Revolutionizing Convective Parameterization

Lead Research Organisation: University of Reading
Department Name: Meteorology

Abstract

The weather and climate of the tropics is dominated by cumulus clouds. These clouds are produced by vigorous convection currents within the atmosphere. The convection communicates heat and evaporation from the Earth's surface throughout the atmosphere. It is the main process controlling the change of temperature and moisture content with height in the tropical atmosphere. On the global scale cumulus clouds are responsible for the majority of the rainfall, and convection is a crucial component in the overall pattern of the Earth's atmospheric flows.

Computer modelling of the atmosphere, both for global numerical weather prediction (NWP) and for climate projection, divides the atmosphere into boxes with typical horizontal sizes of 20 and 100km respectively. This means that the models are not able to represent convective elements (such as thunderstorms) properly, because these elements are typically only around 1km in size. However, as convection has a crucial role to play in the atmosphere, it must be represented within the models. We have somehow to estimate what cumulus clouds will be present in each of the boxes and what their collective effects will be on the larger-scale atmosphere. This is known as a cumulus parameterization.

Computer modelling of the atmosphere is essential for reliable climate projections and weather forecasts. Society benefits enormously from their outputs to inform decision making on all scales from the individual member of the public to weather-sensitive business activities to the insurance sector to the emergency services to government policy on climate risks. Convection parameterization is a stubborn and difficult problem and the largest single uncertainty that we face. It is a severe and unforgiving test of just how well we understand the fundamental science of convection and its role in the atmosphere. Defects in the existing parameterizations are known to translate into serious deficiencies in weather and climate models. To give just one example, in many models the predicted convective rainfall is too frequent and too light.

RevCon is so named because the project aims at a revolution in convective parameterization by challenging many of the key assumptions that have been made within convective parameterizations for decades. Some of these assumptions are very limiting and known to be poor approximations in many circumstances. We are also convinced that they are unnecessary and that better parameterizations can be achieved without them. This project will establish what the mathematical structure of convection parameterization really should be, with that structure being informed and carefully justified through the detailed analysis of very high-resolution simulations of convective cloud systems. It is a critical contribution to a NERC / Met Office programme in this area because it will provide a necessary starting point for Phase 2 of the programme to build a new-generation parameterization for the Met Office weather forecast and climate model.

Planned Impact

The primary impacts of this NERC / Met Office programme will be:

1. directly on the accuracy and utility of Met Office weather forecasts and climate predictions via implementation of improved convection parameterization in the Met Office's Unified Model (UM);

2. indirectly on other weather and climate prediction centres through promulgation of the methodology implemented;

3. indirectly on other weather and climate prediction centres through access to the reference data that the new methodology is based upon.

The RevCon project targets these impacts in a completely natural and straightforward way, since all of the project deliverables are important for the overall success of the programme and all map straightforwardly on to the above impacts. (Deliverables D1 and D2 in the Case for Support map to impact 3, D3 to D5 map to impacts 1 and 2, and D6 maps to impact 1).

A parameterization of convection is an essential ingredient in operational weather forecasting (including extreme events such as flooding), in seasonal weather forecasts and in regional and global climate models. A reliable and soundly-physically-based parameterization is therefore essential for the quality of weather forecasts and for reducing uncertainties in climate projections. Improved parameterization methods will ultimately impact end-users from government, industry and the public, through significant improvements to Met Office products and advice. The Met Office, in common with operational prediction centres worldwide, has made this issue a major priority. The Met Office has formal arrangements with a number of national meteorological services and research institutes around the world, concerning the use by these services of the UM. Therefore, these international partners, including Australia, Korea, new Zealand, Norway, India and South Africa, will also directly benefit from improvements to the UM.

The scientific understanding gained through this project will have similar impacts within other operational centres, and will drive forward the fundamental understanding of convection within the academic and broader WGNE (Working Group on Numerical Experimentation) community. This will be further facilitated by the availability of reference datasets from the RevCon project which will form the basis of further exploitation.

