Influence of Prior Thermal State of Global Oceans on the Formation of the Disastrous Snow Storm in January 2008

The global ocean heat status prior to January 2008,when the disastrous snowstorm freezing climate event occurred in South China,was investigated,and the results suggest that the strong La Nia event in the tropical Pacific and the anonymous warmth in the extratropical North Atlantic are the most significant.Additionally,there is warmth in the central North Pacific and in the Nordic Sea where has less sea ice extension.By analyzing the observational data and conducting experiments in an atmospheric general circulation model(AGCM),we investigated the influence of the La Nia event.The results show that the strong La Nia can explain the colder climate and more precipitation than usual in South China,as well as the associated circulation anomalies like Mongolia Cold High.But,it cannot explain the enhancements of the west Pacific subtropical high and the blocking high over the Ural Mountains.Subsequently,we discussed the influence of the North Atlantic warmth using the results from a previous modeling study,and speculated that the warmth has played an important role for the maintenance of the persistent blocking over the Urals.Thus,it is concluded that the disastrous climate event happened in January 2008 may be resulted from the coordinate interaction of several factors including strong La Nia and North Atlantic warmth.