Lead Research Organisation: University of Reading
Department Name: Meteorology


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.
Description The Indian Ocean Dipole - a system of varying sea-surface temperatures in the Indian Ocean - is known to exert a strong control on rainfall in East Africa between October and December. Our research examines the climate models used in the most recent IPCC assessment report and finds that a model's ability at capturing the connection between East African rainfall variations and sea surface temperature patterns is governed by its overall simulation of the current climate. Around half of the models studied are found to have winds from the east, across the Indian Ocean, that are too strong. These winds feedback onto the ocean surface temperatures and are amplified, resulting in too much moisture being carried to East Africa at this time of year. This results in the models having too much rain in the October-December season. The implications of this study are that further effort is needed to understand ocean-atmosphere processes over the Indian Ocean, in order to gain a better representation of climate in East Africa, and thereby have greater confidence in seasonal forecasts or climate projections for the region.

The seasonal cycle of rainfall over southern West Africa is characterised by a mid-summer dry period, interrupting the summer monsoon rains. Unfortunately, this is misrepresented in the coupled models of the ocean and atmosphere that are often used to inform IPCC climate projections, limiting our confidence in these projections. Work has shown (Wainwright et al.) that these biases in rainfall stem from errors in sea-surface temperature in the tropical Atlantic Ocean, which feed-back on the seasonal cycle of rainfall and cause it to be too wet in mid-summer. The implications of this study are that further effort is needed to understand and remove coupled ocean-atmosphere errors over the Atlantic Ocean in order to improve confidence in future climate projections for West African rainfall.
Exploitation Route These results can inform future climate model deveolpment and intepretation of climate change predictions or seasonal forecasts
Sectors Environment

Description Oral presentation at the "Good Hope for Earth Sciences" joint IAPSO-IAMAS-IAGA assembly, 27 August-1 September 2017, Cape Town, South Africa 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral presentation given by PDRA Dr Linda Hirons at the "Good Hope for Earth Sciences" joint IAPSO-IAMAS-IAGA assembly, 27 August-1 September 2017, Cape Town, South Africa in session JM 4 - FUTURE CLIMATE FOR THE AFRICAN CONTINENT (IAMAS and IAPSO). Presentation title, "Large-scale drivers of variability in the East African short rains" on Monday 28 August.
A publicationin an ISI journal eventually developed out of this work: "The impact of Indian Ocean mean-state biases on the representation of the East African short rains"
Year(s) Of Engagement Activity 2017