Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations
<p>Mixed-phase clouds are ubiquitous in the Arctic. These clouds can persist for days and dissipate in a matter of hours. It is sometimes unknown what causes this sudden dissipation, but aerosol–cloud interactions may be involved. Arctic aerosol concentrations can be low enough to affect cloud...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/8973/2022/acp-22-8973-2022.pdf |
| _version_ | 1811297134942617600 |
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| author | L. J. Sterzinger J. Sedlar J. Sedlar H. Guy H. Guy R. R. Neely III R. R. Neely III A. L. Igel |
| author_facet | L. J. Sterzinger J. Sedlar J. Sedlar H. Guy H. Guy R. R. Neely III R. R. Neely III A. L. Igel |
| author_sort | L. J. Sterzinger |
| collection | DOAJ |
| description | <p>Mixed-phase clouds are ubiquitous in the Arctic. These clouds can persist for days and dissipate in a matter of hours. It is sometimes unknown what
causes this sudden dissipation, but aerosol–cloud interactions may be involved. Arctic aerosol concentrations can be low enough to affect cloud
formation and structure, and it has been hypothesized that, in some instances, concentrations can drop below some critical value needed to maintain a cloud.</p>
<p>We use observations from a Department of Energy ARM site on the northern slope of Alaska at Oliktok Point (OLI), the Arctic Summer Cloud Ocean Study (ASCOS) field campaign in the high Arctic Ocean, and the Integrated Characterisation of Energy, Clouds, Atmospheric state, and Precipitation at Summit – Aerosol Cloud Experiment (ICECAPS-ACE) project at the NSF (National Science Foundation) Summit Station in Greenland (SMT) to identify one case per site where Arctic boundary layer clouds dissipated coincidentally with a decrease in surface aerosol concentrations. These cases are used to initialize idealized large eddy simulations (LESs) in which aerosol concentrations are held constant until, at a specified time, all aerosols are removed instantaneously – effectively creating an extreme case of aerosol-limited dissipation which represents the fastest a cloud could possibly dissipate via this process. These LESs are compared against the observed data to determine whether cases could, potentially, be dissipating due to insufficient aerosol. The OLI case's observed liquid water path (LWP) dissipated faster than its simulation, indicating that other processes are likely the primary drivers of the dissipation. The ASCOS and SMT observed LWP dissipated at similar rates to their respective simulations, suggesting that aerosol-limited dissipation may be occurring in these instances.</p>
<p>We also find that the microphysical response to this extreme aerosol forcing depends greatly on the specific case being simulated. Cases with
drizzling liquid layers are simulated to dissipate by accelerating precipitation when aerosol is removed while the case with a non-drizzling liquid layer dissipates quickly, possibly glaciating via the Wegener–Bergeron–Findeisen (WBF) process. The non-drizzling case is also more sensitive to ice-nucleating particle (INP) concentrations than the drizzling cases. Overall, the simulations suggest that aerosol-limited cloud dissipation in the Arctic is plausible and that
there are at least two microphysical pathways by which aerosol-limited dissipation can occur.</p> |
| first_indexed | 2024-04-13T05:59:32Z |
| format | Article |
| id | doaj.art-670b572225a94740b4ed3e95a6a27bac |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T05:59:32Z |
| publishDate | 2022-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-670b572225a94740b4ed3e95a6a27bac2022-12-22T02:59:29ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-07-01228973898810.5194/acp-22-8973-2022Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulationsL. J. Sterzinger0J. Sedlar1J. Sedlar2H. Guy3H. Guy4R. R. Neely III5R. R. Neely III6A. L. Igel7Department of Land, Air and Water Resources, University of California, Davis, Davis, California, USACooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USANOAA/Global Monitoring Laboratory, Boulder, Colorado, USANational Centre for Atmospheric Science, Leeds, UKSchool of Earth and Environment, University of Leeds, Leeds, UKNational Centre for Atmospheric Science, Leeds, UKSchool of Earth and Environment, University of Leeds, Leeds, UKDepartment of Land, Air and Water Resources, University of California, Davis, Davis, California, USA<p>Mixed-phase clouds are ubiquitous in the Arctic. These clouds can persist for days and dissipate in a matter of hours. It is sometimes unknown what causes this sudden dissipation, but aerosol–cloud interactions may be involved. Arctic aerosol concentrations can be low enough to affect cloud formation and structure, and it has been hypothesized that, in some instances, concentrations can drop below some critical value needed to maintain a cloud.</p> <p>We use observations from a Department of Energy ARM site on the northern slope of Alaska at Oliktok Point (OLI), the Arctic Summer Cloud Ocean Study (ASCOS) field campaign in the high Arctic Ocean, and the Integrated Characterisation of Energy, Clouds, Atmospheric state, and Precipitation at Summit – Aerosol Cloud Experiment (ICECAPS-ACE) project at the NSF (National Science Foundation) Summit Station in Greenland (SMT) to identify one case per site where Arctic boundary layer clouds dissipated coincidentally with a decrease in surface aerosol concentrations. These cases are used to initialize idealized large eddy simulations (LESs) in which aerosol concentrations are held constant until, at a specified time, all aerosols are removed instantaneously – effectively creating an extreme case of aerosol-limited dissipation which represents the fastest a cloud could possibly dissipate via this process. These LESs are compared against the observed data to determine whether cases could, potentially, be dissipating due to insufficient aerosol. The OLI case's observed liquid water path (LWP) dissipated faster than its simulation, indicating that other processes are likely the primary drivers of the dissipation. The ASCOS and SMT observed LWP dissipated at similar rates to their respective simulations, suggesting that aerosol-limited dissipation may be occurring in these instances.</p> <p>We also find that the microphysical response to this extreme aerosol forcing depends greatly on the specific case being simulated. Cases with drizzling liquid layers are simulated to dissipate by accelerating precipitation when aerosol is removed while the case with a non-drizzling liquid layer dissipates quickly, possibly glaciating via the Wegener–Bergeron–Findeisen (WBF) process. The non-drizzling case is also more sensitive to ice-nucleating particle (INP) concentrations than the drizzling cases. Overall, the simulations suggest that aerosol-limited cloud dissipation in the Arctic is plausible and that there are at least two microphysical pathways by which aerosol-limited dissipation can occur.</p>https://acp.copernicus.org/articles/22/8973/2022/acp-22-8973-2022.pdf |
| spellingShingle | L. J. Sterzinger J. Sedlar J. Sedlar H. Guy H. Guy R. R. Neely III R. R. Neely III A. L. Igel Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations Atmospheric Chemistry and Physics |
| title | Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations |
| title_full | Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations |
| title_fullStr | Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations |
| title_full_unstemmed | Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations |
| title_short | Do Arctic mixed-phase clouds sometimes dissipate due to insufficient aerosol? Evidence from comparisons between observations and idealized simulations |
| title_sort | do arctic mixed phase clouds sometimes dissipate due to insufficient aerosol evidence from comparisons between observations and idealized simulations |
| url | https://acp.copernicus.org/articles/22/8973/2022/acp-22-8973-2022.pdf |
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