Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories
Even though the Arctic is remote, aerosol properties observed there are strongly influenced by anthropogenic emissions from outside the Arctic. This is particularly true for the so-called Arctic haze season (January through April). In summer (June through September), when atmospheric transport patte...
Published in: | Atmospheric Chemistry and Physics |
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2022
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Online Access: | https://doi.org/10.5194/acp-22-3067-2022 https://acp.copernicus.org/articles/22/3067/2022/ |
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English |
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Even though the Arctic is remote, aerosol properties observed there are strongly influenced by anthropogenic emissions from outside the Arctic. This is particularly true for the so-called Arctic haze season (January through April). In summer (June through September), when atmospheric transport patterns change, and precipitation is more frequent, local Arctic sources, i.e., natural sources of aerosols and precursors, play an important role. Over the last few decades, significant reductions in anthropogenic emissions have taken place. At the same time a large body of literature shows evidence that the Arctic is undergoing fundamental environmental changes due to climate forcing, leading to enhanced emissions by natural processes that may impact aerosol properties. In this study, we analyze 9 aerosol chemical species and 4 particle optical properties from 10 Arctic observatories (Alert, Kevo, Pallas, Summit, Thule, Tiksi, Barrow/Utqiaġvik, Villum, and Gruvebadet and Zeppelin Observatory – both at Ny-Ålesund Research Station) to understand changes in anthropogenic and natural aerosol contributions. Variables include equivalent black carbon, particulate sulfate, nitrate, ammonium, methanesulfonic acid, sodium, iron, calcium and potassium, as well as scattering and absorption coefficients, single scattering albedo and scattering Ångström exponent. First, annual cycles are investigated, which despite anthropogenic emission reductions still show the Arctic haze phenomenon. Second, long-term trends are studied using the Mann–Kendall Theil–Sen slope method. We find in total 41 significant trends over full station records, i.e., spanning more than a decade, compared to 26 significant decadal trends. The majority of significantly declining trends is from anthropogenic tracers and occurred during the haze period, driven by emission changes between 1990 and 2000. For the summer period, no uniform picture of trends has emerged. Twenty-six percent of trends, i.e., 19 out of 73, are significant, and of those 5 are positive and 14 are negative. Negative trends include not only anthropogenic tracers such as equivalent black carbon at Kevo, but also natural indicators such as methanesulfonic acid and non-sea-salt calcium at Alert. Positive trends are observed for sulfate at Gruvebadet. No clear evidence of a significant change in the natural aerosol contribution can be observed yet. However, testing the sensitivity of the Mann–Kendall Theil–Sen method, we find that monotonic changes of around 5 % yr −1 in an aerosol property are needed to detect a significant trend within one decade. This highlights that long-term efforts well beyond a decade are needed to capture smaller changes. It is particularly important to understand the ongoing natural changes in the Arctic, where interannual variability can be high, such as with forest fire emissions and their influence on the aerosol population. To investigate the climate-change-induced influence on the aerosol population and the resulting climate feedback, long-term observations of tracers more specific to natural sources are needed, as well as of particle microphysical properties such as size distributions, which can be used to identify changes in particle populations which are not well captured by mass-oriented methods such as bulk chemical composition. |
format |
Text |
author |
Schmale, Julia Sharma, Sangeeta Decesari, Stefano Pernov, Jakob Massling, Andreas Hansson, Hans-Christen Salzen, Knut Skov, Henrik Andrews, Elisabeth Quinn, Patricia K. Upchurch, Lucia M. Eleftheriadis, Konstantinos Traversi, Rita Gilardoni, Stefania Mazzola, Mauro Laing, James Hopke, Philip |
spellingShingle |
Schmale, Julia Sharma, Sangeeta Decesari, Stefano Pernov, Jakob Massling, Andreas Hansson, Hans-Christen Salzen, Knut Skov, Henrik Andrews, Elisabeth Quinn, Patricia K. Upchurch, Lucia M. Eleftheriadis, Konstantinos Traversi, Rita Gilardoni, Stefania Mazzola, Mauro Laing, James Hopke, Philip Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
author_facet |
Schmale, Julia Sharma, Sangeeta Decesari, Stefano Pernov, Jakob Massling, Andreas Hansson, Hans-Christen Salzen, Knut Skov, Henrik Andrews, Elisabeth Quinn, Patricia K. Upchurch, Lucia M. Eleftheriadis, Konstantinos Traversi, Rita Gilardoni, Stefania Mazzola, Mauro Laing, James Hopke, Philip |
author_sort |
Schmale, Julia |
title |
Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
title_short |
Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
title_full |
Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
title_fullStr |
Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
title_full_unstemmed |
Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
title_sort |
pan-arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories |
publishDate |
2022 |
url |
https://doi.org/10.5194/acp-22-3067-2022 https://acp.copernicus.org/articles/22/3067/2022/ |
