An Abrupt Increase of the Summer High Temperature Extremes across China in the mid 1990s

Based on the daily maximum surface air temperature dataset from 752 stations during 1958 to 2008 in China, we revealed that there is an abrupt increase of the number of days with high temperature extremes (HTEs, a HTE day is defined while the maximum temperature exceeds the 95% percentile) across China in the mid 1990s. Before this regime shift, the average number of HTE days is about 2.8 days per year during the period from the 1970s to the early 1990s, while it rocketed to about 7.7 days per year after the mid 1990s. We show that the significant HTE increasing occurs unanimously across the whole China after the regime shift. The observational evidences raise the possibility that this change of the HTE days is associated with large-scale circulation changes as well as the nonlinear behaviors of the high temperature events.