大气中二氧化碳的氧同位素的年间变化是由厄尔尼诺驱动的
Lisa R Welp1, Ralph F Keeling, Harro A J Meijer
1Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0244, USA. lwelp@ucsd.edu
Nature
|September 30, 2011
概括
大气中二氧化碳 (CO2) 的稳定同位素比率显示出与厄尔尼诺/南方振荡有很强的联系. 这种联系有助于改进植物和海洋对全球碳吸收的估计,这表明CO2循环比以前认为的要快.
科学领域:
- 大气化学和生物地球化学循环.
- 同位素地质化学 同位素地质化学.
- 气候科学及其对碳循环的影响.
背景情况:
- 监测大气中的CO2稳定同位素比率 ((18) O/ ((16) O和 (13) C/ ((12) C),以了解全球碳循环.
- 由于碳和水循环的影响,解释CO2中的氧同位素变化是复杂的.
- 之前的研究集中在20世纪90年代降低 (18) O/(16) O比率,将其归因于诸如土壤呼吸,作物变化和环境条件等因素.
研究的目的:
- 从斯克里普斯海洋学研究所的全球水瓶网络中分析了30年的 (18) O/(16) O大气CO2数据.
- 研究大气中二氧化碳二氧化同位素的年间变化与气候模式,特别是厄尔尼诺/南方振荡 (ENSO) 之间的关系.
- 使用与ENSO相关的同位素信号来限制全球初级生产总值 (GPP) 的估计.
主要方法:
- 采用了30年的大气二氧化碳 (CO2) (18) O/{16) O比率数据集,这些数据来源于全球式采样网络.
- 与ENSO事件以及热带降雨和植物水的相关变化相关联的年间同位素变化.
- 在同位素记录中分析ENSO异常的衰变时间,以推断CO2循环时间.
主要成果:
- 在大气中CO2的年间变化和厄尔尼诺/南方振荡之间发现了强烈的相关性.
- 热带湿度再分配的ENSO驱动的变化似乎影响了 (18) O/(16) O的降水和植物水的比率,然后转移到大气中的CO2).
- 从ENSO事件中观察到的快速恢复表明,生物圈,海洋和大气之间的CO2循环时间比以前估计的要短.
结论:
- 厄尔尼诺/南方振荡通过其对水循环和生物圈-大气交换的影响,显著影响大气中的CO2同位素组成.
- 目前估计的全球初级生产总值 (GPP) 可能被低估;建议修订的GPP为150-175 Pg C yr.
- 这一修订的GPP估计为评估全球生物圈碳循环模型提供了一个新的基准.
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