科研之友
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摘要
The relationship between the El Nino/Southern Oscillation (ENSO), volcanic aerosol, and the carbon cycle has been characterized through analyses of atmospheric CO2, biogeochemical modeling and recently through inverse estimation. However, the studies to date contain weaknesses that make quantitative assessment of the relationship unreliable. Here we present a systematic quantification of the relationship between ENSO, volcanic aerosols and regional net carbon exchange using results from the TransCom Atmospheric CO2 Inversion Intercomparison and a simple 2-step regression method. A modified ENSO index (ENSO tau) is created by estimating the component of ENSO variability that is linearly uncorrelated to aerosol optical depth, and the relationships are estimated by performing correlation analysis with the TransCom 3 tropical terrestrial carbon flux estimates. Flux anomalies from the tropical land regions (Tropical America, Northern Africa, Tropical Asia) show statistically significant correlations with anomalies of ENSO tau, with carbon exchange lagging the ENSO tau by two to six months. Further analysis by season and warm phase/cold phase shows the ENSO tau warm phase explaining >70% of the variability in tropical net carbon exchange. Tropical Asia shows the largest response with positive carbon flux anomalies following two to three months behind the peak of the ENSO tau warm phase. Total tropical land carbon flux anomalies of +0.59 GtC/year result from a typical (one standard deviation) warm ENSO tau event and are consistent with estimates of carbon loss via tropical fire.
- 出版日期2012-3-23
