Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability
Abstract We modify the Zhang‐McFarlane (ZM) deep convection scheme in the Community Atmosphere Model version 5 to couple it with a unified parameterization for boundary‐layer turbulence and shallow convection, that is, Cloud Layers Unified by Binormals (CLUBB). By assuming a lognormal distribution o...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2021-05-01
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| Series: | Journal of Advances in Modeling Earth Systems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2020MS002357 |
| _version_ | 1819040397210419200 |
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| author | Ben Yang Minghuai Wang Guang J. Zhang Zhun Guo Anning Huang Yaocun Zhang Yun Qian |
| author_facet | Ben Yang Minghuai Wang Guang J. Zhang Zhun Guo Anning Huang Yaocun Zhang Yun Qian |
| author_sort | Ben Yang |
| collection | DOAJ |
| description | Abstract We modify the Zhang‐McFarlane (ZM) deep convection scheme in the Community Atmosphere Model version 5 to couple it with a unified parameterization for boundary‐layer turbulence and shallow convection, that is, Cloud Layers Unified by Binormals (CLUBB). By assuming a lognormal distribution of entrainment rate across the entire moist convective regimes, we link mass fluxes between shallow and deep convection, which are partitioned by the entrainment rate of the shallowest deep convective plume. Hence, a new deep convective closure is established which is coupled to the sub‐grid vertical motion variability in CLUBB. The convection feedback (or memory) effects are also considered to decrease the entrainment spectrum width and enhance the vertical velocity variability that further affect deep convection. Results show that the revised scheme improves the precipitation simulations in terms of the mean state and variability at various timescales, such as the alleviated double‐intertropical convergence zone and more realistic simulations of the seasonal variation of monsoon precipitation over East Asia, Madden‐Julian Oscillation, and precipitation diurnal phase propagations downstream of large terrains. The improvements are still seen in many aspects such as the mean‐state precipitation when turning off the convection feedback impacts in the revised scheme, emphasizing the benefits of using the modified mass‐flux closure. However, the convection feedbacks have considerable effects on the precipitation diurnal cycle simulations over regions with late‐afternoon precipitation peaks. Overall, the revised scheme provides a unified treatment for sub‐grid vertical motions across regimes of boundary‐layer turbulence, shallow convection, and deep convection, leading to better‐simulated precipitation at various timescales. |
| first_indexed | 2024-12-21T09:08:27Z |
| format | Article |
| id | doaj.art-8e329982bddc4c6ba49eb5cb12913354 |
| institution | Directory Open Access Journal |
| issn | 1942-2466 |
| language | English |
| last_indexed | 2024-12-21T09:08:27Z |
| publishDate | 2021-05-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj.art-8e329982bddc4c6ba49eb5cb129133542022-12-21T19:09:16ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662021-05-01135n/an/a10.1029/2020MS002357Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation VariabilityBen Yang0Minghuai Wang1Guang J. Zhang2Zhun Guo3Anning Huang4Yaocun Zhang5Yun Qian6School of Atmospheric Sciences Nanjing University Nanjing ChinaSchool of Atmospheric Sciences Nanjing University Nanjing ChinaScripps Institution of Oceanography University of California La Jolla San Diego CA USAState Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing ChinaSchool of Atmospheric Sciences Nanjing University Nanjing ChinaSchool of Atmospheric Sciences Nanjing University Nanjing ChinaPacific Northwest National Laboratory Richland Washington USAAbstract We modify the Zhang‐McFarlane (ZM) deep convection scheme in the Community Atmosphere Model version 5 to couple it with a unified parameterization for boundary‐layer turbulence and shallow convection, that is, Cloud Layers Unified by Binormals (CLUBB). By assuming a lognormal distribution of entrainment rate across the entire moist convective regimes, we link mass fluxes between shallow and deep convection, which are partitioned by the entrainment rate of the shallowest deep convective plume. Hence, a new deep convective closure is established which is coupled to the sub‐grid vertical motion variability in CLUBB. The convection feedback (or memory) effects are also considered to decrease the entrainment spectrum width and enhance the vertical velocity variability that further affect deep convection. Results show that the revised scheme improves the precipitation simulations in terms of the mean state and variability at various timescales, such as the alleviated double‐intertropical convergence zone and more realistic simulations of the seasonal variation of monsoon precipitation over East Asia, Madden‐Julian Oscillation, and precipitation diurnal phase propagations downstream of large terrains. The improvements are still seen in many aspects such as the mean‐state precipitation when turning off the convection feedback impacts in the revised scheme, emphasizing the benefits of using the modified mass‐flux closure. However, the convection feedbacks have considerable effects on the precipitation diurnal cycle simulations over regions with late‐afternoon precipitation peaks. Overall, the revised scheme provides a unified treatment for sub‐grid vertical motions across regimes of boundary‐layer turbulence, shallow convection, and deep convection, leading to better‐simulated precipitation at various timescales.https://doi.org/10.1029/2020MS002357CLUBBdeep and shallow convectionentrainment distributionmass fluxprecipitation simulationZhang‐McFarlane parameterization |
| spellingShingle | Ben Yang Minghuai Wang Guang J. Zhang Zhun Guo Anning Huang Yaocun Zhang Yun Qian Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability Journal of Advances in Modeling Earth Systems CLUBB deep and shallow convection entrainment distribution mass flux precipitation simulation Zhang‐McFarlane parameterization |
| title | Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability |
| title_full | Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability |
| title_fullStr | Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability |
| title_full_unstemmed | Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability |
| title_short | Linking Deep and Shallow Convective Mass Fluxes via an Assumed Entrainment Distribution in CAM5‐CLUBB: Parameterization and Simulated Precipitation Variability |
| title_sort | linking deep and shallow convective mass fluxes via an assumed entrainment distribution in cam5 clubb parameterization and simulated precipitation variability |
| topic | CLUBB deep and shallow convection entrainment distribution mass flux precipitation simulation Zhang‐McFarlane parameterization |
| url | https://doi.org/10.1029/2020MS002357 |
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