Community Research and Development Information Service - CORDIS

Periodic Report Summary 2 - PREFACE (Enhancing prediction of tropical Atlantic climate and its impacts)

Project Context and Objectives:
The tropical Atlantic climate recently experienced shifts of great socio-economic importance. The oceanic changes were largest in the eastern boundary upwelling systems, globally important regions for marine productivity and climate. African countries bordering the Atlantic depend upon their ocean for societal development, fisheries, and tourism. They were strongly affected by these changes and face important adaptation challenges associated with global warming. Unfortunately, the tropical Atlantic is a region of key uncertainty in the climate system: state-of-the-art climate models exhibit large systematic errors, prediction of climate variability and climate change are highly uncertain, and how shifts in climate impact marine ecosystems is largely unknown, as are their possible global socio-economic impacts.
To redress this situation, PREFACE joins European and African expertise to provide the first comprehensive assessment of the tropical Atlantic. In four research foci, sophisticated observation systems, extensive field experiments, regional and global scale modelling capabilities, and socio-economic marine ecosystem models are combined to improve the prediction of tropical Atlantic climate and its impacts.
The first research focus – Role of ocean processes in climate variability – aims to better understand the oceanic processes affecting sea surface temperature (SST) in eastern tropical Atlantic upwelling regions on seasonal to decadal time scales, by using historical and new data as well as medium to very-high resolution forced ocean models. We focus on the mixed layer heat and freshwater budgets, the tropical Atlantic circulation, and the equatorial and coastal wave response. By evaluating the ocean models, we will suggest improvements to reduce biases (systematic errors) in ocean and coupled climate models.
Evaluation of current climate models and reduction of model bias is the second focus, aiming to better understand and subsequently reduce systematic errors in climate models in the tropical Atlantic. Our strategy is to analyse the development of model systematic error in climate predictions and then perform coordinated, multi-model sensitivity experiments to identify the key processes that require improved model representation to mitigate these systematic errors. Additionally, we aim to understand the relation among errors in variability, feedbacks, and atmospheric-links to other regions of the globe.
Our third focus – Climate prediction in the Tropical Atlantic – aims to clarify the mechanisms for climate variability and predictability on seasonal to decadal time scales, by analysing observations and numerical experimentation. We also investigate interactions between the Atlantic and other regions, and both natural and anthropogenic factors. The goal is to improve the prediction of tropical Atlantic climate, and to assess the impact of model systematic error on prediction skill. We are developing a unified statistical prediction framework, and will also use state-of-the-art climate prediction models.
PREFACE’s last research focus – Impacts of climate change on pelagic functional diversity in the tropical Atlantic with effects on western African fisheries economies – aims to disentangle environmental and anthropogenic pressures on pelagic fish stocks in the tropical Atlantic, through exploratory analysis of historical and newly collected data. We also aim to better understand climate change effects on small-scale fisheries and coastal communities, and to assess uncertainties and implications for management. Our approach is to develop socio-economic models, built on knowledge of the marine ecosystem and fishing communities, and to drive them with climate change projections.
PREFACE envisions a closer cooperation between European and West African partner institutions leading to enhancement of research capacities in the fields of ocean physics, ecosystem and fisheries as well as climate research in West Africa.

