Understanding and Representing Atmospheric Convection across Scales - ParaCon Phase 2

Lead Research Organisation: University of Reading
Department Name: Meteorology

Abstract

Cumulus clouds are produced by the vigorous ascent of buoyant air, a process known as convection. The weather and climate of the tropics are dominated by cumulus clouds, and severe weather at all latitudes involves convection. Convection communicates heat and moisture 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 is essential for both numerical weather prediction (NWP) and climate projections. 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, the energy sector, the emergency services, and government policy on climate risks. Computer models for NWP and for climate projection divide the atmosphere into boxes with typical horizontal sizes of 10km and 100km respectively. Convective elements such as thunderstorms, on the other hand, are typically only around 1km in size so they cannot be explicitly represented in the models. Instead we must somehow 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.

Cumulus parameterization is a stubborn and difficult problem and is 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. These include errors in the distribution, timing, and intensity of convective rainfall, as well as the behaviour of larger-scale weather systems that are coupled to convection.

ParaCon Phase 2 is a wide-ranging plan to redesign the convection parameterization for the Met Office Model, to demonstrate clear improvements in model fidelity and performance, and to lay the groundwork for the next generation of parameterization research.

In Phase 1 we have developed a new convection scheme infrastructure called CoMorph, which enables many of the assumptions that are made in such parameterizations to be relaxed, removed or generalized and we have begun the process of developing a formulation based on alternative and more general assumptions. Also in Phase 1 we have performed promising investigations into radically different formulations based on modelling convection as a manifestation of turbulence, and on a multi-fluid approach that relaxes the usual assumptions even further than CoMorph does.

In Phase 2 we will continue the development of CoMorph with a view to its adoption for operational forecasting. Building on the work in Phase 1, improved formulations for the components of the scheme will be developed and implemented. The performance of CoMorph will be evaluated in a wide range of test cases. These will include comparison with a suite of high-resolution simulations of idealized convective archetypes conducted in Phase 1, as well as a range of operational-style configurations.

In Phase 2 we will also continue to develop the turbulence-based and multi-fluid-based approaches and to evaluate their potential for representing convection in atmospheric models. A key goal will be to clarify the relationship between the three approaches and to understand the extent to which some unification or combination of the approaches might be possible and beneficial.

Planned Impact

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 primary impacts of ParaCon Phase 2 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 specific methodology implemented, and of alternative strategies for future parameterization developments and evaluation techniques;

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

ParaCon targets the first of these impacts in a completely natural and straightforward way, since the programme has been designed as a joint venture between the Met Office and the university partners with this impact at the very heart of the design. The partners and the Met Office have a long history of collaboration in model development projects, which has only been enhanced through our joint work in Phase 1. Thus, strong relationships between staff already exist that we will draw upon extensively in ensuring that our parameterization developments will be translated into operational practice.

The scientific understanding gained through this project will lead to substantial benefits for the second and third impacts within other operational centres, and will drive forward the fundamental understanding of convection within the academic, operational and broader WGNE (Working Group on Numerical Experimentation) communities. This will be further facilitated by the availability of reference datasets from the ParaCon project which will form the basis of further exploitation. A good example from Phase 1 is our involvement in both the design and delivery of the international RCEmip project, which was led by Jones (a PDRA from the Circle-A project) and Holloway (a co-I from the RevCon project).

Ensuring the project's very high impact will require close interactions with scientists working on operational weather and climate prediction and a full engagement with the international community. We will achieve this by continuing to build on new links and further developing and exploiting the existing links of the senior investigators with operational centres (eg, ECMWF, DWD, Meteo France, RNMI, SAWS).

With respect to other centres, we also note that the Met Office has formal arrangements with a substantial 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. Members of the ParaCon university teams are already engaged in some of the knowledge transfer and working group activities between the Met Office and its partners: for example, Plant, Clark and Birch have participated in meetings of the Convection Working Group.

Publications

10 25 50
 
Description Multi-fluid analogues of the turbulent second-order moment equations have been derived and documented; they should provide the basis for a better treatment of turbulence in
developing the multi-fluid approach to representing convection in atmospheric models.
Exploitation Route This development is an important early outcome of the work, and will be further developed during the remainder of the grant.
Sectors Education,Environment

 
Description Mesoscale Convective Systems: PRobabilistic forecasting and upscale IMpacts in the grey zonE (MCS:PRIME)
Amount £618,745 (GBP)
Funding ID NE/W005530/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 03/2022 
End 03/2025
 
