Sensitivity of simulated warm conveyor belt associated with an extratropical cyclone to model resolution and treatment of cloud processes - a NAWDEX case study

Previous work showed that simulations of extratropical cyclones and their intensity are significantly impacted by model resolution. This might be explained by the impact of resolution on cloud diabatic processes occurring within the warm conveyor belt (WCB), as these are linked to the strength of cyclones. To investigate this link, we move gradually from very coarse (80km) to very fine resolution (2.5km) simulations and study if there is a systematic impact of resolution on the simulated WCB processes. For this purpose, we analyse ICON simulations in a regional North Atlatnic setup for a specific case from the NAWDEX campaign -  cyclone Vladiana - that occurred on 23^rd September, 2016. Furthermore, we compare simulations with 1- and 2- moment cloud microphysics and with explicit and parametrized convection. From these simulations WCB trajectories are calculated over 48 hours by means of the Lagranto tool and 1-hourly model output to sample cloud diabatic processes within the WCB. We find a systematic increase in the number of WCB trajectories with finer resolution, which also ascent higher. Moreover, the fine-resolution simulations show a new class of anticyclonic trajectories that is absent in the low-resolution simulations. This effect becomes more pronounced when convection is represented explicitly, but is not strongly affected by the treatment of cloud microphysics. We diagnose the impact of increasing resolution on WCB in terms of changes in processes like updraft velocity, diabatic heating and modification of potential vorticity by total diabatic heating and individual diabatic processes.