• RICE measured the effects of rice cultivation in increasing the concentration of atmospheric methane and other trace gases. It gained an understanding of variability of methane emissions in time and place.

• ACE-1, part of the larger ITCT initiative, was the first of a series of studies that analyzed the indirect effects of anthropogenic aerosols through cloud modification. ACE-1 took place from October to December 1995 across the Pacific Ocean and south of Australia. The experiment focused on the minimally polluted marine atmosphere, creating an opportunity to be able to study the natural aerosol system and its chemical, physical, and radiative and cloud nucleating properties.

• The Focus on Atmospheric Aerosols activity was initiated in 1995 as a result of the merging of the International Global Aerosol Program (IGAP) with IGAC. The principle objective was to improve understanding of the role of atmospheric aerosols in climate forcing and in the prediction of changes in global climate and geospheric-biospheric processes.

• GLOCHEM sponsored several campaigns including the Mauna Loa Observatory Photochemistry Experiment (MLOPEX). MLOPEX made concurrent measurements of the key species that play controlling roles in the photochemical transformation of ozone, odd nitrogen, and odd hydrogen species in the remote free troposphere. The results were published in JGR – Atmospheres. GLOCHEM also coordinated the Second Tropospheric Ozone (TROPOZ-II) activity, which measured chemically active gases in the free troposphere.

• The GHOST activity was implemented in 2003. Its premise was built upon the need to understand the chemical importance and distribution of OH in the troposphere as well as explore whether the level OH abundance is due to natural processes versus man made disturbances.

• GIM was formed as a merger project from the International Global Aerosol Program (IGAP) project MEARC in 1997 and was implemented under the IGAC Global Focus. GIM aimed to address the development and application of advanced 3-D global chemical transport and coupled climate and chemistry models, emphasizing tropospheric applications. It conducted a series of model intercomparison exercises focusing on key problems in tropospheric chemistry as well as collaborated with other modeling development efforts.

• GLONET was designed in 1996 to improve the quality of O3 profile measurements, and implant new stations in geographic regions critical for achieving global coverage. Also, through its sub-project International Tropospheric Ozone Years (ITOY), it began the establishment of a global database for validation of chemistry and transport models. The focus was directed towards expanding ozonesonde stations in tropical and subtropical areas. It conducted inflight intercomparison of ozone-sondes and airborne UV-photometers with the Jülich Ozone Intercomparison Experiment (JOSIE).

The primary objective of the SOLAS/IGAC task HitT is to determine and quantify the importance of reactive halogen compounds (RHCs) in tropospheric chemistry and climate forcing. Key themes are the influence of RHC on the oxidative capacity of the atmosphere, the ozone budget, as well as in aerosol nucleation and growth.

The primary goals of HESS were to estimate the strength of trace gas sources and sinks in high-latitude ecosystems on a global scale, determine the principal ecological and environmental correlations and understand the importance of them on environmental change. HESS conducted the Northern Wetlands Experiment campaign, which looked at the importance of Northern wetlands as sources of biogenic gases contributing to the atmosphere. The activity merged into BATREX in 1999.

Through ITCT, IGAC endorsed a series of research campaigns on intercontinental transport and chemical transformation. These tasks included three campaigns on aerosol characterization experiments (ACE-1, ACE-2, and ACE-Asia); the Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate Chemistry, Aerosols, and Transport (POLARCAT); participation in the New England Air Quality Study; and the ITCT-Lagrangian-2k4 experiment that was part of ICARTT.