An international long-term collaboration to study the climatic and environmental feedback mechanisms involved in the African monsoon, and in some of its consequences on society and human health. The programme, which started in 2004, has developed a network of ground-based observation stations over Sub-Saharan West Africa to measure heat flux and, for some stations, CO2 and H2O vapour fluxes. Files also include concomitant meteorological measurements (wind, temperature, pressure, humidity, rainfall) and soil physics parameters (soil temperature and moisture). The UK branch of AMMA makes use of several instruments provided by the UK Universities Facility for Atmospheric Measurement (UFAM) which are centred on the Niamey meso-site. The Facility for Airbourne Atmospheric Measurements (FAAM) aircraft was used during the July-August 2006 campaign. This dataset contains data on the emission, biogenic and NOx tracers, temperature, humidity and pressure.

The Aerosol Direct Radiative Impact Experiment (ADRIEX) was a joint UK Met Office/Natural Environment Research Council (NERC)/UK Royal Society/University of Oslo project aiming at improving our understanding of the radiative effects of anthropogenic aerosol and gases (ozone and methane) in the troposphere. This dataset contains forecast trajectories computed using UTRAJ. The term “particle trajectory” describes the path of a point which is blown by a time dependent wind field (i.e. (u, v, w) as a function of (x, y, z, t)). Trajectories following the analysed wind field are described by their coordinates (e.g. longitude, latitude, pressure) at regularly spaced time intervals. “Domain filling” refers to calculations where the arrival points of back trajectories (or release points for forward trajectories) form a dense, regular grid in a specified volume. The term “reverse” is used to indicate that the particles are followed backwards in time. Back trajectories are assumed to arrive on a 3D grid consisting of a stack of horizontal grids (regular in longitude and latitude) on a range of pressure levels. Forward trajectories are assumed to depart from similar grids. The trajectory length (time before arrival for back trajectories) is denoted by the letter T. Other fields can also be recorded following the trajectories: for example, temperature, specific humidity or potential vorticity. These extra fields are described as “attributes” and will be denoted by the variable C. The change in the value of an attribute over the length of a trajectory is denoted by C(0) − C(T).