The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Asymmetrical ocean carbon responses to La Niña and El Niño complicate global carbon budget estimation. Using multiple ocean CO₂ data products and an advanced ocean biogeochemical model, we identified significant asymmetries in ocean carbon magnitude, spatial distribution, and duration in the tropical Pacific Ocean. La Niña enhances ocean CO₂ outgassing (0.1-0.2 PgC/yr) with a broader poleward extension (15°S-15°N) for up to three years, while El Niño reduces outgassing (0.2-0.4 PgC/yr) with a narrower poleward extension (10°S-10°N) for up to one year. The ocean carbon anomaly shifts westward during La Niña and eastward during El Niño. These asymmetries are attributed to differing wind, precipitation, and ocean circulation anomalies between La Niña and El Niño. Additionally, the cumulative carbon flux remains slightly imbalanced, impacting the global ocean carbon sink closure. This study provides deeper insights into ocean carbon sink variability and highlights the need for enhanced monitoring of asymmetrical ocean carbon dynamics.
 

air-sea CO2 flux, ocean pCO2, asymmetry, tropical Pacific Ocean, La Niña, El Niño