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DOI | 10.1175/JAS-D-18-0136.1 |
An Adiabatic Mechanism for the Reduction of Jet Meander Amplitude by Potential Vorticity Filamentation | |
Harvey, Ben1; Methven, John2; Ambaum, Maarten H. P.2 | |
2018-12-01 | |
发表期刊 | JOURNAL OF THE ATMOSPHERIC SCIENCES |
ISSN | 0022-4928 |
EISSN | 1520-0469 |
出版年 | 2018 |
卷号 | 75期号:12页码:4091-4106 |
文章类型 | Article |
语种 | 英语 |
国家 | England |
英文摘要 | The amplitude of ridges in large-amplitude Rossby waves has been shown to decrease systematically with lead time during the first 1-5 days of operational global numerical weather forecasts. These models also exhibit a rapid reduction in the isentropic gradient of potential vorticity (PV) at the tropopause during the first 1-2 days of forecasts. This paper identifies a mechanism linking the reduction in large-scale meander amplitude on jet streams to declining PV gradients. The mechanism proposed is that a smoother isentropic transition of PV across the tropopause leads to excessive PV filamentation on the jet flanks and a more lossy waveguide. The approach taken is to analyze Rossby wave dynamics in a single-layer quasigeostrophic model. Numerical simulations show that the amplitude of a Rossby wave propagating along a narrow but smooth PV front does indeed decay transiently with time. This process is explained in terms of the filamentation of PV from the jet core and associated absorption of wave activity by the critical layers on the jet flanks, and a simple method for quantitatively predicting the magnitude of the amplitude reduction without simulation is presented. Explicitly diffusive simulations are then used to show that the combined impact of diffusion and the adiabatic rearrangement of PV can result in a decay rate of Rossby waves that is 2-4 times as fast as could be expected from diffusion acting alone. This predicted decay rate is sufficient to explain the decay observed in operational weather forecasting models. |
英文关键词 | Momentum Nonlinear dynamics Potential vorticity Rossby waves Shallow-water equations Jets |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000449625500001 |
WOS关键词 | ROSSBY WAVES ; KEY ROLE ; FLOWS ; INSTABILITY ; EVOLUTION ; DYNAMICS ; ERROR |
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/29741 |
专题 | 地球科学 |
作者单位 | 1.Univ Reading, Natl Ctr Atmospher Sci, Reading, Berks, England; 2.Univ Reading, Dept Meteorol, Reading, Berks, England |
推荐引用方式 GB/T 7714 | Harvey, Ben,Methven, John,Ambaum, Maarten H. P.. An Adiabatic Mechanism for the Reduction of Jet Meander Amplitude by Potential Vorticity Filamentation[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2018,75(12):4091-4106. |
APA | Harvey, Ben,Methven, John,&Ambaum, Maarten H. P..(2018).An Adiabatic Mechanism for the Reduction of Jet Meander Amplitude by Potential Vorticity Filamentation.JOURNAL OF THE ATMOSPHERIC SCIENCES,75(12),4091-4106. |
MLA | Harvey, Ben,et al."An Adiabatic Mechanism for the Reduction of Jet Meander Amplitude by Potential Vorticity Filamentation".JOURNAL OF THE ATMOSPHERIC SCIENCES 75.12(2018):4091-4106. |
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