Ensuring the project's potentially very high impact requires two-way exchanges with scientists working on operational weather and climate prediction and a full engagement with the international community. We will achieve this by working with the Met Office (project partners) and through international communications and collaborations that will build new links and develop the existing links of the investigators with operational centres (eg, ECMWF, DWD, Meteo France).

Publications

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Daleu C (2020) Memory Properties in Cloud-Resolving Simulations of the Diurnal Cycle of Deep Convection in Journal of Advances in Modeling Earth Systems

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Hagos S (2018) A Stochastic Framework for Modeling the Population Dynamics of Convective Clouds in Journal of Advances in Modeling Earth Systems

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Honnert R (2020) The Atmospheric Boundary Layer and the "Gray Zone" of Turbulence: A Critical Review in Journal of Geophysical Research: Atmospheres

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McIntyre W (2020) Numerical methods for entrainment and detrainment in the multi-fluid Euler equations for convection in Quarterly Journal of the Royal Meteorological Society

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Weller H (2019) Numerical solution of the conditionally averaged equations for representing net mass flux due to convection in Quarterly Journal of the Royal Meteorological Society

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Weller H (2020) Multifluids for Representing Subgrid-Scale Convection in Journal of Advances in Modeling Earth Systems

Studentship Projects

Project Reference Relationship Related To Start End Student Name
NE/N013743/1 01/08/2016 31/05/2020
1787146 Studentship NE/N013743/1 01/10/2016 30/09/2019 William McIntyre
 
Description Understanding and Representing Atmospheric Convection across Scales - ParaCon Phase 2
Amount £962,484 (GBP)
Funding ID NE/T003871/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2019 
End 03/2022
 
Description Poster at: EGU General Assembly, 8-13 April 2018, Vienna, Austria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Jonathan Chui on A stochastic and prognostic convective parameterisation scheme for the "grey-zone". Jonathan is a PhD student closely aligned to this project, and we have plans to further develop his work and exploit his results within the ParaCon programme.
Year(s) Of Engagement Activity 2018
 
Description Posters at: The Future of Cumulus Parametrization, 10-14 July 2017, TU Delft, Netherlands. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster presentation on Dynamic sub-grid modelling of shallow cumulus convection drew on work for the GREYBLs and RevCon projects. Additionally a poster presentation on Satellite observations of Bermuda's island-induced clouds drew on work for the RevCon project.
Year(s) Of Engagement Activity 2017
 
Description Talk at: Nanjing University Seminar, 25 October, Nanjing, China 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact A poster was presented by Jian-Feng Gu describing work on Key components of Convection for Vertical Transport of Heat and Moisture: A Core-cloak Conceptual Model. The presentation was made at his fomer university and students were included in the audience.
Year(s) Of Engagement Activity 2019
 
Description 5th OpenIFS Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The Department of Meteorology at Reading hosted the 5th OpenIFS user workshop, co-organized by myself and a colleague at Reading, and there members of staff from ECMWF. This was a week-long event. The participants gained hands-on experience of the ECWMF forecast model in particular, but also learned about numerical weather prediction in general. A particular focus was in how case study simulations are affected by different parameterized processes in the model.

The link below points to a newsletter article summarising the workshop.
Year(s) Of Engagement Activity 2019
URL https://www.ecmwf.int/en/elibrary/19156-newsletter-no-160-summer-2019
 
Description Organizing committee for Convection Parametrization: Progress and Challenges 2019, 15-19 July, Met Office, Exeter. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The workshop was organized by the Met Office and by the ParaCon programme and included both academics and operational scientists. It was important not least for guiding the ParaCon programme in its transition from Phase 1 to Phase 2. CoI Holloway served on the organizing committee.
Year(s) Of Engagement Activity 2019
URL https://sites.exeter.ac.uk/convection-workshop/
 
Description Participation at ECMWF Workshop on Sheddling Light on the Grey Zone 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Participation included a presentation based on this project work and participation in a working group providing recommendations for future research directions at ECMWF
Year(s) Of Engagement Activity 2017
URL https://www.ecmwf.int/en/learning/workshops/shedding-light-greyzone
 
