Propagation of Low-Frequency Oscillation over Eurasian Mid–High Latitude in Winter and Its Association with the Eurasian Teleconnection Pattern
Propagation of Low-Frequency Oscillation over Eurasian Mid–High Latitude in Winter and Its Association with the Eurasian Teleconnection Pattern
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发表时间：
2014
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通讯作者：
Yan Shuangya
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作者：
Yan Shuangya
利用美国国家环境预报中心-国家大气研究中心（NCEP-NCAR）再分析资料，分析了冬季欧亚中高纬低频振荡（LFO）的传播特征及其与欧亚背景大气环流的年际联系。结果表明，低频环流的优势期为10-30天，东南传播明显。10-30天低频振荡的纬向和纬向平均速度分别约为3.4纬/d和15纬/d。进一步分析表明，低频振荡的年际变化与欧亚地区的遥相关型（EU）密切相关。我们将EU的负（正）位相定义为当乌拉尔地区的高压脊和东亚及西北欧的低压槽弱（强）于平均年份时，EU指数小于（大于）零。当对流层中上层EU处于负位相时，对流层低层西伯利亚高压偏弱。这些因素导致欧亚地区大尺度纬向环流和纬向环流减弱，不利于低涡在欧亚中高纬的传播，反之亦然。
The propagating characteristics of low-frequency oscillation(LFO) over Eurasian mid–high latitude in boreal winter and its interannual link with the Eurasian background atmospheric circulation are analyzed by using the National Centers for Environment Prediction–National Center for Atmospheric Research(NCEP–NCAR) reanalysis data. The results show 10–30 days dominant periods of low-frequency circulation and clear southeast propagation. The meridional and zonal mean speeds of the 10–30-day LFO are about 3.4 latitudes/d and 15 longitudes/d, respectively. Further analysis shows that the interannual variation of the LFO is closely related to the Eurasian teleconnection pattern(EU). We define the negative(positive) phase of EU as conditions occurring when the ridge over the Ural area and the troughs over East Asia and northwestern European are weaker(stronger) than that in an average year such that the EU index is less than(greater than) zero. When the EU at the middle and upper troposphere is in a negative phase, the Siberian high at the low troposphere is weaker. These factors lead to weaker large-scale meridional circulation and dominant zonal circulation over the Eurasian region, which is not conducive to the propagation of the LFO over the Eurasian mid–high latitude or vice versa.