Title Data supporting 'Pressure drag for shallow cumulus clouds: from thermals to cloud ensemble' 
Description This dataset is used to understand the pressure drag of shallow cumulus clouds, the relationship between the pressure drag of individual clouds and the cloud ensemble. We performed large eddy simulations of shallow cumulus clouds based on the Barbados Oceanographic and Meteorological Experiment (BOMEX) using the Met Office-NERC (National Environment Research Council) Cloud model (MONC). The grid spacing is 25 m in all directions and the domain size is (15X15X3) km^3. As the whole simulation has a huge dataset, we present a subset of the results that can be used to reproduce the figures in 'Pressure drag for shallow cumulus clouds: from thermals to cloud ensemble' (submitted to Geophysical Research Letters; 2020). Access to the all simulation data can be provided on request. The full dataset will be deposited in the CEDA Archive in due course. The dataset contains four sub-directories with generated data and another sub-directory with scripts for plotting the figures in the article. The generated data include: [1]. The conditionally averaged budget terms in vertical velocity equation for different parts of cloud ensemble; [2]. The conditionally averaged budget terms in vertical velocity equation for all tracked clouds; [3]. The conditionally averaged budget terms in vertical velocity equation for tracked clouds with different lifetime; [4]. The conditionally averaged budget terms in vertical velocity equation for each individually tracked cloud over its lifetime; [5]. The vertical cross section data of cloud structure; [6]. The positions of tracked clouds; [7]. The composited structure of clouds at 600m, 1000m and 1800m. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://researchdata.reading.ac.uk/id/eprint/259
 
Description Collaboration with Met Office 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Academic/University 
PI Contribution We have worked closely with the the Met Office a) developing and testing a new turbulence scheme in the Unified Model and b) Adding functionality to the new Met Office/NERC cloud model (MONC).
Collaborator Contribution One Met Office member of staff has worked very closely with me developing the new turbulence scheme in the Unified Model for approx one year.
Impact New diagnostic functionality in MONC model.
Start Year 2017
 
Description Multi-institute collaboration to test convection parameterizations 
Organisation Ewha Womans University, Seoul
Country Korea, Republic of 
Sector Academic/University 
PI Contribution The collaboration is a multi-institute group led from the University of New South Wales to assess the linear response characteristics of a wide range of convection paramterizations subjected to perturbed forcings.
Collaborator Contribution As noted above
Impact Single discipline - Meteorology. Outputs: Y. L. Hwong, S. Song, S. C. Sherwood, A. J. Stirling, C. Rio, R. Roehrig, C. L. Daleu, R. S. Plant, D. Fuchs, P. Maher, and L. Touzé-Peiffer. Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations. Submitted to: J. Adv. Model. Earth Syst., 2021. S. Song, Y.-L. Hwong, S. C Sherwood, A. Stirling, C. Rio, R. Roehrig, C. L. Daleu, and R. S. Plant. Characterising Convective Schemes by Their Linearised Responses, 2019. Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA
Start Year 2019
 
Description Multi-institute collaboration to test convection parameterizations 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Academic/University 
PI Contribution The collaboration is a multi-institute group led from the University of New South Wales to assess the linear response characteristics of a wide range of convection paramterizations subjected to perturbed forcings.
Collaborator Contribution As noted above
Impact Single discipline - Meteorology. Outputs: Y. L. Hwong, S. Song, S. C. Sherwood, A. J. Stirling, C. Rio, R. Roehrig, C. L. Daleu, R. S. Plant, D. Fuchs, P. Maher, and L. Touzé-Peiffer. Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations. Submitted to: J. Adv. Model. Earth Syst., 2021. S. Song, Y.-L. Hwong, S. C Sherwood, A. Stirling, C. Rio, R. Roehrig, C. L. Daleu, and R. S. Plant. Characterising Convective Schemes by Their Linearised Responses, 2019. Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA
Start Year 2019
 
Description Multi-institute collaboration to test convection parameterizations 
Organisation Sorbonne University
Country France 
Sector Academic/University 
PI Contribution The collaboration is a multi-institute group led from the University of New South Wales to assess the linear response characteristics of a wide range of convection paramterizations subjected to perturbed forcings.
Collaborator Contribution As noted above
Impact Single discipline - Meteorology. Outputs: Y. L. Hwong, S. Song, S. C. Sherwood, A. J. Stirling, C. Rio, R. Roehrig, C. L. Daleu, R. S. Plant, D. Fuchs, P. Maher, and L. Touzé-Peiffer. Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations. Submitted to: J. Adv. Model. Earth Syst., 2021. S. Song, Y.-L. Hwong, S. C Sherwood, A. Stirling, C. Rio, R. Roehrig, C. L. Daleu, and R. S. Plant. Characterising Convective Schemes by Their Linearised Responses, 2019. Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA
Start Year 2019
 
Description Multi-institute collaboration to test convection parameterizations 
Organisation University of New South Wales
Country Australia 
Sector Academic/University 
PI Contribution The collaboration is a multi-institute group led from the University of New South Wales to assess the linear response characteristics of a wide range of convection paramterizations subjected to perturbed forcings.
Collaborator Contribution As noted above
Impact Single discipline - Meteorology. Outputs: Y. L. Hwong, S. Song, S. C. Sherwood, A. J. Stirling, C. Rio, R. Roehrig, C. L. Daleu, R. S. Plant, D. Fuchs, P. Maher, and L. Touzé-Peiffer. Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations. Submitted to: J. Adv. Model. Earth Syst., 2021. S. Song, Y.-L. Hwong, S. C Sherwood, A. Stirling, C. Rio, R. Roehrig, C. L. Daleu, and R. S. Plant. Characterising Convective Schemes by Their Linearised Responses, 2019. Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA
Start Year 2019
 
