An Urban-Scale Ensemble for WesCon

Abstract: The Wessex Convection Experiment (WesCon) was a UK field campaign conducted during summer 2023 concentrating on understanding dynamical aspects of convection to provide observational data to develop next generation kilometre-scale and urban-scale models. During the campaign, extended evaluation of a variable resolution 300 m Wessex Model (the “WMV”) was conducted, running as an ensemble nested inside the Met Office operational UK 2.2km grid length ensemble (MOGREPS-UK). Results will be presented that show overall, the WMV looks promising for high-impact convective events as it is better able to represent the organisation of convection into lines or larger storms whereas MOGREPS-UK tends to simulate isolated, circular storms. This often leads to more reliable probabilities of heavy rainfall in the WMV ensemble compared to MOGREPS-UK. However, there is still an issue with the WMV producing too many small precipitating showers in situations where there should only be shallow clouds. This is thought to be a result of shallow clouds getting too deep in the model and precipitating erroneously.  

Biography: Kirsty works in the Urban-scale Modelling group at MetOffice@Reading based at the University of Reading. Kirsty's work is focused on the representation of convection in high resolution models (grid lengths in the range 1 km – 100m). The aim of this work is to determine the best configuration for future operational models. An important aspect of this work is validating the Unified Model against observations obtained during field campaigns such as WesCon. Kirsty joined the Met Office in March 2013. Prior to this Kirsty completed her PhD in ocean waves and air-sea interactions at the University of Reading in 2008. Kirsty then went on to do post-doctoral work at the University of Reading, focusing on the initiation of convection over orography in convective-scale ensembles.