Changing North American Circulation Pattern in the Last 100 Years.

More climate extreme events have occurred in recent years, including the continual development of extreme drought in California, the severe cold winters in the eastern U.S. since 2014, 2015 Washington drought, and excessive wildfire events over Alaska in 2015. These events have been linked to various continental to large-scale circulation anomalies across North America. Interestingly, dominant circulation pattern affecting North America, especially in the western NA during winter time has been changing. In this work, we attempt to depict how this circulation pattern has been changing and potential causes. Particularly, how the man-made global warming can be linked to such changes will be discussed in comparison to natural climate variabilities.