Virtual training course: Parametrization of subgrid physical processes

Europe/London
ECMWF

ECMWF

Description

COVID-19 (coronavirus) update

17 March 2020

As the situation around COVID-19 (coronavirus) continues to evolve we understand you will have questions about its impact on ECMWF events. At this stage, no events have been cancelled and we hope all scheduled events will take place as planned.

We are monitoring the situation closely and will notify registered participants if we need to postpone an event or deliver it virtually rather than physically. Due to this uncertain situation, ECMWF recommends that participants ensure that any travel and accommodation arrangements are made with appropriate cancellation policies until further notice.

Thank you for your understanding; for the most up-to-date information, continue checking this webpage.

This five-day module is a combination of lectures, hands-on practicals using the Single Column Model, and group problem classes.

During the course each parametrized process is introduced and then discusses theory, modelling and verification over several sessions.

Processes considered

  • General aspects of parametrization and their relation to systematic forecast errors
  • Radiation in numerical weather prediction
  • The parametrization of moist processes (convection and clouds)
  • The planetary boundary layer
  • Land surface processes
  • Parametrization of subgrid-scale orographic effects
  • The representation of physical processes in data assimilation

Pre-course study

Participants will be expected to take up to 4 online modules before taking the course.  This will provide introductory information on parametrization, convection, single column modelling and the metview interface that will be used in the practical sessions.

It is anticipated that this study will take around 4 hours depending on levels of prior knowledge.

Requirements

Participants should have a good meteorological and mathematical background, and are expected to be familiar with the contents of standard meteorological and mathematical textbooks.

Introductory material not covered by the course can be found in our lecture note series.

Some practical experience in numerical weather prediction is an advantage.

All lectures will be given in English.

Events team
    • 09:15 09:20
      Welcome, course overview 5m
      Speaker: Sarah Keeley (ECMWF)
    • 09:20 10:15
      Introductions (course participants and lecturers)
      Conveners: Andy Brown (ECMWF), Dr Sarah Keeley (ECMWF)
    • 10:15 10:30
      Break 15m
    • 10:30 11:30
      Convection (1) 1h

      Convection affects all atmospheric scales. Therefore, the convection session aims to provide a deeper understanding of the atmospheric general circulation and its interaction with convective heating and vertical transports. The notions and techniques acquired during the course should be useful for developers of convective parametrizations, forecasters and for analysing output from high-resolution convection resolving models.

      By the end of the session you should become familiarised with

      • the interaction between the large-scale circulation and the convection including radiative-convective equilibrium and convectively-coupled large-scale waves
      • the notion of convective adjustment and the mass flux concept in particular
      • the basic concepts behind the ECMWF convection parametrization and some useful numerical tricks
      • forecasting convection including convective systems and the diurnal cycle
      • diagnose forecast errors related to convection.

      Speaker: Peter Bechtold (ECMWF)
    • 11:30 11:35
      Comfort break 5m
    • 11:35 12:35
      Radiation (1) 1h

      This module aims to introduce the fundamentals of radiative transfer theory and its role within the global atmospheric circulation. The lectures will also cover the techniques of numerical modelling of the radiative transfer equations in global-circulation models with a particular focus on the code in use in the ECMWF Integrated Forecasting System.
      By the end of the session students should be able to:
      • Identify the key processes controlling the atmospheric radiative balance
      • Recognize the role of the radiative transfer in the Earth energy balance
      • Estimate the impact of changes in the radiative parameterizations on climate

      Additional outcomes:

      • Develop skills in data analysis and numerical modelling

      Speaker: Robin Hogan (ECMWF)
    • 12:35 13:30
      Lunch break 55m
    • 13:30 14:30
      Clouds (1) 1h

      This session gives a brief overview of cloud parametrization issues and an understanding of the basic microphysics of liquid, ice and mixed phase cloud and precipitation processes.
      By the end of the session you should be able to:
      • recall the basic concepts for the design of a cloud parametrization
      • describe the key microphysical processes in the atmosphere
      • recognize the important microphysical processes that need to be parametrized in a global NWP model.

