Abstract. Upper tropospheric outflow is analysed in cloud resolving large eddy simulations. Thereby, the role of convective organisation, latent heating and other factors in upper tropospheric divergent outflow variability from deep convection is diagnosed using a set of about 100 large eddy simulations, because the outflows are thought to be an important feedback from (organised) to large scale atmospheric flows: perturbations in those outflows may sometimes propagate into larger scale perturbations. Upper tropospheric divergence is found to be controlled by net latent heating and convective organisation. At low precipitation rates isolated convective cells have a stronger mass divergence than squall lines. The squall line divergence is the weakest (relative to the net latent heating) when the outflow is purely 2D, in case of an infinite length squall line. At high precipitation rates the mass divergence discrepancy between the various modes of convection reduces. Hence, overall the magnitude of divergent outflow is explained by the latent heating and the dimensionality of the outflow, which together create a non-linear relation.

Abstract. The sensitivity of upper tropospheric and lower stratospheric convective outflows and related divergence fields is analysed using an ensemble of cloud resolving model (CM1) simulations in LES-mode including various physically manipulated simulations for three different convective systems initialized with an idealized trigger. The main goal of this study is to assess to what extend the divergence field depends on cloud microphysical processes, the mode of convection and on the processes of convective momentum transport and moist static energy redistribution. We find that latent heat release (representing the microphysical uncertainty) plays an essential role by explaining much of magnitude of the divergence field that will be formed. Convective organisation explains another important fraction of the variability in the divergence field that is formed by a convective system and behaves non-linearly, likely partly via condensation and subsequent (re-)evaporation/sublimation. The detrainment of stratospheric air also shows large sensitivity among the experiments.

The southern Germany and EU-nest domains are specified in Figure S1. Synoptic configurationA plot providing further information on the investigated case, based on classical 850 and 500 hPa variables, is provided in Figure S2.

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