IMPALA: Improving Model Processes for African cLimAte

Lead Research Organisation: University of Leeds
Department Name: School of Earth and Environment


IMPALA will deliver a step change in global model climate prediction for Africa on the 5-40 year timescale by delivering reductions in model systematic errors, resulting in reduced uncertainty in predictions of African climate and enabling improved assessment of the robustness of multi-model projections for the continent. IMPALA will include key foci on continental convection and land-atmosphere coupling as fundamental drivers of local rainfall, and oceanic convection and aerosols as influencing global modes of variability and the teleconnection pathways by which they drive rainfall over various parts of the continent. Convection, land-atmosphere coupling and aerosols have been identified in the DFID/Met Office Climate Science Research Partnership (CSRP) as first order drivers of African rainfall and processes where contemporary models show significant uncertainties and biases.

IMPALA will use a single multi-temporal, multi-spatial resolution model, the Met Office Unified Model (MetUM), to allow rapid pull through of improvements made in the project into improved African climate modelling capability although the methodology and understanding will be widely applicable across all contemporary models. We will work through a pan-Africa lens to develop a benchmark suite of metrics targeted on key processes and user-relevant variables and will use the most relevant observations from past and future campaigns and latest remote sensing data. Strong links to partners and Regional Consortia (RC) will facilitate two-way evaluation and feedback, ensuring local understanding of relevant climate processes and required climate information in the regions. Evaluation of the impacts of the global model improvements, developed both within the project and through gearing from the ongoing model development process at the Met Office will be tested in idealised-scenarios of climate change.

The unique capability of the MetUM to run across a broad range of spatial and temporal scales will be central to the project. Running the MetUM as a cloud-resolving weather model, through to a multi-decadal climate model, will allow evaluation of physical processes controlling the uncertainty in key metrics of pan-African climate variability and climate change on the 5-40 year time scale. The latest global coupled models available at the Met Office will be harnessed to drive a higher resolution (4km) convection-permitting regional model, for the first time across the entire African continent, under both current and idealised future climates. This will deliver understanding of the roles played by improved local representation of convective processes and high impact weather on the climate variability and change over the continent and be used to improve convective, land-atmosphere coupling and aerosol parametrizations in the coarser-scale models. The results will also provide an important new resource for RC and other African-focused climate research, enabling better-informed evaluation of the robustness of multi-model projections. This, in turn, can be utilised by decision makers to improve risk management for health, agriculture and water resources and help protect the livelihoods of the most vulnerable, safeguarding societal development already achieved.

Key model results, metrics and observations will be made available to the FCFA RC and local partners through an interactive webpage. The consortium will also work closely with the FCFA Coordination, Capacity Development and Knowledge Exchange (CCKE) Unit in their pan-African cross-programme research activities.

Planned Impact

IMPALA research will have significant impact locally, nationally and regionally in Africa as well as globally via the following beneficiaries and pathways.
FCFA Regional Consortia adaptation and impacts researchers and regional climate information providers will have direct access to new scientific understanding on, and improved simulations of, African climate variability and change via inclusion in the established Africa-focused process evaluation group (PEG). CP4-Africa climate change simulations will be disseminated through the NERC JASMIN data cluster for regional consortia to test multi-model projection robustness in key stakeholder-relevant local processes and extremes often poorly represented in coarser resolution models.
Model development Scientists in Africa: The 5 African model evaluation and development scientists in IMPALA will make extended visits to the Met Office focused on MetUM evaluation, development and training. They and their institutes will be offered the opportunity to install MetUM technical infrastructure and support for its configuration and application, developing local and regional expertise which is currently in very limited supply.
Policymakers: Policy briefings on improved reliability of model predictions relevant to climate resilience and adaptation planning across Africa will be delivered to UK Government through DFID and, via the Met Office Hadley Centre Knowledge Integration team, DECC. Internationally they will be communicated to the Conferences of the Parties and the Nairobi Work Programme of the UNFCCC and IPCC through active engagement in its scientific assessments and special reports. Close contact will be maintained with the African Climate Policy Centre and the African Development Bank.
People and communities in Africa and beyond: The ultimate beneficiaries of the research will be people of sub-Saharan Africa and IMPALA scientists will work with the CCKE Unit to assist in generating cross-programme outputs, e.g. material demonstrating improved capability to assess risks of key agriculture-relevant rainfall events, for their user training workshops and interactions with other DFID programmes and broader capacity development and adaptation activities.
Operational weather, seasonal forecasting and climate service capability in Africa: IMPALA model developments will imply improved representation of processes important for short-range to seasonal forecasting. With the MetUM being used across all timescales these developments will rapidly deliver improved weather and seasonal forecasts relevant to existing severe weather to seasonal forecasting activities the Met Office is already feeding directly into as well as to future programmes such as SHEAR funded by DFID.
Scientific community, CMIP6 and other modelling centres: To broaden the Africa-lens approach to the international stage IMPALA's methodology for model diagnosis, understanding and improvement will be disseminated through papers, at international science meetings and included in the planned CMIP6 benchmarking and evaluation software tools (overseen by the WCRP Working Group for Coupled Models co-chaired by the PI).
Cross programme Activities: IMPALA scientists will work with the CCKE Unit to ensure full engagement in cross-programme activities and knowledge transfer through relevant networks. Scientists from regional consortia will be included in the Africa PEG to enable a rapid exchange of model developments, datasets and understanding and ideas on relevant metrics of model performance.
Wider FCFA programme activities through the Programme Executive Committee (PEC): The PI will work with the Programme Management Unit and PEC to increase IMPALA impact and reach beyond FCFA. The PI and CO-Is have broad experience in communicating work on African science to inter-disciplinary scientists and policy makers through their engagement in previous DFID or NERC projects and are already active in many outreach events in Africa.