Description Multi-institute collaboration to test convection parameterizations 
Organisation University of Toulouse
Country France 
Sector Academic/University 
PI Contribution The collaboration is a multi-institute group led from the University of New South Wales to assess the linear response characteristics of a wide range of convection paramterizations subjected to perturbed forcings.
Collaborator Contribution As noted above
Impact Single discipline - Meteorology. Outputs: Y. L. Hwong, S. Song, S. C. Sherwood, A. J. Stirling, C. Rio, R. Roehrig, C. L. Daleu, R. S. Plant, D. Fuchs, P. Maher, and L. Touzé-Peiffer. Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations. Submitted to: J. Adv. Model. Earth Syst., 2021. S. Song, Y.-L. Hwong, S. C Sherwood, A. Stirling, C. Rio, R. Roehrig, C. L. Daleu, and R. S. Plant. Characterising Convective Schemes by Their Linearised Responses, 2019. Poster at: AGU Fall Meeting, 9-13 December, San Fransisco, USA
Start Year 2019
 
Description A CPD session on representing convection in numerical weather prediction models 
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 A session was delivered for the Royal Meteorological Society Masterclass series which is primarlty intended to support CPD for professional meteorologists, in some cases helping them work towards registered or chartered status.
Year(s) Of Engagement Activity 2021
URL https://www.rmets.org/event/cpd-webinar-representing-convection-numerical-weather-prediction-models-...
 
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 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 Presentation at UKMO RMED Convection Working Group Meeting 10 June 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk by T Jones on "A Comparison of Vertical Level Set Choices for RCE in MONC and the Idealised UM"
Year(s) Of Engagement Activity 2021
 
Description Presentation at: EGU General Assembly 2020, Online, 4-8 May 2020 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk by D Shipley on "Multi-fluid single-column modelling of Rayleigh-Bénard convection"
Year(s) Of Engagement Activity 2020
 
Description Presentations at: 34th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society Virtual Meeting 10-14 May 
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 J F Gu on "Can Simplified Cloud Structures Capture Vertical Fluxes?" At the same meeting, a talk was also presented by C. Holloway on "The Key Components of Convection for Vertical Transport of Heat and Moisture: A Core-cloak Conceptual Model"
Year(s) Of Engagement Activity 2021
 
Description Presentations at: Conference on Improvement and Calibration of Clouds in Models, 12-16 April, Meteo-France, Toulouse, France 
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 C. Daleu on "Memory properties in cloud-resolving simulations of the diurnal cycle of deep convection". Also reporting on work from the project, a talk was presented by J-F Gu on "Pressure Drag for Shallow Cumulus Clouds: From Thermals to the Cloud Ensemble," a talk by S Hagos of PNNL on " A machine learning assisted stochastic cloud population model as a parameterization of cumulus convection", and a talk from Y-L Hwong of UNSW on " Characterising Convection Schemes Using Their Linearised Responses to Convective Tendency Perturbations"
Year(s) Of Engagement Activity 2021
 
Description Presentations at: EGU General Assembly, 19-30 April 2021, Vienna, Austria, online 
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 C Daleu on " Memory properties in cloud-resolving simulations of the diurnal cycle of deep convection". Also a talk was presented by J-F Gu on "Pressure drag for shallow cumulus clouds: from thermals to the cloud ensemble" and a talk by C Holloway on "Composited structure of shallow cumulus clouds"
Year(s) Of Engagement Activity 2021
 
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 Todd Jones describing work on Radiative Convective Equilibrium Across the Gray Zone
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
A poster was presented by Dan Shipley describing work on Multi-fluid modelling of Rayleigh-Bénard convection at grey zone resolutions
Year(s) Of Engagement Activity 2019
URL https://sites.exeter.ac.uk/convection-workshop/
 
Description Talk at: Finite Volumes for Complex Applications IX workshop, 15-19 June 2020, Bergen, Norway, online. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk on on Multi-fluid modelling of atmospheric convection by H Weller, W McIntyre and D Shipley
Year(s) Of Engagement Activity 2020
 
Description Talk by J-F Gu in "Weather and Climate Discussion" at Department of Meteorology, University of Reading 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Dr Gu presented a talk describing the project research on "Pressure drag for shallow cumulus clouds: from thermals to the cloud ensemble" as part of the department's weekly "Weather and Climate Discussion". The sessions are open to all staff and students in the department but are primarily aimed to be informal and accessible for students.
Year(s) Of Engagement Activity 2020