新论文介绍:The role of warm North Atlantic SST in the formation of positive height anomalies over the Ural Mountains during January 2008
[发布日期: 2014-12-31 浏览量 639]
The most severe snowstorm and freezing-rain event in the past 50 years hit central and southern China in January 2008. One of the main reasons for the anomalous climate event was the occurrence of atmospheric circulation anomalies over middle and high latitudes, particularly the persistent blocking that occurred over the Ural Mountains. Along with atmospheric anomalies, a strong La Ni~na event in the Paci¯c and warm sea surface temperature anomalies (SSTAs) in the North Atlantic were the most signi¯cant in the lower boundary. Since a brief analysis suggests that La Ni~na exerts no signi¯cant impact on the Urals, the key point of focus in this study is on the role of the warmer SSTAs in the North Atlantic. Based on an observational composite, North Atlantic SSTAs pattern when the height anomaly over the Urals is strongly positive is found similar to that in January 2008, but no signi¯cant SSTAs occurred elsewhere, such as the Paci¯c. Using an atmospheric general circulation model, ECHAM5, the impact of North Atlantic SSTAs on the extratropical atmosphere circulation in the event was investigated. The results show that the warm SSTAs strengthened the blocking high over the Urals, through anomalous transient eddies. The consistency between the study model and the observational composite indicates that the warm SSTAs in the North Atlantic were indeed an important factor in the formation of the snowstorm disaster of January 2008.