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ENVELOPE(-59.828,-59.828,-63.497,-63.497) ENVELOPE(27.020,27.020,69.758,69.758) ENVELOPE(128.867,128.867,71.633,71.633) |
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Arctic Kendall Kevo Ny-Ålesund Tiksi |
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Arctic Kendall Kevo Ny-Ålesund Tiksi |
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albedo Arctic black carbon Climate change Ny Ålesund Ny-Ålesund Tiksi |
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albedo Arctic black carbon Climate change Ny Ålesund Ny-Ålesund Tiksi |
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eISSN: 1680-7324 |
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doi:10.5194/acp-22-3067-2022 https://acp.copernicus.org/articles/22/3067/2022/ |
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https://doi.org/10.5194/acp-22-3067-2022 |
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Atmospheric Chemistry and Physics |
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22 |
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5 |
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3067 |
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ftcopernicus:oai:publications.copernicus.org:acp97513 2023-05-15T13:11:33+02:00 Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories Schmale, Julia Sharma, Sangeeta Decesari, Stefano Pernov, Jakob Massling, Andreas Hansson, Hans-Christen Salzen, Knut Skov, Henrik Andrews, Elisabeth Quinn, Patricia K. Upchurch, Lucia M. Eleftheriadis, Konstantinos Traversi, Rita Gilardoni, Stefania Mazzola, Mauro Laing, James Hopke, Philip 2022-03-08 application/pdf https://doi.org/10.5194/acp-22-3067-2022 https://acp.copernicus.org/articles/22/3067/2022/ eng eng doi:10.5194/acp-22-3067-2022 https://acp.copernicus.org/articles/22/3067/2022/ eISSN: 1680-7324 Text 2022 ftcopernicus https://doi.org/10.5194/acp-22-3067-2022 2022-03-14T17:22:17Z Even though the Arctic is remote, aerosol properties observed there are strongly influenced by anthropogenic emissions from outside the Arctic. This is particularly true for the so-called Arctic haze season (January through April). In summer (June through September), when atmospheric transport patterns change, and precipitation is more frequent, local Arctic sources, i.e., natural sources of aerosols and precursors, play an important role. Over the last few decades, significant reductions in anthropogenic emissions have taken place. At the same time a large body of literature shows evidence that the Arctic is undergoing fundamental environmental changes due to climate forcing, leading to enhanced emissions by natural processes that may impact aerosol properties. In this study, we analyze 9 aerosol chemical species and 4 particle optical properties from 10 Arctic observatories (Alert, Kevo, Pallas, Summit, Thule, Tiksi, Barrow/Utqiaġvik, Villum, and Gruvebadet and Zeppelin Observatory – both at Ny-Ålesund Research Station) to understand changes in anthropogenic and natural aerosol contributions. Variables include equivalent black carbon, particulate sulfate, nitrate, ammonium, methanesulfonic acid, sodium, iron, calcium and potassium, as well as scattering and absorption coefficients, single scattering albedo and scattering Ångström exponent. First, annual cycles are investigated, which despite anthropogenic emission reductions still show the Arctic haze phenomenon. Second, long-term trends are studied using the Mann–Kendall Theil–Sen slope method. We find in total 41 significant trends over full station records, i.e., spanning more than a decade, compared to 26 significant decadal trends. The majority of significantly declining trends is from anthropogenic tracers and occurred during the haze period, driven by emission changes between 1990 and 2000. For the summer period, no uniform picture of trends has emerged. Twenty-six percent of trends, i.e., 19 out of 73, are significant, and of those 5 are positive and 14 are negative. Negative trends include not only anthropogenic tracers such as equivalent black carbon at Kevo, but also natural indicators such as methanesulfonic acid and non-sea-salt calcium at Alert. Positive trends are observed for sulfate at Gruvebadet. No clear evidence of a significant change in the natural aerosol contribution can be observed yet. However, testing the sensitivity of the Mann–Kendall Theil–Sen method, we find that monotonic changes of around 5 % yr −1 in an aerosol property are needed to detect a significant trend within one decade. This highlights that long-term efforts well beyond a decade are needed to capture smaller changes. It is particularly important to understand the ongoing natural changes in the Arctic, where interannual variability can be high, such as with forest fire emissions and their influence on the aerosol population. To investigate the climate-change-induced influence on the aerosol population and the resulting climate feedback, long-term observations of tracers more specific to natural sources are needed, as well as of particle microphysical properties such as size distributions, which can be used to identify changes in particle populations which are not well captured by mass-oriented methods such as bulk chemical composition. Text albedo Arctic black carbon Climate change Ny Ålesund Ny-Ålesund Tiksi Copernicus Publications: E-Journals Arctic Kendall ENVELOPE(-59.828,-59.828,-63.497,-63.497) Kevo ENVELOPE(27.020,27.020,69.758,69.758) Ny-Ålesund Tiksi ENVELOPE(128.867,128.867,71.633,71.633) Atmospheric Chemistry and Physics 22 5 3067 3096 |