The Past Millennium Preliminary Reconstruction Of The Surface Temperature Sequences And Sequence Analysis

Twenty seven tree-ring chronologies from 7 individual sites in western and northeastern China, which have been proved good in quality and being capable of indicating seasonal temperature variation at regional scale, are collected and used to reconstruct regional annual mean temperature series. Combined with the winter-half-year temperature series in eastern China reconstructed by Ge et al. (2003) using historical documents, area-averaged annual mean temperature anomalies with time resolutions of 10-30 years over the past 1000 years for entire China are also reconstructed.Wavelet analysis is made for the regional series, which indicates significant centennial cycle, though the periodic signs tend to be weaker after A.D. 1500. Variability and amplitudes of cold-warm changes in China over the past 1000 years are discussed as well. Choosing A.D. 1951-1980 as climate reference period, annual mean temperature of China is generally wanner from A.D. 1000 to 1310 with a relatively cool episode in 13th century, and it is significantly colder from A.D. 1310 to 1910 with minimum anomalies occurring in 15th, 17th and 19th century respectively. Modern warm period beginning from the end of 19th century looks unusual in terms of the 1000 year variation of annual mean temperature, but it is not significantly warmer than the earlier warm period or Medieval Warm Period (MWP).Some differences between the series of western and eastern China have been detected, and there seems no significant warming during the MWP in the western temperature series. We also compare the present temperature series with those obtained by other researchers.