GEMS is developing comprehensive monitoring and forecasting systems for trace atmospheric constituents important for climate and air quality. The systems will provide the basis for value-added data and information services to be developed as part of Europe's Global Monitoring for Environment and Security (GMES) initiative. These services will:
- provide global data in support of conventions and protocols on climate change, depletion of stratospheric ozone and long-range transport of atmospheric pollution;
- provide information in support of development and implementation of European environmental policy;
- address areas of key uncertainty in climate forcing identified by the Intergovernmental Panel on Climate Change (IPCC);
- provide improved operational air-quality forecasts and a means for assessing the impact of climate variability and change on regional air quality;
- provide improved monitoring and forecasting of UV radiation and solar-energy resources;
- support downstream services for end-users;
- complement the weather and climate services provided by the European Meteorological Infrastructure.
GEMS builds on the global weather forecasting system operated by the European Centre for Medium-Range Weather Forecasts. ECMWF and its partners in the project have added a capability for analysing and modelling the distributions of key greenhouse gases, chemically reactive gases and aerosols. The resulting integrated system is capable of assimilating a wide range of observational meteorological data, associated ocean-wave and land-surface data, and the increasing amount of remotely sensed data on atmospheric trace constituents that has been provided by satellites in recent years. Ground-, aircraft- and balloon-based constituent measurements are used for validation. The system is being run to reconstruct global conditions day-by-day over the past five years, and routine daily running provides real-time monitoring and forecasts of conditions for several days ahead.
The broad-scale air-quality products of the global system are complemented by products from an ensemble of finer-resolution forecasts generated by ten regional air-quality models that have been adapted to run over a common European domain. These regional models use common meteorological driving conditions from ECMWF's operational weather forecasts and take lateral boundary values of trace constituents from the global GEMS system. This ensemble system is run daily, and is also being used in studies of particular events from the extreme year of 2003.
Other studies within GEMS include utilization of the global analyses to refine estimates of the surface sources and sinks of greenhouse gases, and assessment of the value of derived products related to human health.
GEMS is organized in six interacting themes. The project is coordinated by Adrian Simmons on behalf of the European Centre for Medium-Range Weather Forecasts (ECMWF) and involves 31 other partner institutions from 13 countries. GEMS began in 2005 and is funded until mid 2009 by the European Commission as part of its Sixth Framework Programme, under contract number SIP4-CT-2004-516099.
GEMS owes a great debt of gratitude to Tony Hollingsworth, who conceived the project and was its coordinator until his death in July 2007.