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DOI | 10.1175/JCLI-D-17-0644.1 |
Eddy Lifetime, Number, and Diffusivity and the Suppression of Eddy Kinetic Energy in Midwinter | |
Schemm, Sebastian1,2,3; Schneider, Tapio4 | |
2018-07-01 | |
发表期刊 | JOURNAL OF CLIMATE |
ISSN | 0894-8755 |
EISSN | 1520-0442 |
出版年 | 2018 |
卷号 | 31期号:14页码:5649-5665 |
文章类型 | Article |
语种 | 英语 |
国家 | Norway; Switzerland; USA |
英文摘要 | The wintertime evolution of the North Pacific storm track appears to challenge classical theories of baroclinic instability, which predict deeper extratropical cyclones when baroclinicity is highest. Although the surface baroclinicity peaks during midwinter, and the jet is strongest, eddy kinetic energy (EKE) and baroclinic conversion rates have a midwinter minimum over the North Pacific. This study investigates how the reduction in EKE translates into a reduction in eddy potential vorticity (PV) and heat fluxes via changes in eddy diffusivity. Additionally, it augments previous observations of the midwinter storm-track evolution in both hemispheres using climatologies of tracked surface cyclones. In the North Pacific, the number of surface cyclones is highest during midwinter, while the mean EKE per cyclone and the eddy lifetime are reduced. The midwinter reduction in upper-level eddy activity hence is not associated with a reduction in surface cyclone numbers. North Pacific eddy diffusivities exhibit a midwinter reduction at upper levels, where the Lagrangian decorrelation time is shortest (consistent with reduced eddy lifetimes) and the meridional parcel velocity variance is reduced (consistent with reduced EKE). The resulting midwinter reduction in North Pacific eddy diffusivities translates into an eddy PV flux suppression. In contrast, in the North Atlantic, a milder reduction in the decorrelation time is offset by a maximum in velocity variance, preventing a midwinter diffusivity minimum. The results suggest that a focus on causes of the wintertime evolution of Lagrangian decorrelation times and parcel velocity variance will be fruitful for understanding causes of seasonal storm-track variations. |
英文关键词 | Atmosphere Extratropical cyclones Lagrangian circulation transport Storm tracks Kinetic energy Seasonal cycle |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000435926900002 |
WOS关键词 | PACIFIC STORM TRACK ; ATMOSPHERIC MOISTURE TRANSPORT ; NORTH-PACIFIC ; SOUTHERN-HEMISPHERE ; CLIMATE-CHANGE ; ERA-INTERIM ; CYCLONES ; VARIABILITY ; DYNAMICS ; EDDIES |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/20158 |
专题 | 气候变化 |
作者单位 | 1.Univ Bergen, Inst Geophys, Bergen, Norway; 2.Univ Bergen, Bjerknes Ctr Climate Res, Bergen, Norway; 3.Swiss Fed Inst Technol, Inst Atmospher & Climate Sci, Zurich, Switzerland; 4.CALTECH, Pasadena, CA 91125 USA |
推荐引用方式 GB/T 7714 | Schemm, Sebastian,Schneider, Tapio. Eddy Lifetime, Number, and Diffusivity and the Suppression of Eddy Kinetic Energy in Midwinter[J]. JOURNAL OF CLIMATE,2018,31(14):5649-5665. |
APA | Schemm, Sebastian,&Schneider, Tapio.(2018).Eddy Lifetime, Number, and Diffusivity and the Suppression of Eddy Kinetic Energy in Midwinter.JOURNAL OF CLIMATE,31(14),5649-5665. |
MLA | Schemm, Sebastian,et al."Eddy Lifetime, Number, and Diffusivity and the Suppression of Eddy Kinetic Energy in Midwinter".JOURNAL OF CLIMATE 31.14(2018):5649-5665. |
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