      Speaker: Richard Forbes (ECMWF)
    • 14:30 14:45
      Break 15m
    • 14:45 15:45
      Boundary layer (1) 1h

      This session gives a theoretical introduction of the planetary boundary layer, including its definition, classification, notions about turbulence within the boundary layer, differences between clear and cloudy boundary layers, and equations used to describe the mean state in a numerical model.
      Expected outcomes:
      • understand what is the boundary layer, its characteristics and why it is important to study it and represent it correctly in numerical models
      • understand the difference between the various boundary layer types

      Speaker: Irina Sandu (ECMWF)
    • 09:15 10:15
      Radiation (2) 1h

      This module aims to introduce the fundamentals of radiative transfer theory and its role within the global atmospheric circulation. The lectures will also cover the techniques of numerical modelling of the radiative transfer equations in global-circulation models with a particular focus on the code in use in the ECMWF Integrated Forecasting System.
      By the end of the session students should be able to:
      • Identify the key processes controlling the atmospheric radiative balance
      • Recognize the role of the radiative transfer in the Earth energy balance
      • Estimate the impact of changes in the radiative parameterizations on climate
      Additional outcomes:
      • Develop skills in data analysis and numerical modelling

      Speaker: Robin Hogan (ECMWF)
    • 10:15 10:30
      Break 15m
    • 10:30 11:30
      Clouds (2) 1h

      This session describes the representation of subgrid-scale variability of humidity, cloud and precipitation and how this can be parametrized in atmospheric models.
      By the end of the session you should be able to:
      • recognise the reasons for representing the subgrid variability of humidity and cloud in an atmospheric model
      • explain how the key quantity of cloud fraction is related to subgrid heterogeneity assumptions
      • describe the different types of subgrid cloud parametrization schemes.

      Speaker: Richard Forbes (ECMWF)
    • 11:30 11:35
      Comfort break 5m
    • 11:35 12:35
      Radiation (3) 1h

      This module aims to introduce the fundamentals of radiative transfer theory and its role within the global atmospheric circulation. The lectures will also cover the techniques of numerical modelling of the radiative transfer equations in global-circulation models with a particular focus on the code in use in the ECMWF Integrated Forecasting System.
      By the end of the session students should be able to:
      • Identify the key processes controlling the atmospheric radiative balance
      • Recognize the role of the radiative transfer in the Earth energy balance
      • Estimate the impact of changes in the radiative parameterizations on climate
      Additional outcomes:
      • Develop skills in data analysis and numerical modelling

      Speaker: Mark Fielding (ECMWF)
    • 12:35 13:30
      Lunch break 55m
    • 13:30 14:30
      Boundary layer (2) 1h

      This session focuses on representation of the surface layer, i.e. the layer between the surface and the first model level. More particularly, it explains how the surface fluxes are parametrized, and it gives insights on the representation of the surfaces roughness lengths which are one of the crucial aspects of the formulation of the surface fluxes.
      Expected outcomes:
      • be aware of the difficulties related to the representation of the surface layer in a numerical model
      • understand how the surface fluxes are parametrized

      Speaker: Irina Sandu (ECMWF)
    • 09:15 10:15
      Land surface - introduction 1h

      By the end of the session students should be able to:
      • recognise land elements relevant to weather,
      • review land modelling strategies to heterogeneity

      Speaker: Gianpaolo Balsamo (ECMWF)
    • 10:15 10:30
      Break 15m
    • 10:30 11:30
      Convection (2) 1h

      Convection affects all atmospheric scales. Therefore, the convection session aims to provide a deeper understanding of the atmospheric general circulation and its interaction with convective heating and vertical transports. The notions and techniques acquired during the course should be useful for developers of convective parametrizations, forecasters and for analysing output from high-resolution convection resolving models.
      By the end of the session you should become familiarised with
      • the interaction between the large-scale circulation and the convection including radiative-convective equilibrium and convectively-coupled large-scale waves
      • the notion of convective adjustment and the mass flux concept in particular
      • the basic concepts behind the ECMWF convection parametrization and some useful numerical tricks
      • forecasting convection including convective systems and the diurnal cycle
      • diagnose forecast errors related to convection.

