【摘要】 2018年东北亚经历了过去40年以来最热的夏季(7–8月),其夏季平均的地表气温异常(1.2°C)几乎达到该地区气温年际标准差的2倍。本文指出此次极端高温与东北亚上空深厚的位势高度正异常有关,在分析时段内(1979–2018年)其强度在2018年最强。回归分析结果表明,北欧和里海的高层环流异常都可以通过激发下游波列对东北亚上空的环流产生重要影响。特别的是,2018年夏季北欧和里海的位势高度均显著增强,且均遭遇了极端高温的侵袭,位势高度正异常和高温异常也在分析时段内达到最强,因而通过波列共同促成了东北亚极端的位势高度正异常和高温。本文研究结果说明,为全面了解东北亚地区的温度变率,对中高纬的两种遥相关型特别是其波源的理解至关重要,值得进一步研究。更多还原

【Abstract】 This study investigated the contributions of mid–high-latitude circulation anomalies to the extremely hot summer(July and August; JA) of 2018 over Northeast Asia(NEA). The JA-mean surface air temperature in 2018 was 1.2°C higher than that of the 1979–2018 climatology, with the amplitude of such an anomaly almost doubling the interannual standard deviation, making 2018 the hottest year during the analysis period 1979–2018. The abnormal warming over NEA was caused by a local positive geopotential height anomaly reaching strongest intensity in JA 2018. Further investigation suggested that the upper-tropospheric circulation anomalies over northern Europe and the Caspian Sea were crucial to forming this NEA circulation anomaly through initiating downstream wave trains. Particularly, the geopotential heights over these two regions were concurrently at their highest in JA 2018, and therefore jointly contributed to the profound circulation anomaly over NEA and the hottest summer on record. Due to these two teleconnection patterns, the temperature anomalies in NEA are closely related to those in both northern Europe and the Caspian Sea, where the similarly extreme warming also happened in 2018.更多还原