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全球大洋深海有孔虫碳同位素(δ13C)记录中广泛发现40万年周期,这一周期可能与偏心率长周期的轨道驱动有关.1.6 Ma以来,δ13C的这一长周期拉长到50万年,且重值期不再与偏心率低值对应.目前对δ13C 40万年周期的成因及其周期拉长的机制还不明确.这里使用了包含9个箱体的箱式模型,用于研究热带过程与冰盖相互作用及其对大洋碳循环的影响.模拟结果显示当北半球高纬海区海冰迅速增大时冰盖迅速融化,进入冰消期,而当海冰快速消失后,冰盖则重新缓慢增长.冰盖变化具有冰期长,间冰期短的非对称形态.在季节性太阳辐射量的驱动下冰盖变化具有10万年冰期-间冰期旋回.当冰盖融化速率受北半球高纬夏季太阳辐射量控制时,冰盖变化的岁差周期明显加强,相位与地质记录一致,说明轨道驱动可以通过非线性相位锁定机制使冰盖变化与其在相位上保持一致.海冰的阻隔效应使大气中CO2在冰消期时增多.冰期时大洋环流减弱使大气中CO2逐渐减少.当模型只有ETP驱动的风化作用而不考虑冰盖变化时,模拟的δ13C记录显示极强的40万年周期,体现了大洋碳储库对热带风化过程的响应.当同时考虑冰盖变化和风化作用时,模拟的δ13C结果中40万年周期减弱而10万年周期加强,并且40万年周期上碳储库与偏心率的相位与不考虑冰盖变化时的相位也存在差异,反映了冰盖变化引起的洋流改组压制了大洋碳循环对热带过程的响应.
The 40-million-year period is widely found in the records of the global oceanic deep-sea foraminiferal carbon isotopes (δ13C), which may be related to long-period orbital orbital drive of eccentricity. Since 1.6 Ma, the long period of δ13C has been extended to 500,000 years , And the reevaluation period no longer corresponds to the low eccentricity value.At present, the mechanism of the δ13C 40 000-year period and the mechanism of its periodic elongation are unclear. A box model with 9 boxes is used for research The interaction of tropical processes with ice sheet and its effect on the carbon cycle of the ocean. The simulation results show that when the sea ice rapidly increases in the high latitude northern hemisphere, the ice sheet melts rapidly and enters the ice elimination period. When the ice quickly disappears, The ice cover changes slowly with asymmetry of ice age and short interglacial period.The change of ice cover has a period of 100,000-year glacial-interglacial cycles driven by seasonal solar radiation.When the melting rate of ice cover is affected by the high During summer solar radiation control, the precession cycle of ice cover was significantly enhanced, and the phase was consistent with the geological record, indicating that orbital driving can make the ice cover change in phase with the non-linear phase-locking mechanism. The effect causes the atmospheric CO2 to increase during the depletion of ice and the decrease of the atmospheric CO2 during the ice age reduces the CO2 in the atmosphere.When the model has only ETP-driven weathering without considering changes in ice cover, the simulated δ13C record shows a strong 400,000 The annual cycle reflects the response of the oceanic carbon reservoir to the tropical weathering process.When both the ice cap change and weathering are taken into account, the simulated δ13C results are weakened by 400000 cycles and strengthened by 100000 cycles, and on the 400000 cycles The phase of carbon reservoir and eccentricity is also different from the phase without considering the change of ice cover, reflecting the ocean current shuffling caused by the change of ice sheet, which suppresses the response of oceanic carbon cycle to tropical processes.