibit a precision of around 0.03–0.04. The agreement between the two datasets varies with wavelength and decreases at high-latitude locations, likely due to the poorer performance of Langley calibration in these regions. AOD values align well with day-to-night transitions obtained by solar photometers, demonstrating their reliability. Despite the slight overestimation, the AOD values derived by this new method approximate the real values and provide coverage throughout the entire night, without requiring the presence of the Moon. Therefore, they serve to study and monitor the nocturnal evolution of AOD.</p> |
| format | Article |
| id | doaj-art-9b9ccf35f90b4c6bb6bef53710a734c3 |
| institution | Kabale University |
| issn | 1867-1381 1867-8548 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj-art-9b9ccf35f90b4c6bb6bef53710a734c32025-08-20T03:29:45ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482025-07-01182847287510.5194/amt-18-2847-2025Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttimeR. Román0R. Román1D. González-Fernández2D. González-Fernández3J. C. Antuña-Sánchez4J. C. Antuña-Sánchez5C. Herrero del Barrio6C. Herrero del Barrio7S. Herrero-Anta8S. Herrero-Anta9Á. Barreto10Á. Barreto11V. E. Cachorro12V. E. Cachorro13L. Doppler14R. González15R. González16C. Ritter17C. Ritter18D. Mateos19D. Mateos20N. Kouremeti21G. Copes22A. Calle23A. Calle24M. J. Granados-Muñoz25M. J. Granados-Muñoz26C. Toledano27C. Toledano28Á. M. de Frutos29Á. M. de Frutos30Group of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainGRASP-SAS, 59000, Lille, FranceGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainIzaña Atmospheric Research Center, Meteorological State Agency of Spain (AEMet), 38001, Santa Cruz de Tenerife, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainDeutscher Wetterdienst, Meteorologisches Observatorium Lindenberg – Richard-Aßmann-Observatorium (DWD, MOL-RAO), 15848 Lindenberg (Tauche), GermanyGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainInstitute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, GermanyAlfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, GermanyGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainPhysikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), 7260 Davos, SwitzerlandServicio Meteorológico Nacional, 4019, Buenos Aires, ArgentinaGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainDepartment of Applied Physics, Universidad de Granada, 18071, Granada, SpainAndalusian Institute for Earth System Research, IISTA-CEAMA, 18006, Granada, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, SpainGroup of Atmospheric Optics (GOA-UVa), Universidad de Valladolid, 47011, Valladolid, SpainLaboratory of Disruptive Interdisciplinary Science (LaDIS), 47011, Valladolid, Spain<p>The lack of aerosol optical depth (AOD) data at night can be partially addressed through Moon photometer measurements or fully covered with star photometer observations. However, the limited availability and complexity of star photometers have motivated this study to use all-sky cameras to extract starlight signals and derive AOD at night using star photometry. For this purpose, eight all-sky cameras were configured and deployed in nine different locations to capture raw images with varying exposure times every 2 min during the night. This work proposes a novel methodology to extract the starlight signal from the raw data from all-sky cameras and convert it into AOD values. This process consists of the following steps: removing the background image, selecting the pixels, and extracting the signal for each star from a predefined list of 56 stars; performing in situ Langley calibration of the instruments and retrieving the total optical depth (TOD); calculating the effective wavelength for each camera channel; deriving the AOD by subtracting the gas contribution to TOD; and averaging, cloud-screening, and quality-assuring the AOD time series. The AOD time series obtained through this methodology are compared with independent AOD measurements from collocated Moon photometers in the nine locations. The obtained results show that the AOD values derived with the proposed method generally correlate with reference values, often achieving correlation coefficients (<span class="inline-formula"><i>r</i></span>) above 0.90. The AOD values retrieved using the cameras tend to overestimate the reference values by approximately 0.02 and exhibit a precision of around 0.03–0.04. The agreement between the two datasets varies with wavelength and decreases at high-latitude locations, likely due to the poorer performance of Langley calibration in these regions. AOD values align well with day-to-night transitions obtained by solar photometers, demonstrating their reliability. Despite the slight overestimation, the AOD values derived by this new method approximate the real values and provide coverage throughout the entire night, without requiring the presence of the Moon. Therefore, they serve to study and monitor the nocturnal evolution of AOD.</p>https://amt.copernicus.org/articles/18/2847/2025/amt-18-2847-2025.pdf |
| spellingShingle | R. Román R. Román D. González-Fernández D. González-Fernández J. C. Antuña-Sánchez J. C. Antuña-Sánchez C. Herrero del Barrio C. Herrero del Barrio S. Herrero-Anta S. Herrero-Anta Á. Barreto Á. Barreto V. E. Cachorro V. E. Cachorro L. Doppler R. González R. González C. Ritter C. Ritter D. Mateos D. Mateos N. Kouremeti G. Copes A. Calle A. Calle M. J. Granados-Muñoz M. J. Granados-Muñoz C. Toledano C. Toledano Á. M. de Frutos Á. M. de Frutos Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime Atmospheric Measurement Techniques |
| title | Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime |
| title_full | Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime |
| title_fullStr | Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime |
| title_full_unstemmed | Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime |
| title_short | Star photometry with all-sky cameras to retrieve aerosol optical depth at nighttime |
| title_sort | star photometry with all sky cameras to retrieve aerosol optical depth at nighttime |
| url | https://amt.copernicus.org/articles/18/2847/2025/amt-18-2847-2025.pdf |
| work_keys_str_mv | AT rroman starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT rroman starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT dgonzalezfernandez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT dgonzalezfernandez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT jcantunasanchez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT jcantunasanchez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT cherrerodelbarrio starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT cherrerodelbarrio starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT sherreroanta starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT sherreroanta starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT abarreto starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT abarreto starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT vecachorro starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT vecachorro starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT ldoppler starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT rgonzalez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT rgonzalez starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT critter starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT critter starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT dmateos starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT dmateos starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT nkouremeti starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT gcopes starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT acalle starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT acalle starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT mjgranadosmunoz starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT mjgranadosmunoz starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT ctoledano starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT ctoledano starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT amdefrutos starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime AT amdefrutos starphotometrywithallskycamerastoretrieveaerosolopticaldepthatnighttime |