Day 1: Monday 23 June 2025
08:30 Arrival Coffee
09:00 Georgios Efstathiou: Welcome - workshop objectives.
09:10 Opening Talk: Katy Hill (Associate Director Foundation Science, Met Office) - Huw Lewis (Head Regional Model Evaluation & Development, Met Office): The Road to high-resolution NWP and importance of Hectometric NWP.
Session 1: Model Behaviour at Grey-Zone Resolutions | Chair: Dimitar Vlaykov
09:30 Rachel Honnert (Swedish Meteorological and Hydrological Institute) (Featured talk): From grey-zone of turbulence to AROME-500m.
10:00 Robert Beare (University of Exeter): The role of diffusion in boundary-layer turbulence simulation in the grey zone.
10:20 Didier Ricard (Météo-France): Counter-gradient structures in deep convective clouds and their representation in Numerical Weather Prediction models.
10:40 Coffee Break
11:00 Bowen Zhou (Nanjing University): Variations of Subgrid-Scale Turbulent Fluxes in the Dry Convective Boundary Layer at Gray Zone Resolutions.
11:20 Stephan de Roode (TU Delft): Momentum Transport in Turbulent Atmospheric Boundary Layers.
11:40 Paul Burns (Met Office): Filtering high-resolution UM simulations of idealised dry convective boundary layers to inform grey-zone turbulence modelling
12:00 Panel discussion with session speakers
12:45 - 14:00 Lunch
Session 2: Parametrisation approaches in the grey zone | Chair: Robert Beare
14:00 Peter Clark (University of Reading): 3DTE: A non-downgradient turbulence parametrization for the turbulent grey-zone.
14:20 Junshi Ito (Tohoku University): Greyzone parameterization developed by idealized large eddy simulations of back-building meso-scale convective systems.
14:40 Yuqi Bai (University of Reading): Implementation of dynamic filtering with grey-zone turbulent closures in a Numerical Weather Prediction Model: Evaluation in idealised cases.
15:00 Coffee Break
15:30 Robert Plant (University of Reading): Dynamic diagnoses of turbulent mixing lengths in shallow convection.
15:50 Jian Zhong (University of Greenwich): Implementation of a synthetic inflow turbulence generator in idealised WRF large eddy simulations under neutral atmospheric conditions.
16:10 Panel discussion with session speakers.
17:00 - 19:00 Poster Session (Conference rooms 1 & 2, Xfi Building)
18:00 — 19:00 Drinks and snacks reception (Conference rooms 1 & 2, Xfi Building)
Poster Contributions:
Lokahith Narendra Agasthya (Institute of Science and Technology, Austria): Moist Convective Scaling: Insights from DNS and CRM simulations.
Stephan de Roode (TU Delft): Dependency of mesoscale organization on grid anisotropy in large-eddy simulations of convective boundary layers at Gray Zone resolutions.
Yuhang Tong (University of Exeter): A Surface Layer Scheme for an Implicit Large Eddy Simulation Model.
Alison Stirling (Met Office): The ParaChute programme: An overview.
Daniela-Christin Littmann (German Weather Service - DWD): The Study of Near-Surface Interaction over Complex Terrain using Subhectrometric Simulations.
Robert Plant (University of Reading): A dynamic extension of the pragmatic blending scheme for scale-dependent sub-grid mixing.
Matthew Coburn (University of Southampton): Increasing high-fidelity modelling efficiency with automated setup and validation of methodologies.
Didier Ricard (Météo-France): C3IEL, the Cluster for Cloud evolution ClImatE and Lightning Mission to Study Convective Clouds at High Spatial and Temporal Resolution.
Chi-Chiu (Chris) Cheung (ClusterTech): Numerical weather prediction at 200 m local resolution based on the unstructured grid CPAS model.
Day 2: Tuesday 24 June 2025
Session 3: A Computational Fluid Dynamics perspective on the LES - RANS Grey Zone | Chair: Peter Clark
09:00 Arrival Coffee
09:30 Florian Menter (ANSYS) (Featured Talk): Hybrid RANS-LES Turbulence Models in Industrial Use.
10:00 Zheng-Tong Xie (University of Southampton): Challenges in coupling between meso-scale and micro-scale simulations.
10:20 Georgios Efstathiou (University of Exeter): Dynamic Turbulence Modelling in the ‘Terra-Incognita’ of turbulence.
10:40 Coffee Break
11:00 John Bruun (University of Exeter): Universal properties of turbulence cascades and opportunities to improve LES/RANS computations.
11:20 John Thuburn (University of Exeter): Diagnosing numerical dissipation in Implicit Large-Eddy Simulation.
11:40 Dimitar Vlaykov (University of Exeter): Dynamic Anisotropic Eddy-Diffusivity for multiscale simulations.
12:00 Panel discussion with session speakers
12:45 - 14:00 Lunch
Session 4: Real-World Applications of Grey-Zone Modelling | Chair: Paul Burns
14:00 Kirsty Hanley (Met Office): Hectometric modelling for the Paris 2024 Olympic and Paralympic summer.
14:20 Branko Kosovic (Johns Hopkins University): Multiscale simulations of flows in atmospheric boundary layers from mesoscale to microscale: challenges and opportunities.
14:40 Isabelle Gorst (University of Reading): An evaluation of horizontal convective roll characteristics and occurrence in sub-km simulations during the 2023 WesCon - WOEST campaign.
15:00 Coffee Break
15:30 Emanuele Silvio Gentile (Princeton University): Enhanced simulations of low-level jets and moisture transport over the US great plains by directly prognosing momentum flux and using a generalised turbulence length-scale.
15:50 Adrian Lock (Met Office): Experiences and challenges for operational NWP in the turbulent grey zone.
16:10 Paolo Gianni (Massachusetts Institute of Technology): Impact of Gray Zone Parameterizations on Realistic LES for Numerical Weather Prediction.
16:30 - 1715 Panel discussion with session speakers
19:00 Workshop BBQ-style dinner (Reed Hall, Streatham Campus, University of Exeter)
Day 3: Wednesday 25 June 2025
Session 5: Cumulus Convection in the Grey Zone | Chair: Bob Plant
09:00 Arrival Coffee
09:30 Roel Neggers (University of Cologne) (Featured talk): Exploring the turbulent/convective grey zone with a binomial thermal population model.
10:00 Samantha Smith (Met Office): An investigation into length scales for the Comorph convection scheme.
10:20 Dan Shipley (University of Reading): Examining EDMF-type approaches in the grey zone via conditional filtering.
10:40 Coffee Break
11:00 Gabriel Rooney (Met Office): Rain and shape effects on idealised downdraughts.
11:20 Panel Discussion with session speakers.
12:00 Concluding Remarks.
12:20 - 13:30 Lunch
End of Workshop