The historical climate trend resulted in changed vertical transport patterns in climate model simulations

Abstract

Convective transport leads to a rapid vertical redistribution of tracers. This has a major influence on the composition of the upper troposphere (UT), a highly climate-sensitive region. It is not yet clear how the convective transport is affected by climate change. In this study, we applied a new tool, the so-called convective exchange matrix, in historical simulations with the chemistry-climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) to investigate the trends in convective transport. The simulated deep convection is penetrating higher but occurs less frequently from 2011 to 2020 than from 1980 to 1989. The increase in the vertical extent of convection is highly correlated with a rise in the tropopause height. The upward transport of air mass increased on average to height levels of 130 hPa and above, but convection transported material less efficiently to the upper troposphere in general from 2011 to 2020 in comparison to the 1980s. These findings give rise to new opportunities to investigate long-term simulations performed by EMAC with regard to the effects of convective transport. Furthermore, they might provide a first insight into the trends in atmospheric convective transport due to changing atmospheric conditions and might serve as an estimate for the convective feedback to climate change.