Nan Lin, Tuantuan Zhang, Qiaoling Ren, Ho-Nam Cheung, Chang-Hoi Ho, Song Yang. 2025: Interactions of the Background State and Eddies in Shaping Aleutian Low Variations. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-024-4385-2
Citation: Nan Lin, Tuantuan Zhang, Qiaoling Ren, Ho-Nam Cheung, Chang-Hoi Ho, Song Yang. 2025: Interactions of the Background State and Eddies in Shaping Aleutian Low Variations. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-024-4385-2

Interactions of the Background State and Eddies in Shaping Aleutian Low Variations

  • The Aleutian Low (AL) is a dominant feature of the mean circulation in the North Pacific during the winter season. The background stationary wave, air-sea interaction, and transient eddies over the North Pacific exert distinct impacts on the interannual variations of the AL intensity and position. In this study, we adopt the quasi-geostrophic geopotential tendency equation to investigate the roles of various physical processes in the maintenance and interannual variations of this system. The results show that the absolute vorticity advection plays the most important role in the formation and maintenance of AL intensity, while the high-frequency transient eddies contribute most to the meridional and zonal shifts of the AL. The high-frequency transient eddy vorticity forcing affects the AL through barotropic energy conversion process, and in turn the AL enhances the high-frequency transient eddies through baroclinic energy conversion process, forming a positive feedback. The associated high-frequency eddy kinetic energy anomalies exhibit an eastward movement to the east coast of North America in the years of intensified AL, which explains why the strengthened AL is often accompanied by an eastward movement. Furthermore, the energy conversion terms of high-frequency transient eddies are mostly located over the extratropical eastern North Pacific, leading to asymmetric features in the zonal movement of the AL.
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