[A-AS02] Weather, Climate, and Environmental Science Studies using High-Performance Computing

[AAS02-P07] Estimation of Interhemispheric Transport of Carbon Dioxide Related to Eddies based on Model Simulations

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

Keywords:carbon dioxide, model simulation, atmospheric transport

Atmospheric transport of carbon dioxide (CO2) between hemispheres, interhemispheric transport, has been documented to be generated by multiple mechanisms (Erukhimova and Bowman, 2006; Webster and Holton, 1982; Staudt et al., 2001). Despite the asymmetry in anthropogenic and natural emissions of CO2, mainly in the Northern Hemisphere, atmospheric CO2 distributions in the upper troposphere are more homogeneous because of the interhemispheric transport. Reflecting changes in interhemispheric transport, it has been shown that interannual changes in atmospheric CO2 gradient between the Northern and Southern hemispheres are related to eddy transport, which is associated with westerly ducts in 2009-10 (Francey and Frederiksen, 2016). However, the independent contribution of eddy transport associated with the westerly ducts is still not clear. Complementary to previous studies, we focus on estimating the contribution of eddy transport associated with the westerly duct and their impact on interannual changes of atmospheric CO2 gradient. In this study, we simulated atmospheric CO2 using the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) with CO2 fluxes from NISMON-CO2-2022 (Niwa et al., 2022). The westerly ducts represented by the relatively weak strength of westerly winds during 2009 were captured by the simulation. Furthermore, we compared the simulated interannual changes of the atmospheric CO2 gradient with the in situ ground observations.