Spatiotemporal Characteristics Of Long-term Variation Of China's Winter Extreme Temperature

Based on the daily maximum temperature,minimum temperature and daily average temperature of 839 stations in China from 1961 to 2016 and reanalysis data sets as well,the long-term variations of winter extreme temperature in China were analyzed.The results show that in boreal winter both the extreme low temperature indices and the extreme high temperature indices at the majority of the stations in China exhibit a linear warming trend during the past decades.The warming trend in the extreme low temperature indices is more evident than that in the extreme high temperature indices.As for the interdecadal variation,the stations with the evident interdecadal variation of the winter extreme low temperature indices are mainly located in the north of Yangtze River,northern Xinjiang and the eastern Tibet Plateau.The days of cold day over north China is the only one extreme high temperature index that exhibit an evident interdecadal variation.Except for the distinct variation features of the extreme low temperature indices over the eastern Tibet plateau,the inter-decadal changes of the extreme low temperature indices in the north of the Yangtze River and northern Xinjiang and that of the extreme high temperature indices over north China are basically consistent after the year 1979.Accordingly,the period from 1979 to 2016 can be divided into three periods: pre-cold period(1979~1986),warm period(1987~2007)and post-cold period(2008~2016),to indicate the decadal periods when the extrem temperature indices experience evident variation.Further analysis reveals that the above consistent interdecadal variation of the extreme temperature over the three specific areas is associated with the interdecadal variation of the East Atlantic/West Russia teleconnection pattern,or of the frequency of the blocking high over Ural Mountains and of the amplitude of the planetary trough over East Asia.The circulation anomalies in the lower troposphere are not significant,indicating their marginal effects on the formation of the interdecadal variation of the extreme temperature indices.As revealed by the random sampling,the interdecadal variation of sea surface temperature in the western Pacific Ocean is consistent with the interdecadal variation of extreme temperature in winter in China.