Sensitivity analysis of divergence and underlying processes around organised convection with a cloud resolving model

In this study we are trying to understand (limits of) predictability related to (organised) convection and its upscale error growth.

For that purpose we aim to analyse the impact of three convection driving and amplifying processes, namely latent heat release, redistribution of moist static energy and convective momentum transport on the development of the convective cells. Furthermore, we plan to investigate uncertainties in these processes on downward propagation of the flow and ensemble spread.

The first results to be presented regard an idealised and strongly organised case of splitting convective storms modeled at different resolutions and with some small adaptations in the model convective cloud resolving model CM1. Currently processed resolution experiments show that both the actual divergence field and the processes supected to underlie it exhibit some sensitivity to model resolution on the subkilometre scale (100-1000 m). We can also show that the upper tropospheric divergence can be directly related to the latent heat release, as it is located vertically above the major latent heat releases. Nevertheless, neither the vertical redistribution of moist static energy nor the convective momentum transport are negligible and all three impact the divergent outflow of the convective storm.