      Speaker: Peter Bechtold (ECMWF)
    • 11:30 11:35
      Comfort break 5m
    • 11:35 12:35
      Land surface - warm processes 1h

      This session will have two main components:
      • An overview of the role of snow in the climate system from observations, models and forecasts; with a description of the current representation of snow in the ECMWF model.
      • An overview of the role of vegetation in NWP with a description of the evolution of vegetation representation in the ECMWF model, supported by some evaluation examples.
      By the end of the session, the students should be able:
      • Identify the main processes associated with snow and vegetation in NWP
      • Describe the main components related to snow and vegetation scheme in the ECMWF land surface model

      Speaker: Souhail Boussetta (ECMWF)
    • 12:35 13:30
      Lunch break 55m
    • 13:30 14:30
      Land surface - cold processes 1h
      Speaker: Gabriele Arduini (ECMWF)
    • 09:15 10:15
      Clouds (3) 1h

      Building on the previous two Cloud sessions, the practical implementation of a cloud parametrization is described, using the ECMWF global model as an example appropriate for global weather forecasting.
      By the end of the session you should be able to:
      • explain the key sources and sinks of cloud and precipitation required in a parametrization
      • describe the main components of the ECMWF stratiform cloud parametrization
      • recognise the limitations of approximating complex processes.

      Speaker: Richard Forbes (ECMWF)
    • 10:15 10:30
      Break 15m
    • 10:30 11:30
      Convection (3) 1h

      Convection affects all atmospheric scales. Therefore, the convection session aims to provide a deeper understanding of the atmospheric general circulation and its interaction with convective heating and vertical transports. The notions and techniques acquired during the course should be useful for developers of convective parametrizations, forecasters and for analysing ouput from high-resolution convection resolving models.
      By the end of the session you should become familiarised with
      • the interaction between the large-scale circulation and the convection including radiative-convective equilibrium and convectively-coupled large-scale waves
      • the notion of convective adjustment and the mass flux concept in particular
      • the basic concepts behind the ECMWF convection parametrization and some useful numerical tricks
      • forecasting convection including convective systems and the diurnal cycle
      • diagnose forecast errors related to convection.

      Speaker: Peter Bechtold (ECMWF)
    • 11:30 11:35
      Comfort break 5m
    • 11:35 12:35
      Boundary layer (3) 1h

      This session explains the different approaches used in numerical models to parametrize the turbulent mixing taking place at the subgrid scale, above the surface layer. Various turbulence closures are presented before describing closure currently used in the ECMWF model.
      Expected outcomes:
      • understand what a turbulence closure is and what are the types of closures encountered in numerical models
      • have an overview of the parameterization of turbulent mixing in the ECMWF model

      Speaker: Irina Sandu (ECMWF)
    • 12:35 13:30
      Lunch break 55m
    • 13:30 14:30
      Model evaluation: Clouds and boundary layer 1h

      This session will give an overview of techniques and data sources used for the verification of the boundary layer scheme. We will use examples from the IFS to explore how verification methods can help to identify systematic errors in the model's boundary layer parameterization, and guide future model development.
      By the end of this session you should be able to:
      • Identify data sources and products suitable for BL verification
      • Recognize the strengths and limitations of the verification strategies discussed
      • Choose a suitable verification method to investigate model errors in boundary layer height, transport and cloudiness.

      Speaker: Richard Forbes (ECMWF)
    • 09:15 10:15
      Parametrization and data assimilation 1h

      This two-hour lecture will start by explaining the role and main ingredients of data assimilation in general. The widely used framework of variational data assimilation will then be gradually introduced. The challenges associated with the necessary inclusion of physical parametrizations in the data assimilation process will be highlighted. The concept of adjoint model as well as the techniques to derive it will be introduced. The importance of the linearity constraint in 4D-Var and the methods to address it will be detailed. The set of linearized physical parametrizations used at ECMWF will then be briefly presented. Finally, various examples of the use of physical parametrizations in variational data assimilation and its impact on weather forecast quality will be given.
      By the end of the session, the students should be able:
      • to name the main ingredients of a data assimilation system.
      • to tell why physical parametrizations are needed in data assimilation.
      • to identify the role of the adjoint code in 4D-Var.
      • to recognize the importance of the regularization of the linearized code.

      Speaker: Philippe Lopez (ECMWF)
    • 10:15 10:30
      Break 15m
    • 10:30 11:30
      Parametrization and data assimilation 1h
      Speaker: Philippe Lopez (ECMWF)
    • 11:30 11:35
      Comfort break 5m
    • 11:35 12:35
      Parametrization of sub-grid orography 1h

      On the basis of simple gravity wave theory, the concepts of sub-grid turbulent form drag, flow blocking, and gravity wave excitation will be introduced. The ECMWF formulations will be described, and the impact will be discussed.
      By the end of the session students should be able to:
      • Describe the relevant physical mechanisms related to sub-grid orography that have impact on flow in the atmosphere.
      • Describe the impact of sub-grid orography.

      Speaker: Irina Sandu (ECMWF)