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Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt
The purpose of this study is to validate the daily Terra-MODIS level 2 combined dark target (DT) and deep blue (DB) aerosol optical depth (AOD) retrievals with a spatial resolution of 10 km against the ground-based AERONET AOD data to be used in evaluating the air pollution and impact of meteorologi...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Springer International Publishing
2023
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10023315/ https://www.ncbi.nlm.nih.gov/pubmed/36932294 http://dx.doi.org/10.1007/s10661-023-11118-8 |
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author | Elshora, Mohamed |
author_facet | Elshora, Mohamed |
author_sort | Elshora, Mohamed |
collection | PubMed |
description | The purpose of this study is to validate the daily Terra-MODIS level 2 combined dark target (DT) and deep blue (DB) aerosol optical depth (AOD) retrievals with a spatial resolution of 10 km against the ground-based AERONET AOD data to be used in evaluating the air pollution and impact of meteorological variables over Qena, Egypt, in 2019. The regression analysis demonstrated an accepted agreement between the MODIS and AERONET AOD data with a correlation coefficient (R) of 0.7118 and 74.22% of the collocated points fall within the expected error (EE) limits. Quality flag filtering and spatial and temporal collocation were found to have a significant impact on the regression results. Quality flag filtering increased R by 0.2091 and % within EE by 17.97, spatial collocation increased R by 0.0143 and % within EE by 1.13, and temporal collocation increased R by 0.0089 and % within EE by 4.43. By validating the MODIS AOD data seasonally and analyzing the temporal distribution of the seasonal AOD data to show the retrieval accuracy variations between seasons, it was found that the MODIS AOD observations overestimated the AERONET AOD values in all seasons, and this may be because of underestimating the surface reflectance. Perhaps the main reason for the highest overestimation in summer and autumn is the transportation of aerosols from other regions, which changes the aerosol model in Qena, making accurate aerosol-type assumptions more difficult. Therefore, this study recommends necessary improvements regarding the aerosol model selection and the surface reflectance calculations. Temperature and relative humidity were found to have a strong negative relationship with a correlation of − 0.735, and both have a moderate association with AOD with a correlation of 0.451 and − 0.356, respectively. Because Qena is not a rainy city, precipitation was found to have no correlation with the other variables. |
format | Online Article Text |
id | pubmed-10023315 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | Springer International Publishing |
record_format | MEDLINE/PubMed |
spelling | pubmed-100233152023-03-19 Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt Elshora, Mohamed Environ Monit Assess Article The purpose of this study is to validate the daily Terra-MODIS level 2 combined dark target (DT) and deep blue (DB) aerosol optical depth (AOD) retrievals with a spatial resolution of 10 km against the ground-based AERONET AOD data to be used in evaluating the air pollution and impact of meteorological variables over Qena, Egypt, in 2019. The regression analysis demonstrated an accepted agreement between the MODIS and AERONET AOD data with a correlation coefficient (R) of 0.7118 and 74.22% of the collocated points fall within the expected error (EE) limits. Quality flag filtering and spatial and temporal collocation were found to have a significant impact on the regression results. Quality flag filtering increased R by 0.2091 and % within EE by 17.97, spatial collocation increased R by 0.0143 and % within EE by 1.13, and temporal collocation increased R by 0.0089 and % within EE by 4.43. By validating the MODIS AOD data seasonally and analyzing the temporal distribution of the seasonal AOD data to show the retrieval accuracy variations between seasons, it was found that the MODIS AOD observations overestimated the AERONET AOD values in all seasons, and this may be because of underestimating the surface reflectance. Perhaps the main reason for the highest overestimation in summer and autumn is the transportation of aerosols from other regions, which changes the aerosol model in Qena, making accurate aerosol-type assumptions more difficult. Therefore, this study recommends necessary improvements regarding the aerosol model selection and the surface reflectance calculations. Temperature and relative humidity were found to have a strong negative relationship with a correlation of − 0.735, and both have a moderate association with AOD with a correlation of 0.451 and − 0.356, respectively. Because Qena is not a rainy city, precipitation was found to have no correlation with the other variables. Springer International Publishing 2023-03-18 2023 /pmc/articles/PMC10023315/ /pubmed/36932294 http://dx.doi.org/10.1007/s10661-023-11118-8 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Article Elshora, Mohamed Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title | Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title_full | Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title_fullStr | Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title_full_unstemmed | Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title_short | Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt |
title_sort | evaluation of modis combined dt and db aod retrievals and their association with meteorological variables over qena, egypt |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10023315/ https://www.ncbi.nlm.nih.gov/pubmed/36932294 http://dx.doi.org/10.1007/s10661-023-11118-8 |
work_keys_str_mv | AT elshoramohamed evaluationofmodiscombineddtanddbaodretrievalsandtheirassociationwithmeteorologicalvariablesoverqenaegypt |