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Abstract
This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal
winter and their association with the Arctic Oscillation/North Atlantic Oscillation (AO/NAO). In January,
the relationship between the Ural blocking high (UR) and the AO index is statistically significant. The UR
tends to occur more frequently and with greater strength during negative AO periods. Some strong URs
also occur during positive AO phases (positive UR-AO events), as in January 2008. This paper discusses the
characteristics of atmospheric circulation in the cases of positive UR-AO events and contrast cases (negative
UR-AO events). The eastward extending of the Icelandic Low (IL) center and the associated NAO dipole
anomaly pattern in the upstream region may play a more important role for the UR-AO events. When
the center of the IL shifts eastward to 30°W, the amplitude of zonal wavenumber 2 (wavenumber 3) is
intensified in the positive (negative) UR-AO events, which favors positive (negative) height anomalies over
the Urals. Further analyses indicate that the intensified zonal wind in high latitudes and weakened zonal
wind in midlatitudes over the North Atlantic Ocean render the eastward shift of the IL and the NAO dipole
anomaly pattern. The Ural blocking in January 2008 bears similar characteristics to the positive UR-AO
events.
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Citation
LI Chao, ZHANG Qingyun, JI Liren, PENG Jingbei. 2012: Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter. Journal of Meteorological Research, 26(2): 163-175. DOI: 10.1007/s13351-012-0203-3
LI Chao, ZHANG Qingyun, JI Liren, PENG Jingbei. 2012: Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter. Journal of Meteorological Research, 26(2): 163-175. DOI: 10.1007/s13351-012-0203-3
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LI Chao, ZHANG Qingyun, JI Liren, PENG Jingbei. 2012: Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter. Journal of Meteorological Research, 26(2): 163-175. DOI: 10.1007/s13351-012-0203-3
LI Chao, ZHANG Qingyun, JI Liren, PENG Jingbei. 2012: Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter. Journal of Meteorological Research, 26(2): 163-175. DOI: 10.1007/s13351-012-0203-3
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