How Does Coldwave Frequency in China Respond to a Warming Climate? (Published in Climate Dynamics)
【摘要】：Under the background of a warming climate, regional climate responses may be different from place to place. How cold extreme events in China respond is still an open question. This study investigates responses of coldwave frequency (CWF) in China from observation and modeling perspectives. Observational evidences show that CWF significantly reduces across China during the warm period (1978 2009) in comparison with that during the cold period (1957 1977), concurrent with extreme value centers located in northern China during 1957 1977 and southern China during 1978 2009. The Empirical Orthogonal Function (EOF) leading mode of CWF in the cold period is also dominant by an extreme value center prevailing over northern China, while the center exhibits a southward shift in the warm period. A seven-member multi-model ensemble (MME) from Coupled Model Intercomparison Project#3 (CMIP3) shows that southern China tends to experience more coldwaves than northern China in the 21 st century (2045 2064 and 2080 2099) under the global warming A1B forcing (with atmospheric CO 2 concentration of 720 ppm). This feature can also be seen in the leading EOF mode of MME. These results indicate that the primary response of CWF to a warming climate may be the southward shift of the maximum loading center. The enhanced western Pacific Subtropical High and weakened Siberian High during 1978 2009 may result in anomalous southerlies which bring warm and wet air to southern China. Meanwhile cold and dry air is transported from the north via a "northwest pathway" to southern China. Under the joint action of these two air masses, coldwaves may easily generate in southern China as observed in recent extreme cold events in this region.