[A-AS05] Weather, Climate, and Environmental Science Studies using High-Performance Computing

[AAS05-P13] Estimates of Dynamical Processes Contributions to Interhemispheric CO₂ Transport

*Guangyu LIU¹, Hisashi Yashiro¹, Yosuke Niwa¹ (1.National Institute for Environmental Studies)

Keywords:atmospheric carbon dioxide, NICAM, atmospheric transport, large-scale eddy

Atmospheric transport processes play an important role in transporting atmospheric CO₂, influencing its global distribution. The interhemispheric gradient, the atmospheric CO₂ concentration difference between Mauna Loa observation (MLO) in the Northern Hemisphere (NH) and South Pole Observatory (SPO) in the Southern Hemisphere (SH), has been used to monitor interhemispheric transport [Francey and Frederiksen, 2016]. However, the quantitative contribution of individual atmospheric transport processes to interhemispheric transport remains insufficiently understood. To address this, we applied the continuity equation based on the transformed Eulerian mean (TEM) analysis [Andrews and McIntyre, 1976] to decompose atmospheric transport processes into Lagrangian mean and large-scale eddy transport. Our analysis primarily utilized atmospheric CO₂ datasets from NICAM (Nonhydrostatic Icosahedral Atmospheric Model) and CAMS (Copernicus Atmosphere Monitoring Service) for the period 2009–2019. We found that the time evolution of atmospheric transport processes corresponds with local changes in the upper troposphere at high latitudes of the SH, indicating their important roles on atmospheric CO₂ in this region. The contribution of individual atmospheric transport process to these local changes was captured, revealing a deficiency in eddy transport in the upper troposphere at low latitudes of the SH during periods of weak interhemispheric transport, providing estimates of eddy transport for comparison with the previous studies.