[A-CG32] Global Carbon Cycle Observation and Analysis

[ACG32-03] Evaluation of MIROC4-ACTM reanalysis of GHGs concentrations using aircraft

*Jagat Bisht¹, Prabir Patra¹, Naveen Chandra¹, Sergey Gromov², Taku Umezawa³, Andreas Zahn⁴, cARL A. M. Brenninkmeijer⁵ (1.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan, 2.Max Planck Institute for Chemistry, Mainz, Germany, 3.National Institute for Environmental Studies, Tsukuba, Japan, 4.Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research, Karlsruhe, Germany, 5.Max Planck Institute for Chemistry, Air Chemistry Division, Mainz, Germany)

Keywords:MIROC4-ACTM, CONTRAIL, CARIBIC

Using the “Atmospheric Chemistry Transport Model” being part of the “Model for Interdisciplinary Research On Climate Earth System Model, version 4” (MIROC4-ACTM), simulations of several important greenhouse gases, such as CH₄, CO₂, SF₆, and N₂O, have been conducted using optimized emissions by inverse modelling of surface measurements for the period 1996-2016 (referred to as “reanalysis data”). Aircraft observations, conducted on board passenger aircraft (projects: CARIBIC and CONTRAIL) over diverse latitude and longitude regions offer independent constraints for evaluating the quality of reanalysis data. MIROC4-ACTM captures the variations in CO₂ and SF₆ observed by CARIBIC and CONTRAIL very well, with a correlation coefficient of above 0.96 and a slope of 0.92 at all atmospheric conditions. However, for CH₄ and N₂O the agreement was worse, with correlation coefficients (slopes) between CONTRAIL observations and model simulations of 0.80(0.49)-0.87(0.66) and 0.74(0.55)-0.77(0.75), respectively, at 0-140^oE and poleward of 40^oN. Further south, that is between 30^oS-40^oN latitude (for the Tokyo-Australia flights), the correlation coefficients (slopes) was 0.76(0.83)-0.88(0.89) and 0.92(0.87)-0.98(1.05), respectively. Similarly, the agreement with the CARIBIC observations was moderate for CH₄ and N₂O, with correlation coefficients (slopes) of 0.81(0.55) and 0.88(0.65), respectively.