AMMA promoted international coordination of ongoing activities,
basic research and a multi-year field campaign over West Africa
and the tropical Atlantic.
close partnerships between those involved in basic research of the
WAM, operational forecasting and decision making, and it has
established blended training and education activities for African technical
institutions and schools.
Beginning 2006, scientists
from more than 25 countries, representing more than 140 national and
pan-national agencies and institutions are involved in AMMA. The number
of active scientists is in the order of 400 to 500. A network
of African scientists linked to AMMA has been established (AMMANET or AMMA
Africa) which help to consolidate existing collaborations in Africa and
to federate initiatives through a pan-African partnership.
Exhaustive list of
the laboratories carrying out the research work of AMMA.
Funding of AMMA
AMMA was initiated
by an international scientific group and is currently funded by a large number
of agencies, especially from France, UK, US and Africa with a major contribution
from the European Community's 6th Framework Research Programme. Other international
efforts are underway to help mobilise the extra funding needed to achieve all
the AMMA aims.
List of the funding
organisations of AMMA.
Endorsement of AMMA
AMMA is endorsed
by the World Climate Research Programme (WCRP)
and continues to develop in association with CLIVAR
and GEWEX .
AMMA has also been
endorsed by two projects within International Geosphere-Biosphere Programme
IGAC and ILEAPS.
AMMA is working with
other international projects and programmes to achieve its aims including GCOS,
GOOS and THORPEX.
We are currently
hindered in providing skillful predictions of WAM variability and its impacts.
There are still fundamental gaps in our knowledge of the coupled atmosphere-land-ocean
system at least partly arising from lack of appropriate observational datasets
but also because of the complex scale interactions between the atmosphere, biosphere
and hydrosphere that ultimately determine the nature of the WAM. The monitoring
system for the WAM and its variability is inadequate with many gaps in the standard
routine network and lack of routine monitoring of some key variables. While
the next generation of satellites will undoubtedly help with routine monitoring
and prediction efforts, more research is required to validate and exploit these
data streams. Dynamical models used for prediction suffer from large systematic
errors in the West African and tropical Atlantic regions; current models have
problems simulating fundamental characteristics of rainfall such as the diurnal,
seasonal and annual cycles. Finally, there is a lack of integrative science
linking the work on WAM variability with work on food, water and health impacts.
More effort needs to be made to integrate scientists working in these different
for a research project concerned with WAM variability and predictability comes
from recognizing the role of Africa on the rest of the world. Latent heat release
in deep cumulonimbus clouds in the ITCZ over Africa represents one of the major
heat sources on the planet. Its meridional migration and associated regional
circulations impact other tropical and midlatitude regions, as is exemplified
in the known correlation between West African rainfall and Atlantic hurricane
frequency. In addition to the large-scale interactions, we know that a majority
of hurricanes that form in the Atlantic originate from weather systems over
West Africa; however we know little about the processes that influence this
and why only a small fraction of these "seedlings" actually become
The WAM system provides
an ideal framework for considering scale interactions in a monsoon system: it
possesses pronounced zonal symmetry with characteristic jets and associated
well-defined weather systems. Research on such scale interactions and in particular
those linking dynamics and convection with the land surface will be relevant
to other monsoon systems and is needed in order to improve coupled atmosphere-ocean-land
models used for weather and climate prediction. In order to carry out this research
extra observations are needed.
West Africa is also
an important source region for natural and anthropogenic emissions of precursors
to key greenhouse forcing agents (e.g. ozone, aerosols). For example, Africa
contributes around 20% of the global biomass burning fires. These emissions
are modulated by the activity of the WAM but in contrast to other surface impacts
they feedback directly on the climate. Long-range transport of trace gases out
of West Africa has important implications for the global oxidizing capacity
of the atmosphere (which controls the level of many greenhouse gases), global
climate change and the transport of key constituents (e.g. water vapour, ozone
depleting substances) into the stratosphere. The fires also produce huge quantities
of particles, complex mixtures of organic materials and black carbon.
Tropical Africa is
the world's largest source of atmospheric dust. Both the fire aerosols and dust
play a major role in radiative forcing and in cloud microphysics, and thus are
an important part of WAM system. A key priority is to determine the transport
of trace gases and aerosols from the surface to the upper atmospheric layers
and the subsequent transport by the WAM. It is thus necessary to study the dynamics
and the chemistry of the atmosphere in the same framework.
The AMMA Programme
A project that deals
with all the major issues raised above require a major coordinated international
effort involving a multidisciplinary approach to the West African monsoon linking
observations, data analysis and modeling on a wide range of space and time scales.
To address the multiple
scales that characterize the WAM the program is structured around 4 interacting
spatial scales (see schematic below):
(i) Global scale. This is the scale at
which the WAM interacts with the rest of the globe; emphasis is given to improving
our understanding of the role of global SST patterns on WAM variability; seasonal-to-decadal
variability are the main time scales of interest
(ii) Regional scale. This is
the scale at which we consider monsoon processes and scale interactions; emphasis
is given to improving our understanding of the interactions between the atmosphere,
land and tropical Atlantic ocean (especially the Gulf of Guinea). It is important
to study the role of land surface feedbacks on variability of the WAM at this
scale including the key roles of vegetation and soil moisture. The annual cycle
and seasonal-to-interannual variability are the main time scales of interest.
