The driving of baroclinic anomalies at different timescales
The driving of baroclinic anomalies at different timescales
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DOI：
10.1029/2011gl049785
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发表时间：
2011-12
影响因子：
5.2
通讯作者：
Javier Blanco-Fuentes;P. Zurita‐Gotor
中科院分区：
文献类型：
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作者：
Javier Blanco-Fuentes;P. Zurita‐Gotor
这项工作研究了南半球中纬度地区纬向平均斜压性的内部变化。前两个主导模态描述了纬向斜压性的转变和斜压性的锐化/加宽，在低频下这种转变变得更加主导。用滞后回归分析方法估计的斜压异常的生命周期随频率范围的不同而有质的不同。在高频率下，纬向平均斜压性仅响应于快速涡动热通量强迫。在低频，涡动动量通量通过涡动驱动的平均纬向环流强迫斜压性移动，并使其非绝热阻尼。行星尺度涡旋引起的纬向涡动热通量也对低频偏移有贡献，但天气尺度涡动热通量表现为扩散性，并在低频抑制斜压性异常。
This work investigates the internal variability of zonal‐mean baroclinicity over the Southern Hemisphere midlatitudes. The first two leading modes describe a meridional baroclinicity shift and a sharpening/broadening of baroclinicity, with the shift becoming more dominant at low frequency. The lifecycles of the baroclinic anomalies, estimated by means of lagged regression analysis, are qualitatively different depending on the frequency range. At high frequency, the zonal‐mean baroclinicity simply responds to the fast eddy heat flux forcing. At low frequency, the baroclinicity shift is forced by the eddy momentum flux through an eddy driven mean meridional circulation and damped diabatically. The meridional eddy heat flux by planetary scale eddies also contributes to the low‐frequency shift but the synoptic eddy heat flux behaves diffusively and damps the baroclinicity anomalies at low frequency.