The dual setup of IAGOS aims at providing global-scale coverage of key observables on a day-to-day basis with a more complex set of observations with reduced coverage. The IAGOS-CORE component comprises the implementation and operation of autonomous instruments installed on long-range aircraft of several internationally operating airlines for continuous, global-scale and daily measurements of reactive gases, greenhouse gases (e.g. CO2, CH4), aerosol and cloud particles. The IAGOS-CARIBIC component consists of a heavily modified cargo container equipped with instruments for a large suite of trace gases and aerosol parameters, which is deployed once per month for four intercontinental flights. At present 8 aircraft are equipped with IAGOS-CORE instrumentation and one aircraft carries the IAGOS-CARIBIC container. At the end of its Construction Phase,

IAGOS aims for an operational fleet of up to 20 equipped passenger aircraft. IAGOS contributes to improved understanding of climate change and global air quality by providing regular in situ observations on a scale and in numbers that would be impossible to achieve using research aircraft and for which other measurement methods (e.g. satellites) have technical limitations. This input is essential for climate research, emissions monitoring, weather prediction and air quality forecasting. Data is provided for climate models, including those used by the Copernicus Atmosphere Monitoring Service, and for the carbon cycle models employed for the verification of CO2 emission and Kyoto monitoring. Regional air quality models will assimilate IAGOS near real-time data to improve forecasts. IAGOS data are also utilised for the calibration and validation of satellite sensors. Cooperation with aviation industry and instrumentation developers aims at designing strategies to deal with the observation of ice particles and dust, including volcanic ash and their operational consequences.