Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer
<p>The process of mixing in warm convective clouds and its effects on microphysics are crucial for an accurate description of cloud fields, weather, and climate. Still, they remain open questions in the field of cloud physics. Adiabatic regions in the cloud could be considered non-mixed areas...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/16203/2021/acp-21-16203-2021.pdf |
| _version_ | 1818568283689844736 |
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| author | E. Eytan I. Koren O. Altaratz M. Pinsky A. Khain |
| author_facet | E. Eytan I. Koren O. Altaratz M. Pinsky A. Khain |
| author_sort | E. Eytan |
| collection | DOAJ |
| description | <p>The process of mixing in warm convective clouds and its effects on microphysics are crucial for an accurate description of cloud fields, weather, and climate. Still, they remain open questions in the field of cloud physics. Adiabatic regions in the cloud could be considered non-mixed areas and therefore serve as an important reference to mixing. For this reason, the adiabatic fraction (AF) is an important parameter that estimates the mixing level in the cloud in a simple way.
Here, we test different methods of AF calculations using high-resolution (10 m) simulations of isolated warm cumulus clouds. The calculated AFs are compared with a normalized concentration of a passive tracer, which is a measure of dilution by mixing. This comparison enables the examination of how well the AF parameter can determine mixing effects and the estimation of the accuracy of different approaches used to calculate it. Comparison of three different methods to derive AF, with the passive tracer, shows that one method is much more robust than the others. Moreover, this method's equation structure also allows for the isolation of different assumptions that are often practiced when calculating AF such as vertical profiles, cloud-base height, and the linearity of AF with height. The use of a detailed spectral bin microphysics scheme allows an accurate description of the supersaturation field and demonstrates that the accuracy of the saturation adjustment assumption depends on aerosol concentration, leading to an underestimation of AF in pristine environments.</p> |
| first_indexed | 2024-12-14T06:33:49Z |
| format | Article |
| id | doaj.art-49eb6ec7e4e34488b8fd107d38529d6f |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-14T06:33:49Z |
| publishDate | 2021-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-49eb6ec7e4e34488b8fd107d38529d6f2022-12-21T23:13:26ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-11-0121162031621710.5194/acp-21-16203-2021Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracerE. Eytan0I. Koren1O. Altaratz2M. Pinsky3A. Khain4Department of Earth and Planetary Science, Weizmann Institute of Science, Rehovot, IsraelDepartment of Earth and Planetary Science, Weizmann Institute of Science, Rehovot, IsraelDepartment of Earth and Planetary Science, Weizmann Institute of Science, Rehovot, IsraelInstitute of Earth Science, Hebrew University, Jerusalem, IsraelInstitute of Earth Science, Hebrew University, Jerusalem, Israel<p>The process of mixing in warm convective clouds and its effects on microphysics are crucial for an accurate description of cloud fields, weather, and climate. Still, they remain open questions in the field of cloud physics. Adiabatic regions in the cloud could be considered non-mixed areas and therefore serve as an important reference to mixing. For this reason, the adiabatic fraction (AF) is an important parameter that estimates the mixing level in the cloud in a simple way. Here, we test different methods of AF calculations using high-resolution (10 m) simulations of isolated warm cumulus clouds. The calculated AFs are compared with a normalized concentration of a passive tracer, which is a measure of dilution by mixing. This comparison enables the examination of how well the AF parameter can determine mixing effects and the estimation of the accuracy of different approaches used to calculate it. Comparison of three different methods to derive AF, with the passive tracer, shows that one method is much more robust than the others. Moreover, this method's equation structure also allows for the isolation of different assumptions that are often practiced when calculating AF such as vertical profiles, cloud-base height, and the linearity of AF with height. The use of a detailed spectral bin microphysics scheme allows an accurate description of the supersaturation field and demonstrates that the accuracy of the saturation adjustment assumption depends on aerosol concentration, leading to an underestimation of AF in pristine environments.</p>https://acp.copernicus.org/articles/21/16203/2021/acp-21-16203-2021.pdf |
| spellingShingle | E. Eytan I. Koren O. Altaratz M. Pinsky A. Khain Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer Atmospheric Chemistry and Physics |
| title | Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer |
| title_full | Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer |
| title_fullStr | Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer |
| title_full_unstemmed | Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer |
| title_short | Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer |
| title_sort | revisiting adiabatic fraction estimations in cumulus clouds high resolution simulations with a passive tracer |
| url | https://acp.copernicus.org/articles/21/16203/2021/acp-21-16203-2021.pdf |
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