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A continuous record of surface temperature for the past 2650 years was obtained in an earlier study from a Beijing stalagmite based on sedimentary layer counting and thickness measurements.Singular spectrum analysis,multi-taper and wavelet spectral analyses are used in this study to identify decadal-scale signals and their origins in this record.Besides long-term cycles of solar origin identified in earlier studies,this record contains cycles that dominate temperature with periods of 102-70,66-50,31,25-22,19,15,12 and 9 years.The 102-70,25-22,12 and 9 year cycles are attributable to solar variation,while the others are likely to be related to low-latitude ocean forcing.These results suggest that century-scale changes in the Beijing summer temperature over the past 2650 years are primarily controlled by solar variation,while ocean-atmospheric interactions play a prominent role in modu-lating decadal-scale variability.
A continuous record of surface temperature for the past 2650 years was obtained in an earlier study from a Beijing stalagmite based on sedimentary layer counting and thickness measurements. Singular spectrum analysis, multi-taper and wavelet spectral analyzes are used in this study to identify decadal- scale signals and their origins in this record .esides long-term cycles of solar origin identified in earlier studies, this record contains cycles that dominate temperature with periods of 102-70, 66-50, 31, 25-22, 19, 15, 12 and 9 years. The 102-70, 25-22, 12 and 9 year cycles are attributable to solar variation, while the others are likely to be related to low-latitude ocean forcing. These results suggest that century-scale changes in the Beijing summer temperature over the past 2650 years are primarily controlled by solar variation, while ocean-atmospheric interactions play a prominent role in modu-lating decadal-scale variability.