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为调查树轮稳定氧同位素在西藏南部的气候应用潜力,选择了西藏亚东县三个铁杉(Tsuga chinesis Pritz.)样本进行分析。其中两个样本表现出长期的稳定氧同位素下降趋势,而另一个表现出增高趋势,且三者相关性很低。当对三条稳定氧同位素序列进行一阶差处理之后,它们的相关关系有了非常显著的提高,表现出很好的一致性(p<0.0001)。无论是原始还是一阶差树轮稳定氧同位素序列,它们都与夏季相对湿度和降水反相关,而与温度正相关,然而方差解释量未能达到古气候重建的最低要求。周期分析发现亚东树轮稳定氧同位素序列仅存在4.657年的显著周期,可能与ENSO活动有关,进一步研究显示1978年之前上年冬天到当年夏天的赤道中东太平洋海表温度对亚东树轮稳定氧同位素有显著影响(p<0.01),而在1978年之后则无任何影响,20世纪70年代末期的全球气候突变改变了ENSO对该地树轮稳定氧同位素的影响。
In order to investigate the climatic potential of tree-ring stable oxygen isotopes in southern Tibet, three samples of Tsuga chinesis Pritz. Were selected for analysis. Two of the samples showed long-term stable oxygen isotope declines, while the other showed an increasing trend with a low correlation. When the three stable oxygen isotopes were first order-difference treated, their correlation was significantly improved and showed good agreement (p <0.0001). Both the primary and the first order tree-ring stable oxygen isotope sequences, which are inversely correlated with summer relative humidity and precipitation, are positively correlated with temperature, however, the variance explained fails to meet the minimum requirements of paleoclimate reconstruction. Periodic analysis showed that there was only a significant period of 4.657 years for the stable oxygen isotope sequence of Yadong Tree Stratum, which may be related to ENSO activities. Further studies showed that the temperature in the equatorial Middle East and East Pacific before 1978 was stable to Yadong Tree Stump Oxygen isotopes (p <0.01), but no effect after 1978. The global climate change in the late 1970s changed the effect of ENSO on the stable oxygen isotope of tree rings in this region.