Regional Contrast in Temperature Extremes Associated with the Ural Anticyclonic Height Anomaly under the Progression of Global Warming

抄録

Using a large-ensemble climate simulation, this study examines how global warming influences temperature extremes associated with the Ural anticyclonic height anomaly. A comparison of 4K global warming and non-warming experiments exhibits an increased frequency of Ural blocking events. These events produce a dipole temperature anomaly pattern, with pronounced warming in the Eurasian Arctic coast and cooling in the Eurasian mid-latitudes. This meridionally displaced warm and cold temperature anomalies arise from the anticyclonic height anomaly in the Ural region acting upon the climatological northwest-southeast isotherms. Under 4K warming, the frequency distribution of near-surface temperature anomaly reveals suppression of extreme warm anomalies in the Arctic coast while cold extremes in the mid-latitudes remain robust. This regional contrast stems from the zonally symmetric amplification of Arctic warming interacting with the tilted climatological isotherms in the Ural region. Enhanced high-latitude warming reduces the meridional temperature gradient in the Arctic coast, leading to weaker temperature advection associated with the Ural anticyclonic height anomaly which suppresses the warm extremes. In comparison, the mid-latitude temperature gradient remains less affected, preserving the frequency distribution of the cold anomalies.