近2 Ma BP以来地球轨道参数周期上全球海平面变化机制

Mechanism of Sea Level Change at the Earth Orbital Parameter Cycles during the Last 2 Ma BP

海平面的变化往往对区域生态环境、社会经济造成严重影响.通过对全球相对海平面变化(relative sea level,简称RSL)记录的再分析结果,合成了近2 Ma BP以来的全球RSL变化记录,分析了合成RSL记录对原始RSL记录数理特征的继承性,并基于频谱、滤波等数理分析验证了合成RSL记录的合理性.在此基础上,讨论了合成RSL与大气CO_2浓度、中高纬度海域表层海水温度(sea surface temperature,简称SST)、全球大洋底栖氧同位素(δ^(18)O_B)等参数指标间的相关性,结果显示:(1)合成RSL不仅与原始RSL记录的变化趋势基本一致,继承了原始RSL记录对全球气候变化的响应特征,而且显示出合成RSL记录对地球轨道参数周期变化响应明显;(2)近2 Ma BP以来,在冰期-间冰期旋回中,合成RSL与δ^(18)O_B变化呈良好的负相关,相关系数r平均值可以达到约0.81,高于合成RSL与大气CO_2浓度及中高纬度海域SST变化的相关系数;(3)在地球轨道参数周期上,合成RSL与极地冰盖体积(δ^(18)O_B)的变化几乎同时,在偏心率周期上,合成RSL落后于SST和大气CO_2浓度变化;在斜率周期上,合成RSL落后于SST变化而领先于大气CO_2浓度变化.推测这些变化的诱导因素可能是在太阳辐射量改变的前提下,大气CO_2浓度及大洋SST变化对极地冰盖体积产生了差异影响,进而引起海平面发生变化.

Sea level change usually has great impact on global（or regional）ecological environment and social economy.Based on the published records of relative sea level（RSL）,one new stacked RSL is reconstructed in this paper,and the correlations between the new stacked RSL and original records are analyzed.In addition,the reliability and rationality of the new stacked RSL are tested and verified respectively by Spectrum and Filtering analysis.Furthermore,the evolutionary history and correlations between the stacked RSL and atmospheric CO2 concentration,sea surface temperature（SST）in middle-high latitudinal oceans and benthic oxygen isotope（δ18OB）record are separately discussed in detail.The results show that：（1）the new stacked RSL has the similar change trend to the original RSL records during the last 2 Ma BP,and the correlation coefficients are all nearly 0.9.Meanwhile,the new stacked RSL also responds well to the global climate change events at the earth orbital parameter cycles;（2）The new stacked RSL and LR04-δ18OBhave high negative correlation in glacial-interglacial cycles during the last 2 Ma BP,with the correlation coefficient of about 0.81,which is much higher than those of the new stacked RSL with SST and atmospheric CO2concentration;（3）Based on the cross-spectral analytical results between the new stacked RSL and CO2,SST and δ18OB,individually,the new stacked RSL is nearly in phase with δ18OB,and both lags SST and CO2 at the eccentricity band,and lags SST but leads CO2 at the obliquity band.It is concluded that the polar ice sheet volume was influenced by changes of SST and atmospheric CO2 concentration,which might be caused by the change of solar insolation and finally influenced the sea level change at the earth orbital parameter cycles.