Xiao-Ming Hu, Greg M. McFarquhar, Bowen Zhou, Ming Xue
{"title":"常规和质量通量PBL方案模拟南大洋云边界层耦合三种模式的性能","authors":"Xiao-Ming Hu, Greg M. McFarquhar, Bowen Zhou, Ming Xue","doi":"10.1029/2025JD043679","DOIUrl":null,"url":null,"abstract":"<p>Planetary boundary layer (PBL) structure over the ocean and the model capability to simulate such structure are less well-understood than their counterparts over land. In this study, observations and WRF simulations are examined to study the boundary layer structure over the Southern Ocean, focusing on the coupling between the oceanic boundary layer and the cloud layer above. Based on the lower tropospheric vertical profiles and cross-sections, three cloud-boundary layer coupling modes are identified including a coupled mode with a weak positive surface heat flux (type 1), and two decoupled modes in the presence of either a negative surface heat flux driving a shallow stable boundary layer (type 2) or a strong positive surface heat flux (type 3). Numerical simulations are conducted for representative cases of each mode using the conventional YSU PBL scheme without and with the cloud-induced top-down mixing option (referred to as YSUtopdown), as well as the MYNN and the MYNN eddy-diffusivity mass-flux scheme (MYNN-EDMF) that adopts a holistic treatment of mixed-layer thermals and shallow convective clouds. The MYNN-EDMF scheme offers the best representation of the decoupled type 3 mode where its capability to simulate different vertical extents of local mixing and nonlocal mass flux is found to be essential. Two key parameters in MYNN-EDMF dictating shallow cloud formation are also identified. The YSUtopdown scheme develops a deeper boundary layer than the YSU scheme and exhibits more consistency with observations for the coupled type 1 mode. For the decoupled type 2 mode, all four schemes perform similarly well.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8000,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Performance of Conventional and Mass-Flux PBL Schemes for Simulating Three Modes of Cloud-Boundary Layer Coupling Over the Southern Ocean\",\"authors\":\"Xiao-Ming Hu, Greg M. McFarquhar, Bowen Zhou, Ming Xue\",\"doi\":\"10.1029/2025JD043679\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Planetary boundary layer (PBL) structure over the ocean and the model capability to simulate such structure are less well-understood than their counterparts over land. In this study, observations and WRF simulations are examined to study the boundary layer structure over the Southern Ocean, focusing on the coupling between the oceanic boundary layer and the cloud layer above. Based on the lower tropospheric vertical profiles and cross-sections, three cloud-boundary layer coupling modes are identified including a coupled mode with a weak positive surface heat flux (type 1), and two decoupled modes in the presence of either a negative surface heat flux driving a shallow stable boundary layer (type 2) or a strong positive surface heat flux (type 3). Numerical simulations are conducted for representative cases of each mode using the conventional YSU PBL scheme without and with the cloud-induced top-down mixing option (referred to as YSUtopdown), as well as the MYNN and the MYNN eddy-diffusivity mass-flux scheme (MYNN-EDMF) that adopts a holistic treatment of mixed-layer thermals and shallow convective clouds. The MYNN-EDMF scheme offers the best representation of the decoupled type 3 mode where its capability to simulate different vertical extents of local mixing and nonlocal mass flux is found to be essential. Two key parameters in MYNN-EDMF dictating shallow cloud formation are also identified. The YSUtopdown scheme develops a deeper boundary layer than the YSU scheme and exhibits more consistency with observations for the coupled type 1 mode. For the decoupled type 2 mode, all four schemes perform similarly well.</p>\",\"PeriodicalId\":15986,\"journal\":{\"name\":\"Journal of Geophysical Research: Atmospheres\",\"volume\":\"130 9\",\"pages\":\"\"},\"PeriodicalIF\":3.8000,\"publicationDate\":\"2025-05-02\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Geophysical Research: Atmospheres\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1029/2025JD043679\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"METEOROLOGY & ATMOSPHERIC SCIENCES\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Atmospheres","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2025JD043679","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"METEOROLOGY & ATMOSPHERIC SCIENCES","Score":null,"Total":0}
Performance of Conventional and Mass-Flux PBL Schemes for Simulating Three Modes of Cloud-Boundary Layer Coupling Over the Southern Ocean
Planetary boundary layer (PBL) structure over the ocean and the model capability to simulate such structure are less well-understood than their counterparts over land. In this study, observations and WRF simulations are examined to study the boundary layer structure over the Southern Ocean, focusing on the coupling between the oceanic boundary layer and the cloud layer above. Based on the lower tropospheric vertical profiles and cross-sections, three cloud-boundary layer coupling modes are identified including a coupled mode with a weak positive surface heat flux (type 1), and two decoupled modes in the presence of either a negative surface heat flux driving a shallow stable boundary layer (type 2) or a strong positive surface heat flux (type 3). Numerical simulations are conducted for representative cases of each mode using the conventional YSU PBL scheme without and with the cloud-induced top-down mixing option (referred to as YSUtopdown), as well as the MYNN and the MYNN eddy-diffusivity mass-flux scheme (MYNN-EDMF) that adopts a holistic treatment of mixed-layer thermals and shallow convective clouds. The MYNN-EDMF scheme offers the best representation of the decoupled type 3 mode where its capability to simulate different vertical extents of local mixing and nonlocal mass flux is found to be essential. Two key parameters in MYNN-EDMF dictating shallow cloud formation are also identified. The YSUtopdown scheme develops a deeper boundary layer than the YSU scheme and exhibits more consistency with observations for the coupled type 1 mode. For the decoupled type 2 mode, all four schemes perform similarly well.
期刊介绍:
JGR: Atmospheres publishes articles that advance and improve understanding of atmospheric properties and processes, including the interaction of the atmosphere with other components of the Earth system.