ENSO与火山活动的共同作用对大气CO_2浓度年际变化的影响

The combined impacts of ENSO and volcanic eruptions on the interannual fluctuations of atmospheric CO_2

利用Mauna Loa和南极站点月均观测大气CO_2和δ^(13)C资料分析了大气CO_2浓度的年际变化特征,发现大气CO_2浓度年际变化与ENSO呈正相关而与火山喷发指数呈负相关。大规模火山喷发能够降低强ENSO对大气CO_2浓度的年际变化的影响,不仅与喷发强度有关,还与持续作用时间有关。ENSO与火山喷发共同影响大气CO_2浓度年际变化,而分析期间内的El Chichon和Pinatubo喷发后大气CO_2和δ^(13)C年际变化的差异则受ENSO和火山喷发的强度以及两者的相对起始时间的影响。δ^(13)C分析结合Keeling Plot计算表明,ENSO对大气CO_2浓度年际变化的影响主要通过影响陆地生态系统生产量的变化,而火山喷发对其影响则通过因温度降低和海洋施肥效应所引起的海洋吸收增加。

The interannual fluctuations of atmospheric CO 2(IFAC),as an important signal of global carbon cycle research,are closely related to the El Ni o-Southern Oscillation(ENSO).However,most studies regarding the impact of volcanic activities tend to focus merely on the post-Pinatubo eruption.By using monthly observational data of atmospheric CO 2 andδ13 C at Mauna Loa and the South Pole from the period of 1959 to 2008,this study analyzes the features of IFAC.A positive correlation is found between IFAC and ENSO,and a negative correlation between IFAC and the volcanic eruption index.The massive eruptions could reduce the impact from strong ENSO on IFAC.The influence of volcanic activities is related to the eruption intensity,as well as the magnitude of eruptions and duration of eruption effects.ENSO and volcanic eruption work together on the IFAC.During the analysis period,the diversity of atmospheric CO 2 andδ13 C variations after El Chichon and Pinatubo eruptions are related to the relative beginning time of both events.Usingδ13 C analysis and Keeling Plot calculation,ENSO exerts influence on IFAC through the changes of terrestrial biosphere,along with volcanic eruption,by means of oceanic uptake enhanced by the cooling and fertilization effects.