(iii) Mesoscale. This is the scale of the typical rain-producing weather systems
in the WAM. It is central for studying the variability of rainfields at the
seasonal scale and the coupling between hydrology and the atmosphere at the
(iv) Local scale
or sub-meso scale. From an atmospheric point of view, this is the convective
rain scale; it is central to the hydrology of the Sahel and of small watersheds
to the south; it is the main scale of interest for agriculture.
schematic of key phenomena together with their associated space and time scales.
The arrow is included to highlight the importance of scale interactions and
transport processes in the WAM.
AMMA emphasizes the
importance of improved understanding of how these scales interact and combine
to characterize the WAM and its variability, including how these interactions
impact sources and transport of water vapour, aerosol and key chemical species
(e.g. key greenhouse gases, ozone and aerosol precursors) in the West African
region and globally.
Science and Implementation of AMMA
Key objectives and
planned research activities for each scale have been formulated for AMMA. While
it is convenient and appropriate to describe the research plans in terms of
these different spatial scales, it is essential for an improved understanding
to study the scale and process interactions. The implementation of AMMA is designed
in this spirit. The AMMA project integrates the scales at which the geophysical
and human processes interact. Furthermore the various disciplines involved in
the study of the West African Monsoon need to be integrated to achieve the three
overarching aims. This approach has guided the structuring of the scientific
of AMMA: Integrative
science for the geophysical (a) and human dimension (b) Integration from this
knowledge through various tools and for the exploitation by impact studies (c)
From the geophysical
perspective, the fundamental science underpinning the AMMA project can be
viewed as the various disciplines coming together within broader integrative
interactions between the WAM and global climate from a physical as well as
a chemical perspective,
ii) the water
cycle of the WAM from the regional to the local scale and
coupled atmosphere-land-ocean system and its multiple scales.
To feed these integrative
topics with sound disciplinary knowledge of the processes and their
scale dependence detailed studies of the processes are needed:
processes with a focus on the convective processes which are key to the rainfall
processes as they contribute and depend on the WAM,
processes over the continent from the regional to the local scale and
and chemical processes in the atmosphere.
To study the human
dimension of the variability and possible trends in the West African Monsoon
AMMA aims to address the direct impact of the environmental conditions
on three limiting conditions for the African societies:
iii) health impacts.
This activity will
be coordinated to achieve a better understanding of how weather and climate
variability impact food security and human processes in the region.
To achieve the AMMA
scientific objectives and to master the challenge of multi-scale and
multi-disciplinary aspects, a consistent set of tools and methods
adapted to the problem of the West African Monsoon will be used:
and data assimilation,
ii) field campaigns,
iii) satellite remote sensing and long-term atmosphere/land/ocean data collection
iv) data base.
are key to transferring knowledge from the geophysical community in AMMA to
the activities in the human dimension. These tools will collect and consolidate
knowledge, integrate the knowledge and materialize the predictive skill gained
with this knowledge.
AMMA is planned to
be a multi-year project and involves 3 nested observation periods. It should
be underlined here that the enhancement of observations during these periods
has provide a unique opportunity to determine future operational monitoring
necessary to improve weather and climate forecasts over the West African region.
More than this, a high priority for AMMA is to establish this operational network
of observations providing a visible legacy for the international AMMA programme.
strongly contribute to the objectives of the project by providing key variables
of the surface - atmosphere system (e.g. Meteosat/MSG,
TERRA). AMMA provides a unique set of integrated
atmosphere/land/ocean observations for validation of the satellites. It
also provide the framework to build a reliable monitoring strategy combining
satellite and in situ atmosphere/land/ocean networks, to make up for the low
density of routine observations in and offshore Africa. Geophysical parameters
and their uncertainties will be produced at different scales and gathered in
a unique database allowing multiscale as well as multidisciplinary analysis
of the WAM and its variability.
Climate Prediction Models
Models have been combined
with observations to investigate the nature of the WAM at daily, seasonal-to-interannual
and decadal timescales, including how the different scales interact. As throughout
the AMMA program, the linkages between weather and climate variability have
been emphasized. This approach is particularly pertinent to improving models for
climate prediction since scale interactions and processes not handled well by
GCMs used for climate predictions are best studied in the same GCMs at the weather
system scale. Thus, while AMMA recognizes the need for different modeling strategies
for studying and predicting weather and climate variability, it seek to
develop a strong synergy between them especially with respect to understanding
representation of key scale interactions and systematic errors.
AMMA has been carefully
conceived to improve our fundamental understanding of the West African monsoon
and its societal impacts and to make sustainable improvements to monitoring
and prediction of the West African environment. Our activities are embedded
within a 'Long-term observing period' (LOP) structure, which will ensure that
our intensive activities are directed towards systematic improvements in monitoring
and prediction over the coming decades. We will develop and upgrade two important
land-based atmospheric monitoring systems (for the upper air and surface fluxes),
and over the LOP we will transfer responsibility for these networks to the local
African agencies. In addition, ocean monitoring systems surrounding West Africa
that have been shown to improve both weather and climate forecasts will continue
to provide data to these groups. These networks of observations are of enormous
value both to global prediction systems and to local forecasting systems, based