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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ftuniveasternfin:oai:erepo.uef.fi:123456789/4941 2023-05-15T13:07:07+02:00 Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product Arola Antti Eck Thomas F Kokkola Harri Pitkänen Mikko R A Romakkaniemi Sami Department of Applied Physics, activities 2017-11-22T10:58:58Z 5991-6001 https://erepo.uef.fi/handle/123456789/4941 EN eng Copernicus GmbH ATMOSPHERIC CHEMISTRY AND PHYSICS http://dx.doi.org/10.5194/acp-17-5991-2017 10.5194/acp-17-5991-2017 1680-7316 9 17 https://erepo.uef.fi/handle/123456789/4941 CC BY 3.0 openAccess © Authors https://creativecommons.org/licenses/by/3.0/ CC-BY info:eu-repo/semantics/article A1 info:eu-repo/semantics/publishedVersion article artikkeli 2017 ftuniveasternfin https://doi.org/10.5194/acp-17-5991-2017 2023-01-25T23:58:20Z 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 UEF eRepository (University of Eastern Finland) Atmospheric Chemistry and Physics 17 9 5991 6001 |
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UEF eRepository (University of Eastern Finland) |
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ftuniveasternfin |
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English |
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 ... |
author2 |
Department of Applied Physics, activities |
format |
Article in Journal/Newspaper |
author |
Arola Antti Eck Thomas F Kokkola Harri Pitkänen Mikko R A Romakkaniemi Sami |
spellingShingle |
Arola Antti Eck Thomas F Kokkola Harri Pitkänen Mikko R A Romakkaniemi Sami Assessment of cloud-related fine-mode AOD enhancements based on AERONET SDA product |
author_facet |
Arola Antti Eck Thomas F Kokkola Harri Pitkänen Mikko R A Romakkaniemi Sami |
author_sort |
Arola Antti |
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 GmbH |
publishDate |
2017 |
url |
https://erepo.uef.fi/handle/123456789/4941 |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_relation |
ATMOSPHERIC CHEMISTRY AND PHYSICS http://dx.doi.org/10.5194/acp-17-5991-2017 10.5194/acp-17-5991-2017 1680-7316 9 17 https://erepo.uef.fi/handle/123456789/4941 |
op_rights |
CC BY 3.0 openAccess © Authors https://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
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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1766036109800767488 |