The impact of polar warming on global atmospheric circulation and mid-latitude baroclinic waves
Abstract. The results of experimental and numerical modeling of Arctic warming in a laboratory dishpan configuration are presented. The Arctic warming is reproduced by varying the size of a local cooler in the "atmospheric" regime, in which the flow structure is similar to the general atmospheric circulation. It is shown that a significant variation in cooling power and boundary (slip and non-slip) conditions leads to quantitative changes in the structure and intensity of baroclinic waves. The size of the cooler and boundary conditions applied to its surface play a crucial role in the structure and intensity of circulation at small radii. The laboratory Arctic warming leads to a weakening of a polar cell analog and mean zonal flows. The most important result of this study is a noticeable transformation of the mean temperature field. Namely, the central region and most of the lower layer become warmer, while most of the upper layer and the peripheral (equatorial) part of the lower layer become colder. The nature of this phenomenon is closely related to the changes in radial heat fluxes. Laboratory Arctic warming leads to a significant decrease in the negative heat flux near the bottom, which inevitably leads to an increase in temperature. Our results provide a plausible explanation for Arctic warming amplification.
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