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Roberts A (2018) Can explicit convection improve modelled dust in summertime West Africa? in Atmospheric Chemistry and Physics

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Garcia-Carreras L (2021) Capturing convection essential for projections of climate change in African dust emission in npj Climate and Atmospheric Science

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Smith C (2018) FAIR v1.3: a simple emissions-based impulse response and carbon cycle model in Geoscientific Model Development

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Pope RJ (2016) Identifying errors in dust models from data assimilation. in Geophysical research letters

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Tomassini L (2017) The interaction between moist diabatic processes and the atmospheric circulation in African Easterly Wave propagation in Quarterly Journal of the Royal Meteorological Society

Description We have tested the representation of rainfall in climate models, with differing representations of the weather systems.

From observations, we find a significant modulation of African rainfall by "Kelvin waves" propagating along the equator. The response of the rain is different in different locations due to local climate (e.g. topography, coastlines etc). We find that the type of model used in global prediction has a surprisingly good representation of the sensitivity of the rainfall to these prevailing weather conditions (Kelvin wave). However, its representation of weather extremes (heavy rain and drought) is much less successful: we indicate the causes of these errors.

We find that the global prediction models fail to capture the mechanisms causing changes in the rainfall distributions in the tropics in a changing climate. When the storms are resolved by a model, we find that a weakening tropical circulation is embedded with intensifying severe storms. The low resolution model cannot capture this behaviour, and its overall circulation-changes are biased as a result.
Exploitation Route The results are already being used by the Met Office as a measure of the capability of their models to capture the effects of global climate change on local high-impact weather in Africa.
Sectors Environment

Description We have implemented a new dust-uplift scheme in the Met Office Unified forecast model.
First Year Of Impact 2017
Sector Environment
Impact Types Economic

Description CEH-Leeds 
Organisation UK Centre for Ecology & Hydrology
Country United Kingdom 
Sector Public 
PI Contribution My team in Leeds conduct atmospheric studies using observations, models and theoretical ideas. I have also led a number of projects and field experiements in which we have collaborated with CEH.
Collaborator Contribution Expertise in land-surface processes. Expertise in land-atmosphere interactions. Expertise in land-atmosphere climate dynamics. Data analysis, especially remote sensing of rainfall and land surface state. Leadership of projects. Co-supervision of PhD students.
Impact This is a multidisciplinary partnership in the area of land-atmosphere interaction. It has resulted in a large number of high-impact papers, successful jointly-supervised PhD studentships, and successful impacts, especially in Africa.
Description Met Office 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Academic/University 
PI Contribution Our research group analyses atmospheric processes in order to better represent them in the Met Office's forecast models. We also use those forecast models in our research, and evaluate their performance in order to identify the best strategies to improve the models.
Collaborator Contribution The Met Office brings its models and its datasets to the partnership, in addition to the considerable expertise of its staff. The Met Office also represent a conduit to the impact of our research for society, through its provision of operational weather and climate forecasts.
Impact Our research has influenced the Met Office strategy for model development, especially in regard to high-resolution models, and the convective parametrisation scheme. We have jointly influenced international strategy for atmospheric research and measurements.