Workshop: Shedding light on the greyzone

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ECMWF | Reading | 13 - 16 November 2017

The workshop brought together experts in numerical weather prediction and climate modelling to discuss and propose ways forward on the modelling of physical processes in the greyzone of horizontal resolutions ranging from 1 km-10 km grid-spacing. The workshop aimed to shed light on the greyzone topic from different angles to identify novel approaches and development opportunities.

Topics discussed included the required complexity of cloud microphysics, the interaction of cloud microphysics, convection and boundary layer turbulence, the interaction with and the representation of the surface heterogeneity, including orography and vegetation over land and the sea-surface state over the ocean, and the physics-dynamics interplay with increasing resolution, including difficulties and opportunities arising from emerging HPC architectures.

These were discussed in the context of the inherent uncertainty of the above modelled processes (or of the underlying HPC hardware) and in view of ECMWF's ten year strategy to develop a 5km global ensemble.

Presentations and recordings

Monday 13 November

  Presentation Recording
Andy Brown/Nils Wedi (ECMWF)
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European cloud moist work so far
Peter Bechtold (ECMWF)
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NWP model tuning for the convective greyzone: operational experience at DWD and possible pathways towards the convection-resolving scale
Günther Zängl (DWD)

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Greyzone in the Great White North: Recent developments at the Canadian Meteorological Centre
Ron McTaggart-Cowan (CMC) 
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Experiences with Convection Permitting versions of the UM
Humphrey Lean (MetOffice)  
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PBL and precipitation interaction and greyzone issues
Song You Hong (KIAPS)
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Tuesday 14 November

  Presentation Recording
Some light shed on the grey zone of turbulence
Rachel Honnert (Météo-France)
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Dynamic sub-grid modelling of an evolving CBL at grey-zone resolutions
George Efstathiou (University of Exeter)

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From small-scale turbulence to large-scale convection: a unified scale-adaptive EDMF parameterization
Kay Sušelj (JPL)
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On the use of a TKE equation to compute subgrid fluxes in the "Grey Zone"
Stephan de Roode (TU Delft)

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Entropy production as a constraint to subgrid-scale modeling: role of subgrid scales for the simulation of breaking gravity waves
Almut Gassmann (IAP)
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A new stochastic, scale-aware convection scheme for the Met Office Unified Model
Michael Whitall (Met Office)

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Going through the grey zone of deep convection with the ALADIN System
Piet Termonia (RMI/Aladin)

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A scale-aware convective parameterization scheme developed by KIAPS
Young Kwon (KIAPS)

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Convection in weather forecasts at 40km to 100m resolution over summer land and the tropical Atlantic
Daniel Klocke/Martin Köhler (DWD)
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CRM and LES approaches for simulating tropical deep convection: successes and challenges
Jean-Pierre Chaboureau (Laboratoire d'Aerologie)
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Necessity of parametrizations for convective initiations and controlling convections in high resolution cloud permitting models
Tabito Hara (JMA)
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Numerical realization of thermal convection at kilometer scale
Zbigniew Piotrowski (IMGW)
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Challenges in parameterization of shallow convection on kilometre scales
Mirjana Sakradzija (MPI)
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Wednesday 15 November

  Presentation Recording
Exploring stochastic model uncertainty representations
Sarah-Jane Lock (ECMWF)
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Representation of model uncertainty in a convectiOn permitting EPS - HarmonEPS
Inger-Lise Frogner (Met Norway / HIRLAM)

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The Irish Regional Ensemble (IRE): development of a convection-permitting EPS at Met Éireann
Alan Hally (Met Éireann)
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Scale issues for atmospheric modelling at urban scale
Valéry Masson (Météo-France)
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Orographic drag and the mountain-wave grey zone
Annelize van Niekerk (Met Office)
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Land surface-atmosphere interaction approaching high resolution
Patrick Samuelsson (SMHI)
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Developing a km-scale model system over the Alpine arc
Oliver Fuhrer (Meteo Swiss)
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Simulation in the greyzone with the Finite-Volume Module of the IFS
Christian Kühnlein (ECMWF)
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Coupling physical parameterizations to a three-dimensional spectral element model
Alex Reinecke (NRL)
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Physics-dynamics coupling for GungHo
Ben Shipway (Met Office / Gung-Ho)
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Working group reports

Working group 1  
Working group 2  
Working group 3 PDF icon

Organising committee

Peter Bechtold, Michail Diamantakis, Richard Forbes, Martin Leutbecher, Sarah-Jane Lock, Sylvie Malardel, Irina Sandu, Nils Wedi