MACC - Monitoring Atmospheric Composition and Climate - is the project that is establishing the core global and regional atmospheric environmental services delivered as a component of Europe's GMES initiative. It is funded under the Seventh Framework Programme of the European Union and began on 1 June 2009. MACC is undertaken by a consortium drawn largely from the partners in the earlier GEMS and PROMOTE projects, whose core systems and service lines provided the starting point for MACC.

MACC takes as its input comprehensive sets of satellite data from many tens of instruments supplying information on atmospheric dynamics, thermodynamics and composition, made available by space agencies and institutions with which the agencies collaborate to produce retrieved data products. The satellite data are supplemented by in-situ data from meteorological networks and a limited amount of data from networks providing in-situ measurements of atmospheric composition. Data are processed to provide a range of products related to climate forcing, air quality, stratospheric ozone, UV radiation at the earth’s surface and resources for solar power generation. Additional in-situ data are used for validating the processing systems and the products they supply. MACC operates a value-adding chain which extracts information from as wide a range of observing systems as possible and combines the information in a set of data and graphical products that have more complete spatial and temporal coverage and are more readily applicable than the data provided directly by the observing systems.

The products delivered or under development by MACC are based on the requirements established for the core atmospheric component of GMES. They emanate from:

• Global service lines providing:
  • monitoring of aspects of climate, climate forcing and the sources and sinks of key species;
  • monitoring of stratospheric ozone;
  • forecasts of reactive gases and aerosols;
  • boundary conditions for regional models.

• European service lines providing:
  • air quality forecasts from high-resolution regional systems;
  • air quality assessments based on retrospective running of the regional systems using validated observational data;
  • UV radiation assessments and forecasts;
  • solar-energy resource assessments and forecasts.

• Service lines for policy development, including establishment of effective dialogue with the European Environment Agency, national and regional environment agencies and EMEP, so that MACC can shape its programme to support their work. Activities include:
  • agreements on data exchanges;
  • preparation of scenarios to be run on demand in unusual or emergency situations;
  • sensitivity studies to take better account of the effects of large cities in such scenarios;
  • development of a new adjoint approach to documenting source-receptor relations;
  • provision of agreed input to the EEA State of the Environment report;
  • preparations for downstream services.

Although the primary application of boundary conditions from the global system is in support of the regional models run for Europe as part of MACC, they may also be used to drive other models for the European region or models for other regions of the world. MACC includes a service-chain test case involving use of a regional model to study links between dust outbreaks and meningitis in the Sahel region of Africa. Other service-chain test cases are evaluating the capability of MACC’s core service lines to support downstream services for urban air-quality forecasting and other types of health warning.

The building blocks of MACC are a set of components with specific functions that are grouped into four clusters. The input data cluster acquires the satellite and in-situ observations and carries out preparatory processing of them. It also provides improved estimates of surface emissions of key species, with a particular emphasis on the highly variable emissions from fires. The primary global and regional clusters operate and refine processing systems that include not only the data assimilation and modelling elements that provide the basic monitoring and forecasting products, but also the elements that provide estimates of climate forcing, inferred corrections to the modelled sources and sinks, and derived products such as UV radiation and resources for solar power generation. An outreach cluster provides the interface to downstream-service providers and other users, runs the service-chain test cases and supports the development of policy for the control of atmospheric pollution.