Project Results:
PREFACE has advanced significantly towards its overarching goal to enhance prediction of tropical Atlantic climate and its impacts.
Key oceanic processes in the tropical Atlantic were better understood, by enhancing and analysing observations along the equatorial and coastal waveguides, and by numerical experimentation. We showed that eddy advection is important for the seasonal heat budget in the Benguela region, and large-scale advection is important for the Gulf of Guinea salt budget, and we quantified the impact of wind-excited near-inertial waves and chlorophyll-induced turbidity on the heat budget. Our ocean current measurements identified pronounced semi-annual, annual and interannual variability of the equatorial zonal flow linked to equatorial basin modes, and they allowed the first quantification of the seasonal cycle of the southward Angola Current. Our model studies indicate that the warm SST bias could be reduced close to the coast by both increasing the ocean model resolution up to 1/10° and using improved atmospheric forcing. Close cooperation between different European and African partner institutions were established or improved resulting in common experiments at sea, data sharing and analysis, as well as application of ocean modelling on regional scale.
PREFACE has identified key causes of systematic error in the tropical Atlantic in climate models. In general, atmospheric model errors are the dominant cause of the large equatorial and southeastern Atlantic SST biases, but the relative roles of wind, cloud-radiative and ocean dynamics differ regionally, seasonally, and among models highlighting the importance of a multi-model approach. The value of increasing model resolution is unclear, but it can significantly improve the simulation of tropical Atlantic climate. In addition, remote radiative errors from Southern Ocean can drive tropical biases. Reducing model biases through statistical corrections or new model configurations improves the simulations of SST variability, reducing the dominance of thermodynamic processes and enhancing the role ocean dynamics.
PREFACE has improved understanding of tropical Atlantic variability and predictability. We showed that interannual variations in equatorial Atlantic SST are linked to the South Atlantic Anticyclone, and their character and impact are modulated by Atlantic multidecadal variability. Climate models despite their large biases, capture the Atlantic Niño’s impact on the Pacific, and show that it likely enhanced El Niño variability after the 1970's; and some seasonal forecast systems can now predict Atlantic Niño events from May. We showed that Atlantic and Pacific decadal variability and global warming impact African and South American rainfall. Decadal variations in Sahel rainfall can now be predicted based on Atlantic SST. The large uncertainty in future evolution of the West African Monsoon is related to surface temperature and tropospheric winds. Lastly, advanced statistical methods were developed to improve SST and rainfall predictions, and to account for model bias.
PREFACE is increasing understanding of the interrelation among marine ecosystems, climate variability and change, and fisheries; and of the socio-economic implications of future climate change. Data of several shipboard surveys, carried out with regional partners, and the EAF Nansen project archives provide more than two decades of data. These were used to investigate the relationship between climate variations and trends in the south- and north-eastern tropical Atlantic, and the distribution of small pelagic fish as well as acoustics scattering layers. Biological parameters of a key small pelagic species appear resilient to current climate change. Ecological-economic models applicable to African fisheries were compiled; and questionnaires were carried out to assess the economic and social situation of local fishing communities, and their vulnerability to climate driven changes in the ecosystem.

Potential Impact:
PREFACE is a bold and ambitious project that targets one of the marine regions that will be more affected by climate change and its consequences. The project will provide the first comprehensive, multidisciplinary assessment of the tropical Atlantic climate, from observations to predicting its socio-economic impacts.
PREFACE has drastically improved the ocean and climate observing system in the eastern Atlantic, allowing a continuous monitoring of tropical Atlantic variability and climate change. PREFACE has installed key moorings in the southern and northern coastal wave-guides, extended the PIRATA (Prediction and Research Moored Array in the Atlantic, network toward the eastern tropical South Atlantic. Exemplary is the deployment, in association with several laboratories across West Africa, of an oceanographic and meteorological measuring buoy in the heart of the Senegal-Mauritania upwelling. PREFACE is not only generating knowledge for the optimal design of the future network, but is helping to ensure the long-term sustainability of the network, by increasing awareness and developing required competence among regional players.
PREFACE will lead to an improved understanding of variability in both eastern boundary upwelling African regions and the Gulf of Guinea. Our targeted ocean model experiments and their comparison with observational provide detailed process-based understanding and long-term directions to improve ocean and climate modelling and prediction capabilities.
PREFACE shall contribute to a better understanding of the mechanisms and predictability of tropical Atlantic climate, and of its global impacts. This includes the mechanisms for seasonal to decadal variability, and assessing also the contribution of external forced climate change.
PREFACE will lead to enhanced climate modelling and prediction capabilities, on seasonal to centennial time scales. It will provide a detailed understanding of the causes of model systematic errors, develop strategies to reduce them, and quantify their impact on climate prediction. Our novel tools to diagnose model errors and their consequences provide new directions for the wider scientific community using multi-model ensembles.
PREFACE has developed advanced statistical methods and bias correction techniques to improve climate predictions. We have demonstrated skillful prediction of equatorial Atlantic SST and decadal shifts in Sahel rainfall. Such improved predictions can have major socio-economic benefits, including for ecosystem and fisheries management
PREFACE activities will result in a deeper understanding of the function of marine ecosystem so that climate driven shifts can be better predicted. For example, we have shown that the warming of the South Atlantic during the last three decades was associated with threefold increase and southward shift in Sardinella biomass. By coupling such knowledge to improved climate predictions, PREFACE will provide framework to potentially predict such changes in small pelagic fish distributions.
PREFACE will provide policy relevant guidance on sustainable development of West African fisheries in the context of climate change. Knowledge gained of local fishing communities, better understanding of climatic and anthropogenic influences on marine ecosystems, and improved predictions will together lead to improved ecological-economic models and predictions for the region.
PREFACE shall lead to enhanced cooperation between European and African researchers working on tropical Atlantic climate and its impacts, by fostering existing collaborations and improving project synergy.
PREFACE is helping to train a new generation of researchers, including those from the region. Its summer schools, targeted workshops, and interdisciplinary meetings are providing the required education to continue important research on the tropical Atlantic climate and its impacts.

List of Websites:

Reported by

Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top