2019/07/01 by Lei Wang, Wang, Lei, Zhiming Kuang +1
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #Atmospheric and Oceanic Physics (physics.ao-ph) #FOS: Physical sciences #Fluid Dynamics and Turbulent Flows #Solar and Space Plasma Dynamics #Tropical and Extratropical Cyclones Research #physics.ao-ph
paper · pdf · doi:10.48550/arxiv.1907.00999
arxiv created 2019/07/01 · openalex publication_date 2019/07/01 · arxiv updated 2019/07/03 · openalex created_date 2022/07/12 · openalex updated_date 2026/07/28
The eddy straining mechanism of Shutts (1983; S83) has long been considered a main process for explaining the maintenance of atmospheric blocking. As hypothesized in S83, incoming synoptic eddies experience a meridional straining effect when approaching a split jetstream, and as a result, enhanced PV fluxes reinforce the block. A two-layer QG model is adopted here as a minimal model to conduct mechanism-denial experiments. While transient eddies' forcing is clearly critical to the formation and maintenance of a block, using a large ensemble, the authors demonstrate that the straining of generic eddies does not maintain blocks, thus challenge the idea of eddy straining serving as a positive feedback for the blocks. These results indicate that specific configurations of the eddy field are required for the maintenance stage. The authors also remark on the main supporting evidence in S83: the second-order induced flow is sensitive to the location of the wavemaker.