The Anomalous Cold Vortex Activity in Northeast China during the Early Summer and the Low-frequency Variability of the Northern Hemispheric Atmosphere Circulation
The Anomalous Cold Vortex Activity in Northeast China during the Early Summer and the Low-frequency Variability of the Northern Hemispheric Atmosphere Circulation
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发表时间：
2010
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通讯作者：
Shen Bai-zhu
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作者：
Shen Bai-zhu
通过典型个例分析，探讨了初夏东北冷涡异常活动与北方低频变率的联系及其可能机制，结果表明：（1）初夏东北冷涡异常活动与乌拉尔山及日本附近持续性环流异常有较好的对应关系，在强冷涡年，乌拉尔山地区持续的阻塞型环流是由Rossby波能量色散和异常瞬变涡旋强迫共同维持的，一方面，一方面驱动极地冷空气向东北移动，另一方面通过Rossby波能量色散放大冷涡，弱冷涡年则基本相反。(2)It谐波分析和低频振荡分析表明，5 ~ 6月冷涡活动强（弱），东北地区以负涡度位相为主，这正好与向西移相对应北太平洋超长波槽东进，乌拉尔山脉附近的持续异常环流是由横跨北太平洋-北美-北大西洋，通过分散罗斯贝波能量。（3）5月绕乌拉尔山环流异常是初夏东北冷涡活动的前兆信号。
Based on the typical case analysis,the linkage between the anomalous cold vortex activity in Northeast China during the early summer and the Northern Hemisphere low-frequency variability and the possible underlying mechanism are investigated.It is shown that:(1)The anomalous cold vortex activity in Northeast China in the early summer is quite in concert with persistent circulation anomalies near the Ural Mountains and Japan.During the strong cold vortex year,the persistent blocking-type circulation around the Ural Mountains is maintained both by the Rossby wave energy dispersion and anomalous transient eddy forcing.It,on the one hand,drives the polar cold air to move toward Northeast China and,on the other hand,amplifies the cold vortex through the Rossby wave energy dispersion.For the weak cold vortex year,the situation is basically reversed.(2)It is shown in Harmonic analysis and low-frequency oscillation analysis that while the cold vortex activity is strong(weak)from May to June,positive(negative)vorticity phase prevails over Northeast China,which corresponds well to the westward shift(eastward advance)of the ultra-long wave trough over the North Pacific.The persistent anomaly circulation around the Ural Mountains is maintained by the standing waves across the North Pacific-North America-the North Atlantic,through dispersion of the Rossby wave energy.(3)The anomalous circulation around the Ural Mountains in May constitutes a precursory signal to the cold vortex activity in Northeast China in the early summer.