Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET
Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The p...
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ftdoajarticles:oai:doaj.org/article:0cf9945e9a594cafacebac1a7b560914 2023-05-15T13:07:10+02:00 Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET B. Torres C. Toledano A. Berjón D. Fuertes V. Molina R. Gonzalez M. Canini V. E. Cachorro P. Goloub T. Podvin L. Blarel O. Dubovik Y. Bennouna A. M. de Frutos 2013-08-01T00:00:00Z https://doi.org/10.5194/amt-6-2207-2013 https://doaj.org/article/0cf9945e9a594cafacebac1a7b560914 EN eng Copernicus Publications http://www.atmos-meas-tech.net/6/2207/2013/amt-6-2207-2013.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-6-2207-2013 1867-1381 1867-8548 https://doaj.org/article/0cf9945e9a594cafacebac1a7b560914 Atmospheric Measurement Techniques, Vol 6, Iss 8, Pp 2207-2220 (2013) Environmental engineering TA170-171 Earthwork. Foundations TA715-787 article 2013 ftdoajarticles https://doi.org/10.5194/amt-6-2207-2013 2022-12-31T01:28:10Z Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The present work relies on the analysis of two new measurement procedures (cross and matrix) specifically designed for the evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network (AERONET), the Cimel CE-318 Sun photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a Sun movement correction for an accurate evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show equivalent results with differences under 0.01° in the pointing error estimations. The second part of the analysis includes the incorporation of the cross procedure in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. The pointing error was evaluated using the data collected for more than a year, in 7 Sun photometers belonging to AERONET sites. The registered pointing error values were generally smaller than 0.1°, though in some instruments values up to 0.3° have been observed. Moreover, the pointing error analysis shows that this measurement can be useful to detect mechanical problems in the robots or dirtiness in the 4-quadrant detector used to track the Sun. Specifically, these mechanical faults can be detected due to the stable behavior of the values over time and vs. the solar zenith angle. Finally, the matrix procedure can be used to derive the value of the solid view angle of the instruments. The methodology has been implemented and applied for the characterization of 5 Sun photometers. To validate the method, a comparison with solid angles obtained from the vicarious calibration method was developed. The differences between both techniques are below 3%. Article in Journal/Newspaper Aerosol Robotic Network Directory of Open Access Journals: DOAJ Articles Atmospheric Measurement Techniques 6 8 2207 2220 |
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Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
spellingShingle |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 B. Torres C. Toledano A. Berjón D. Fuertes V. Molina R. Gonzalez M. Canini V. E. Cachorro P. Goloub T. Podvin L. Blarel O. Dubovik Y. Bennouna A. M. de Frutos Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
topic_facet |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
description |
Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The present work relies on the analysis of two new measurement procedures (cross and matrix) specifically designed for the evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network (AERONET), the Cimel CE-318 Sun photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a Sun movement correction for an accurate evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show equivalent results with differences under 0.01° in the pointing error estimations. The second part of the analysis includes the incorporation of the cross procedure in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. The pointing error was evaluated using the data collected for more than a year, in 7 Sun photometers belonging to AERONET sites. The registered pointing error values were generally smaller than 0.1°, though in some instruments values up to 0.3° have been observed. Moreover, the pointing error analysis shows that this measurement can be useful to detect mechanical problems in the robots or dirtiness in the 4-quadrant detector used to track the Sun. Specifically, these mechanical faults can be detected due to the stable behavior of the values over time and vs. the solar zenith angle. Finally, the matrix procedure can be used to derive the value of the solid view angle of the instruments. The methodology has been implemented and applied for the characterization of 5 Sun photometers. To validate the method, a comparison with solid angles obtained from the vicarious calibration method was developed. The differences between both techniques are below 3%. |
format |
Article in Journal/Newspaper |
author |
B. Torres C. Toledano A. Berjón D. Fuertes V. Molina R. Gonzalez M. Canini V. E. Cachorro P. Goloub T. Podvin L. Blarel O. Dubovik Y. Bennouna A. M. de Frutos |
author_facet |
B. Torres C. Toledano A. Berjón D. Fuertes V. Molina R. Gonzalez M. Canini V. E. Cachorro P. Goloub T. Podvin L. Blarel O. Dubovik Y. Bennouna A. M. de Frutos |
author_sort |
B. Torres |
title |
Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
title_short |
Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
title_full |
Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
title_fullStr |
Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
title_full_unstemmed |
Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET |
title_sort |
measurements on pointing error and field of view of cimel-318 sun photometers in the scope of aeronet |
publisher |
Copernicus Publications |
publishDate |
2013 |
url |
https://doi.org/10.5194/amt-6-2207-2013 https://doaj.org/article/0cf9945e9a594cafacebac1a7b560914 |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_source |
Atmospheric Measurement Techniques, Vol 6, Iss 8, Pp 2207-2220 (2013) |
op_relation |
http://www.atmos-meas-tech.net/6/2207/2013/amt-6-2207-2013.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-6-2207-2013 1867-1381 1867-8548 https://doaj.org/article/0cf9945e9a594cafacebac1a7b560914 |
op_doi |
https://doi.org/10.5194/amt-6-2207-2013 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
6 |
container_issue |
8 |
container_start_page |
2207 |
op_container_end_page |
2220 |
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1766038243948625920 |