Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product
AERONET (AErosol RObotic NETwork), which is a network of ground-based sun photometers, produces a data product called the aerosol spectral deconvolution algorithm (SDA) that utilizes spectral total aerosol optical depth (AOD) data to infer the component fine- and coarse-mode optical depths at 500 nm...
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ftdoajarticles:oai:doaj.org/article:82a9c062828f40a1bc85b1b13473be84 2023-05-15T13:07:08+02:00 Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product A. Arola T. F. Eck H. Kokkola M. R. A. Pitkänen S. Romakkaniemi 2017-05-01T00:00:00Z https://doi.org/10.5194/acp-17-5991-2017 https://doaj.org/article/82a9c062828f40a1bc85b1b13473be84 EN eng Copernicus Publications http://www.atmos-chem-phys.net/17/5991/2017/acp-17-5991-2017.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 doi:10.5194/acp-17-5991-2017 https://doaj.org/article/82a9c062828f40a1bc85b1b13473be84 Atmospheric Chemistry and Physics, Vol 17, Iss 9, Pp 5991-6001 (2017) Physics QC1-999 Chemistry QD1-999 article 2017 ftdoajarticles https://doi.org/10.5194/acp-17-5991-2017 2022-12-31T04:19:13Z AERONET (AErosol RObotic NETwork), which is a network of ground-based sun photometers, produces a data product called the aerosol spectral deconvolution algorithm (SDA) that utilizes spectral total aerosol optical depth (AOD) data to infer the component fine- and coarse-mode optical depths at 500 nm. Based on its assumptions, SDA identifies cloud optical depth as the coarse-mode AOD component and therefore effectively computes the fine-mode AOD also in mixed cloud–aerosol observations. Therefore, it can be argued that the more representative AOD for fine-mode fraction should be based on all direct sun measurements and not only on those cloud screened for clear-sky conditions, i.e., on those from level 1 (L1) instead of level 2 (L2) in AERONET. The objective of our study was to assess, including all the available AERONET sites, how the fine-mode AOD is enhanced in cloudy conditions, contrasting SDA L1 and L2 in our analysis. Assuming that the cloud screening correctly separates the cloudy and clear-sky conditions, then the increases in fine-mode AOD can be due to various cloud-related processes, mainly by the strong hygroscopic growth of particles in the vicinity of clouds and in-cloud processing leading to growth of accumulation mode particles. We estimated these cloud-related enhancements in fine-mode AOD seasonally and found, for instance, that in June–August season the average over all the AERONET sites was 0.011, when total fine-mode AOD from L2 data was 0.154; therefore, the relative enhancement was 7 %. The enhancements were largest, both absolutely and relatively, in East Asia; for example, in June–August season the absolute and relative differences in fine-mode AOD, between L1 and L2 measurements, were 0.022 and 10 %, respectively. Corresponding values in North America and Europe were about 0.01 and 6–7 %. In some highly polluted areas, the enhancement is greater than these regional averages, e.g., in Beijing region and in June–July–August (JJA) season the corresponding absolute values were about 0.1. It ... Article in Journal/Newspaper Aerosol Robotic Network Directory of Open Access Journals: DOAJ Articles Atmospheric Chemistry and Physics 17 9 5991 6001 |
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Physics QC1-999 Chemistry QD1-999 |
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Physics QC1-999 Chemistry QD1-999 A. Arola T. F. Eck H. Kokkola M. R. A. Pitkänen S. Romakkaniemi Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
AERONET (AErosol RObotic NETwork), which is a network of ground-based sun photometers, produces a data product called the aerosol spectral deconvolution algorithm (SDA) that utilizes spectral total aerosol optical depth (AOD) data to infer the component fine- and coarse-mode optical depths at 500 nm. Based on its assumptions, SDA identifies cloud optical depth as the coarse-mode AOD component and therefore effectively computes the fine-mode AOD also in mixed cloud–aerosol observations. Therefore, it can be argued that the more representative AOD for fine-mode fraction should be based on all direct sun measurements and not only on those cloud screened for clear-sky conditions, i.e., on those from level 1 (L1) instead of level 2 (L2) in AERONET. The objective of our study was to assess, including all the available AERONET sites, how the fine-mode AOD is enhanced in cloudy conditions, contrasting SDA L1 and L2 in our analysis. Assuming that the cloud screening correctly separates the cloudy and clear-sky conditions, then the increases in fine-mode AOD can be due to various cloud-related processes, mainly by the strong hygroscopic growth of particles in the vicinity of clouds and in-cloud processing leading to growth of accumulation mode particles. We estimated these cloud-related enhancements in fine-mode AOD seasonally and found, for instance, that in June–August season the average over all the AERONET sites was 0.011, when total fine-mode AOD from L2 data was 0.154; therefore, the relative enhancement was 7 %. The enhancements were largest, both absolutely and relatively, in East Asia; for example, in June–August season the absolute and relative differences in fine-mode AOD, between L1 and L2 measurements, were 0.022 and 10 %, respectively. Corresponding values in North America and Europe were about 0.01 and 6–7 %. In some highly polluted areas, the enhancement is greater than these regional averages, e.g., in Beijing region and in June–July–August (JJA) season the corresponding absolute values were about 0.1. It ... |
format |
Article in Journal/Newspaper |
author |
A. Arola T. F. Eck H. Kokkola M. R. A. Pitkänen S. Romakkaniemi |
author_facet |
A. Arola T. F. Eck H. Kokkola M. R. A. Pitkänen S. Romakkaniemi |
author_sort |
A. Arola |
title |
Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
title_short |
Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
title_full |
Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
title_fullStr |
Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
title_full_unstemmed |
Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
title_sort |
assessment of cloud-related fine-mode aod enhancements based on aeronet sda product |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/acp-17-5991-2017 https://doaj.org/article/82a9c062828f40a1bc85b1b13473be84 |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_source |
Atmospheric Chemistry and Physics, Vol 17, Iss 9, Pp 5991-6001 (2017) |
op_relation |
http://www.atmos-chem-phys.net/17/5991/2017/acp-17-5991-2017.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 doi:10.5194/acp-17-5991-2017 https://doaj.org/article/82a9c062828f40a1bc85b1b13473be84 |
op_doi |
https://doi.org/10.5194/acp-17-5991-2017 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
17 |
container_issue |
9 |
container_start_page |
5991 |
op_container_end_page |
6001 |
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1766036242451922944 |