AeroCom Multi-Model Analysis of Two-Decadal Trends and Interannual Variability of CO and Aerosols in the Upper Troposphere and Their Connections to Surface Emissions and Asian Summer Monsoon Dynamical Processes

We report results on interannual variabilities and two-decadal trends of CO and aerosols in the upper troposphere (UT) from multiple global model simulations in the AeroCom UTLS/ACAM experiment, which involves nine global model simulations of aerosols and related species from 2000-2019. Here, we will a) diagnose the interannual variabilities of Asian summer monsoon convective transport efficiency aerosol removal efficiency using a suite of tracers that are implemented by all models, and b) assess the CO and aerosol trends in the past two-decades in the UT and their connections to the surface emission trends in South Asia and East Asia. We will also discuss the inter-model differences in transport and removal processes and the resulting uncertainties in attributing the cause of the variabilities of aerosols and CO in the UT.