Description Poster at: 2018 ARM/ASR PI Meeting, 19-23 March, Vienna, Virginia, USA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Samson Hagos of PNNL describing joint work on A Stochastic Framework for Modeling the Population Dynamics of Convective Clouds. The meeting included both academics and operational scientists.
Year(s) Of Engagement Activity 2018
 
Description Poster at: 2019 Joint ARM User Facility and ASR PI Meeting, 10-13 June, Rockville, Maryland, USA. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Samson Hagos of PNNL describing joint work on A Machine Learning Assisted Development of a Model for the Population Dynamics of Clouds. The meeting included both academics and operational scientists.
Year(s) Of Engagement Activity 2019
 
Description Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Steve Sherwood, describing joint work between the RevCon team, the Met Office, the university of New South Wales and the Sorbonne. The title was Characterising Convective Schemes by Their Linearised Responses.

We intend to build on this analysis to assess the behaviour of Comorph within Phase 2.
Year(s) Of Engagement Activity 2019
 
Description Poster at: EGU General Assembly, 8-13 April 2018, Vienna, Austria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Mark Muetzelfeldt presented a poster on Effects of wind shear on cloud field organization to a mixture of academics and operational scientists. Mark is a PhD student closely aligned with the ParaCon programme and we intend to build on some of his results within our RevCon work.
Year(s) Of Engagement Activity 2018
 
Description Poster at: EMS Annual Meeting, 3-7 September, Corvinus University of Budapest, Hungary. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Michael Johnston at the European Meteorological Society meeting which attracts both academics and operational researchers. Michael is a PhD student closely aligned to ParaCon and we intend to draw on some of his work on Environments that support organised shallow island convection in devising idealized simulations within this project.
Year(s) Of Engagement Activity 2018
 
Description Poster at: Met Office Academic Partnership Meeting, 15-16 February 2018, Exeter. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Mark Muetzelfeldt presented a poster on Clustering wind profiles to identify shear conditions in climate models at the Met Office. Mark is a PhD student whose work is closely aligned with ParaCon and we intend to build on some of his results in the later stages of this project.
Year(s) Of Engagement Activity 2018
 
Description Poster at: RMetS Students & Early Career Scientist Conference, Evolution of Science: Past, Present and Future, 5-6 July, University of York. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Nadie Rupasinghe on Do the properties of convective clouds converge at high resolution? This was work for her MSc dissertation, and which was supervised by the RevCon PI as part of his contribution towards this project, alongside Todd Jones as part of his PDRA work on the sister-project Circle-A within the ParaCon programme.
Year(s) Of Engagement Activity 2018
 
Description Seminar by H Weller at the University of Hamburg, 18 December 2019 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact H Weller presented a seminar on Multi-fluid modelling for atmospheric convection
Year(s) Of Engagement Activity 2019
 
Description Talk and poster at: EGU General Assembly, 7-12 April 2019, Vienna, Austria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A poster was presented by Samson Hagos of PNNL describing joint work on A Machine Learning Assisted Development of a Model for the Population Dynamics of Clouds. The meeting included both academics and operational scientists. The meeting also provided an excellent opportunity for Dr Hagos and the project PI Plant to collaborate on this work.

Also a poster was presented by Michael Johnston describing his work on Large-eddy resolution simulation of organised convection on a small island. Michael is a PhD student closely aligned to ParaCon and we intend to draw on some of this work in devising idealized simulations within this project.

Also an invited talk was presented by Robert Plant, and this is described under the Awards and Recognition category.
Year(s) Of Engagement Activity 2019
 
Description Talk at ECMWF Physics-Dynamics coupling workshop, 10-12 July, ECMWF 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was given by Hilary Weller (co-I) on her work with the project-funded PhD student Will McIntyre, on Coupling Convection with the Continuity Equation - a Multi-fluid approach. The workshop comprised academics and operational scientists,.
Year(s) Of Engagement Activity 2018
URL https://www.ecmwf.int/en/learning/workshops/3rd-workshop-physics-dynamics-coupling-pdc18
 
