QING BAO

LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

YIMIN LIU AND GUOXIONG WU

LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

BIN WANG

Department of Meteorology, and International Pacific Research Center, University of Hawai at Manoa, Honolulu, Hawaii

Anomalous warming occurred over the Tibetan Plateau (TP) before and during the disastrous freezing rain and heavy snowhitting central and southernChina in January 2008. The relationship between the TPwarming and this extreme event is investigated with an atmospheric general circulation model. Two perpetual runs were performed. One is forced by the climatological mean sea surface temperatures in January as a control run; and the other has the same model setting as the control run except with an anomalous warming over the TP that mimics the observed temperature anomaly. The numerical results demonstrate that the TP warming induces favorable circulation conditions for the occurrence of this extreme event, which include the deepened lower-level South Asian trough, the enhanced lower-level southwesterly moisture transport in centralsouthern China, the lower-level cyclonic shear in the southerly flow over southeastern China, and the intensifiedMiddle East jet stream in the middle and upper troposphere.Moreover, the anomalous TP warming results in a remarkable cold anomaly near the surface and a warm anomaly aloft over central China, forming a stable stratified inversion layer that favors the formation of the persistent freezing rain. The possible physical linkages between the TP warming and the relevant resultant circulation anomalies are proposed. The potential reason of the anomalous TP warming during the 2007–08 winter is also discussed.

Corresponding author address: Dr. Jing Yang, State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, 100875, China. E-mail: yangjing@bnu.edu.cn