11:30 AM - 11:45 AM
[ACG35-04] MIROC4.0 based atmospheric chemistry-transport model (MIROC4-ACTM): Improved dynamical features for greenhouse gases modelling
Keywords:Greenhouse gases modelling, Interhemispheric transport, Stratosphere-troposphere exchange
The MIROC4-ACTM produces “age-of-air” up to about 5 years in the tropical upper stratosphere (at about 1 hPa) and 6 years in the polar middle stratosphere (at about 10 hPa). Our comparisons of MIROC4-ACTM with the simulations using pure sigma-pressure vertical coordinate (AGCM5.7b-ACTM) suggest that the former is characterized by slower convective transport in the troposphere and much lesser meridional diffusive transport in the stratosphere. The MIROC4-ACTM simulations produce better agreement with SF6 observations at the surface sites and aircraft campaigns (e.g., HIPPO), compared to those using the ACGM5.7b-ACTM.
The MIROC4-ACTM is being developed for inverse modelling of long-lived gases for reducing bias in estimated emissions caused by uncertainties in model transport. These advancement in MIROC4-ACTM system also produces key improvements that are required for ingesting columnar CO2 and CH4 measurements from Greenhouse gases observing satellite (GOSAT) and other remote sensing instruments in an inverse modelling system. The stratospheric transport was not a cause of major concerns for utilizing in situ observations from the tropospheric altitudes in inversion systems, which however is not the case for columnar data.
Acknowledgements. PKP appreciate help from Kentato Ishijima in preparation of the JRA-55 meteorological fields for the hybrid coordinate system.