Description Talk at: 2019 AMS Annual Meeting, 6-10 January, Phoenix, Arizona, USA. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was presented by Samson Hagos of PNNL on our joint work on A Stochastic Transition Matrix Approach to Modeling of the Population Dynamics of Clouds. The conference attendees included both academic and operational scientists.
Year(s) Of Engagement Activity 2019
 
Description Talk at: 2nd Global Atmospheric System Studies (GASS) Conference, 26 February - 2 March, Lorne, Victoria, Australia. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was given by Samson Hagos of PNNL on our joint work on A Stochastic Framework for Modeling the Population Dynamics of Convective Clouds. The conference included both academic and operational scientists.
Year(s) Of Engagement Activity 2018
 
Description Talk at: AGU Fall Meeting, 10-14 December, Washington, USA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact A talk was given by Todd Jones. Todd is a PDRA on the Circle-A project which is a part of the ParaCon programme alongside this RevCon project. He presented a talk that covered work done jointly within RevCon and Circle-A, specifically on Radiative Convective Equilibrium Across the Gray Zone
Year(s) Of Engagement Activity 2018
 
Description Talk at: Convection Parametrization: Progress and Challenges 2019, 15-19 July, Met Office, Exeter. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The workshop was organized by the Met Office and by the ParaCon programme and included both academics and operational scientists. It was important not least for guiding the ParaCon programme in its transition from Phase 1 to Phase 2.

Contributions from the RevCon team to the workshop included:

A talk was presented by Chimene Daleu describing work on The simulation of the diurnal cycle of deep convection over land in a new Met Office Cloud-Resolving model.
A talk was presented by Jian-Feng Gu describing work on Evaluation of bulk mass flux formulation using large-eddy simulations
A poster was presented by Jian-Feng Gu describing work on A composite study of cloud structure and its implication for the parameterization of vertical fluxes
A poster was presented by Natalie Harvey describing joint work between herself and several members of the RevCon team on Understanding the impact of surface heterogeneity on the diurnal cycle of deep convection
A talk was presented by Micahel Johnston describing work on Cloud Trails: Are the clouds important? (Michael is a PhD student closely aligned to ParaCon and we intend to draw on some of his work on Environments that support organised shallow island convection in devising idealized simulations within this project.)
A talk was presented by Mark Muetzelfeldt describing work on Using a cloud-resolving model to diagnose the effects of different wind shear profiles on deep convective cloud fields (Mark is a PhD student whose work is closely aligned with ParaCon and we intend to build on some of his results in the later stages of this project.)
A talk was presented by Chris Holloway describing work on Using convective aggregation to inform convection parametrization development
Year(s) Of Engagement Activity 2019
URL https://sites.exeter.ac.uk/convection-workshop/
 
Description Talk at: UCP2019 Understanding Clouds and Precipitation, Berlin, 25 February - 1 March 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was given by Alison Stirling of the Met Office on ParaCon's parametrisation of convection at kilometre scales. This described progress on the ParaCon programe generally, including the work under RevCon. The meeting included both academics and operational scientists.
Year(s) Of Engagement Activity 2019
 
Description Talk at: UM User Workshop 2019, 17-21 June, Met Office, Exeter 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was presented by Chimene Daleu describing Idealized modelling of the diurnal cycle of deep convection using the new Met Office Cloud-Resolving Model (MONC). The meeting was focussed on operational scientists from the Met Office and its international partners.
Year(s) Of Engagement Activity 2019
 
Description Three project posters at: UCP2019 Understanding Clouds and Precipitation, Berlin, 25 February - 1 March 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Three posters relating to this project were presented at the UCP meeting, which attracted both academics and operational scientists. One was presented by Jian-Feng Gu (a PDRA on the project) on A core-cloak representation of convection, a second by Chris Holloway (a co-I on the project) covering work by this project and the Circle-A sister-project on ParaCon at Reading: New approaches for modelling convection, and a third by Mark Muetzelfeldt (a closely-affiliated PhD student, presenting work which we have hopes to follow-up within RevCon) on Using a cloud-resolving model to diagnose the effects of different wind shear profiles on deep convective cloud fields.
Year(s) Of Engagement Activity 2019