资源环境科技发展态势分析平台

Reduced Arctic sea-ice has been proposed to induce severe Eurasian cold events. However, the physical mechanisms for this connection, particularly the relative importance of tropospheric and stratospheric processes, remain unclear. Using ERA-Interim reanalysis data and WACCM-SC simulations, we show that the Eurasian cooling induced by reduced sea-ice centers over eastern Asia and northern Europe. Tropospheric and stratospheric processes contribute roughly equally to the cooling over eastern Asia, while the stratospheric and tropospheric contributions are 60% and 40%, respectively, over northern Europe. In the tropospheric pathway, weakened meridional temperature gradient due to reduced sea-ice strengthens the Ural blocking and enhances the Siberian High. The enhanced Siberian High favors two streams of cold air-mass, reaching northern Europe and eastern Asia. In the stratospheric pathway, enhanced upward-propagating planetary wave 1 causes a shift of the stratospheric polar vortex towards Eurasia and consequently, tropospheric cyclonic anomalies are induced that enhance surface cold anomalies.