An Observed Connection Between Wintertime Temperature Anomalies over Northwest China and Weather Regime Transitions in North Atlantic

• Published in: Acta meteorologica Sinica Vol. 29; no. 2; pp. 201 - 213
• Main Author: 李超 张庆云
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Meteorological Society 01.04.2015
• Subjects: Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Earth and Environmental Science; Earth Sciences; Geophysics and Environmental Physics; Marine; Meteorology; 中国西北部; 乌拉尔山脉; 冬季; 北大西洋; 天气尺度; 斯堪的纳维亚; 温度异常; 状态转换; AN, North Atlantic; Russia, Ural Mts; AN, North Atlantic, North Atlantic Oscillation; Eurasia, Ural Mts; China, People's Rep; low temperature in Northwest China; synoptic evolution; North Atlantic Oscillation; weather regime
• ISSN: 2095-6037; 0894-0525; 2198-0934; 2191-4788
• DOI: 10.1007/s13351-015-4066-2

In this study, the association between wintertime temperature anomalies over Northwest China and the weather regime transitions in North Atlantic on synoptic scale is analyzed by using observational surface air temperature（SAT） data and atmospheric reanalysis data. Daily SAT anomaly and duration time are used in order to define SAT anomaly cases. Differences with regard to the circulation anomalies over the Ural Mountains and the upstream North Atlantic area are evident. It is found that the colder than normal SAT is caused by the enhanced Ural high and associated southward flow over Northwest China. Time-lagged composites reveal possible connections between the SAT anomalies and the different development phases of the North Atlantic Oscillation（NAO）. The Ural highs tend to be strengthened during the negative phase of NAO（NAO-） to Atlantic ridge transition, which are closely related to the downstream-propagating Rossby wave activity. The opposite circulation patterns are observed in the warm SAT cases. A cyclonic circulation anomaly is distinctly enhanced over the Urals during the positive phase of NAO（NAO＋） to Scandinavian blocking transition, which would cause warmer SAT over Northwest China. Further analyses suggest that the intensified zonal wind over North Atlantic would favor the NAO- to Atlantic ridge transition, while the weakened zonal wind may be responsible for the transition between NAO＋ and Scandinavian blocking.