The AMMA field campaigns: Multiscale and multidisciplinary observations in the West African region

AMMA - the African Monsoon Multidisciplinary Analysis - is the biggest programme of research into environment and climate ever attempted in Africa. AMMA has involved a comprehensive field experiment bringing together ocean, land and atmospheric measurements, on time-scales ranging from hourly and daily variability up to the changes in seasonal activity over a number of years. Many of the publications in this special issue make use of subsets of the AMMA measurements, collected from a diverse set of sensors. As a general introduction to the special issue, this paper provides a comprehensive overview of the AMMA observational programme, and summarises the scientific strategy which has defined the field deployment. The relationship between the existing observational monitoring networks of the region and the new sensors deployed for AMMA, and for the future, is described. Making use of regional and sub-regional maps, the main groups of sensors are described in terms of their deployment periods and their spatial co-ordination. The key linkages between different groups of measurements are also outlined, in terms of the strategy for their combined use and in terms of their interdependence. Some brief summaries of conditions sampled during the three years of the AMMA Extended Observing Period are also given.