2416 December 2004
IGOS Atmospheric Chemistry Theme
Integrated Global Atmospheric Chemistry Observations (IGACO)
Implementation Up-date Dec 2004
Leonard Barrie
Atmospheric Research and Environment
Programme
World Meteorological Organization
7 bis, avenue de la Paix, BP2300,CH-1211
Geneva, Switzerland
Email: Lbarrie@wmo.int
Jörg Langen
Earth Observation Science and Applications
Department
ESA-ESTEC, POB 299, NL-2200AG
Noordwijk, The Netherlands
Email: Joerg.Langen@esa.int
On 27 May 2004, the IGOS-partners approved the Atmospheric Chemistry Theme Report
assessing the past, present and future current state of global air composition observations, the
requirements and priorities in the next 15 years for Integrated Global Atmospheric Chemistry
Observations (IGACO) (see Figure 1). The IGACO report prepared by an expert international
group convened by the World Meteorological Organization (WMO) and the European Space
Agency (ESA) was reviewed independently by eminent scientists including two nobel prize
winners. IGACO is a highly focused strategy for bringing together ground-based, aircraft and
satellite observations of 13 chemical species in the atmosphere using atmospheric forecast
models that assimilate not only meteorological observations but also chemical constituents. Socioeconomic issues related to climate change, ozone depletion/ UV increase and air quality benefit by
having such a system in place.
Figure 1 A schematic of IGACO components, partners and links societal needs and
issues.
2416 December 2004
The IGACO report critically assesses, the requirements on accuracy/precision and spatial/temporal
resolution, and the current state of modelling chemical cycles in forecast and climate models. It
recommends specific steps to be taken in a phased approach over the next 15 years led by the
WMO Global Atmosphere Watch (GAW) programme in cooperation with other key WMO
programmes, the space agencies and the global air chemistry/meteorology/climate research
community.
In June 2004, the IGACO approval by IGOS and suggestion for WMO lead in implementation was
presented to the WMO Executive Council by the President of the WMO Commission on
Atmospheric Science (CAS). Implementation involves utilizing the over-arching plan of IGACO to
build the system through key collaborative initiatives supported regionally but having global
implications. Maintenance of existing observations, addition of key missing observations and
development of mechanisms that glue the system together are major but feasible challenges.
IGACO is a framework through which atmospheric composition observations can be integrated
using research and operational atmospheric models to contribute to the goals of IGOS-partners
and the planned Global Earth Observations System of Systems.
A tentative organizational structure for the implementation that is currently under consideration
brings specific bottom-up activities supported at the national, regional and international level
together with top-down support at the highest level. Already major European, North American and
Asian and southern hemispheric initiatives are being informed of IGACO and mutually beneficial
activities explored.
Figure 2 Schematic of the proposed structure for implementing IGACO