An extreme cold wave event is analyzed on the isentropic potential vorticity (IPV) with the FNL reanalysis data from 1 Jan to 31 Jan 2016.The result shows that high potential vorticity (PV) was resulted from the splitting polar vortex, and the blocking of the front low PV and the proceeding northward moving of the rear low PV strengthened the meridional exchange of the PV.The high PV air continuously moved from the polar to the south, making the main body of the high PV continue to strengthen, and meanwhile, the high vortex also transported downward from the troposphere.The cold wave, which included three strands of cold air, developed from the upper to the bottom, settling in the north side of the upper-level jet.In the southern tip a sinking airflow was most exuberant, which resulted from its interaction with the upper-level jet.The sinking of the strong cold air made the cold wave influence the South China.As the high PV transmitted towards the south area, the low vortex system developed rapidly in the high-level troposphere.When it moved to the eastern China, The East Asian Trough deepened rapidly, and finally induced the outbreak of strong cold air behind the trough.On the other hand, in the process of high PV transportation, the rear strongly sinking movement occurred to render the rapid development of the cold high on the ground and lead to the outbreak of cold wave weather.%利用2016年1月1日至31日的FNL资料, 对一次极端寒潮天气过程进行了等熵位涡分析.结果表明:高位涡主体由极涡分裂而来, 前面低位涡区的阻挡与后侧低位涡大气的北上加强了位涡的经向交换, 高位涡空气不断由极地向南输送, 使得高位涡主体不断加强维持.高位涡在由北向南移动的同时, 也由对流层顶向下输送.此次寒潮过程主要有3股冷空气由上而下发展, 位置均在高空急流轴的北侧, 最南端的一股下沉气流最旺盛, 这是其与高空急流相互作用的结果.强盛的冷空气下沉使得寒潮影响范围触及我国华南地区.随着高位涡的向南向下传输, 一方面引起对流层中高层低涡系统迅速发展, 当它移到中国东部地区时, 东亚大槽迅速加深, 使槽后强冷空气迅速向南爆发;另一方面, 在高位涡输送的过程中, 其后侧有强烈的下沉运动, 使得地面冷高压快速发展, 导致强寒潮天气的爆发.
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