Changes in the convective transport into the upper troposphere due to climate change

The atmospheric temperature and moisture profiles have changed given the rapid increases in the sea surface temperature in the past decades. This has implications for the stability of the atmosphere and therefore for the frequency, intensity and other characteristics of atmospheric moist convection and convective transport of water vapour and trace species. The latter is of high relevance to the composition of the upper troposphere and lower stratosphere.
We performed a historical simulation with the global chemistry climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) from 1979 to 2020 and investigated the changes in convective properties and transport. Within EMAC, the convective exchange matrix is applied to quantify and track the convective transport. This tool connects the transport of air masses between all model levels due to convection and enables the analysis of convective transport features and their changes disentangled from other processes.
Deep convection is reaching higher in the decade from 2011 to 2020 in comparison to 1980 to 1989. This is strongly correlated with an increase in the tropopause height. Thereby, the convective mass fluxes increased in the upper troposphere, but the overall strength of the convection did not change. Deep convection occurs less frequently in the more recent period. This leads in total to a decrease in the transport from the boundary air to the upper troposphere on average from 2011 to 2020 compared to the reference period at the beginning of the simulation time. We will present these trends and their dependence on the choice of the convection parameterisation and the nudging of the meteorological conditions.