Past Activities

Past IGAC activities and initiatives

In an effort to show some of the history of IGAC we have compiled a list or former IGAC activities and thier objectives/accomplishments. If you have any questions regarding a specific past activity or would like to learn more about a former IGAC activity, please contact Keep in mind that the following list is incomplete.

Archives of past activities briefs

Aerosol Characterization and Process Studies (ACAPS), 1996 - 2003 or earlier

  • ACAPS goal was to investigate and further understand the relationship of the chemical, physical, radiative and cloud nucleating properties of atmospheric aerosols. The focus was to determine the chemical, physical, and biological processes controlling the formation and fate of aerosols and how these processes affect the number size distribution, the chemical composition, and the radiative and cloud nucleating properties of aerosols.

Aerosol-Cloud Interaction (ACI), 1996 - 2003 or earlier

  • ACI sought to improve the understanding of the relationships between the physical and chemical properties of aerosols and the microphysical and radiative properties of the clouds that form du e to aerosol cloud condensation nuclei. Additionally, ACI studied the relationships between the physical and chemical properties of the aerosols that are processed or formed by clouds.

Aerosols, Clouds, Precipitation, & Climate (ACPC), 2007 - 2013

  • ACPC was established in 2007 to obtain a quantitative understanding of the interactions between aerosol, clouds, and precipitation and their role in the climate system. ACPC is a coordinated effort encompassing six strategic elements:
  1. a focus on regimes where there are strong indications of aerosol-cloud-precipitation interactions;
  2. an emphasis on statistical characterizations of aerosol-cloud-precipitation interactions;
  3. the development of approaches that leverage past and ongoing activities;
  4. thorough integration of modeling and observational activities;
  5. a hierarchical approach to both modeling and data collection/analysis; and
  6. continued development of measurement techniques

In addition, a new component of ACPC is the SAT-ACPC effort, which seeks to address specifically how satellite-based measurements can be used to improve the understanding of the role of aerosols in precipitations processes. ACPC is currently working to expand the GoAmazon2014 research field campaign sponsored by the U.S. Department of Energy. The Amazon Basin has strong coupling between terrestrial ecosystems and the hydrologic cycle. GoAmazon will provide the needed observations to study how aerosols and surface fluxes influence cloud cycles under clean and polluted conditions.

African Monsoon Multidisciplinary Analysis - Atmospheric Chemistry (AMMA-AC), 2002 - 2012

  • AMMA was an international project launched in 2002 to improve knowledge and understanding of the West African Monsoon, its variability, and its impact on West African nations. Phase one of AMMA came to a completion at the beginning of 2010 and findings were published in a Special Issue of Atmospheric Chemistry and Physics. AMMA-AC during Phase 1 focused on the development of measurement networks of trace gases and aerosols throughout West Africa.

Asian Pacific Regional Aerosol Characterization Experiment (ACE-ASIA), 2001

  • The Aerosol Characterization Experiments, part of the larger ITCT initiative, were designed to increase our understanding of how atmospheric aerosol particles affect the Earth’s climate system. The experiments were conducted in the spring of 2001 off the coast of China, Japan and Korea. This region was of particular interest because it is downwind one of the world's largest aerosol source regions on Earth. More information regarding the findings of ACE – ASIA can be found here.

Atmospheric Chemistry & Climate (AC&C), 2007 - 2012

  • Jointly sponsored with WCRP-SPARC, AC&C sought to improve the representation of chemistry/climate interactions in models. Activities within AC&C were coordinated with modeling activities such as SPARC’s Chemistry-Climate Model Validation Activity (CCMVal), the Aerosol Comparisons between Observations and Models (AeroCom) project, and the Task Force on Hemispheric Transport of Air Pollution (HTAP) to assure maximum efficiency in model runs, meeting planning, and resources. AC&C consisted of four efforts: Bounding the Role of Black Carbon in Climate, the Model Intercomparison Project (ACCMIP), Hindcast, and Vertical Distributions.

Atmospheric Chemistry and Environmental Education in Global Change (ACEED), 1995 - 2003 or earlier

  • The purpose of ACEED was to create an education and training program that would establish atmospheric chemistry programs at the undergraduate level in universities in developing countries. ACEED also sought to provide graduate research assistantships at cooperating universities with Ph.D. programs in atmospheric chemistry for qualified students from developing countries.

Biomass Burning Experiment: Impact on the Atmosphere and Biosphere (BIBEX), 1990 - ~2000

  • BIBEX was founded in 1990 with the primary mission to:
      Characterize the production of chemically and radiatively important gases and aerosol species resulting from biomass burning
      Assess the consequences of biomass burning on the regional and global scales
      Determine the short and long-term effects of biomass burning on the atmosphere
      Understand the biogeochemical consequences of atmospheric deposition of the products of biomass burning.

    BIBEX originally focused on biomass burning in the tropics, but in 1998 it became concentrated towards research on regional and global inventories, including remote sensing of fires, fire ecology, and global fire modeling. BIBEX contributed to the Experiment for Regional Sources and Sinks of Oxidants (EXPRESSO) and Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). BIBEX involved several campaigns, including: South Tropical Atlantic Regional Experiment (STARE), Fire Research Campaign Asia-North (FIRESCAN), FROSTFIRE, and the South East Asian Fire Experiment (SEAFIRE). STARE formed through combining the Transport and Atmospheric Chemistry near the Equator-Atlantic (TRACE-A) and Southern African Fire/ Atmosphere Research Initiative (SAFARI) activities. STARE was BIBEX’s first large campaign and concentrated on the biomass burnings in the regions of the Amazon basin, the tropical South Atlantic, and southern Africa. FIRESCAN was initiated in 1992 and addressed the role and atmospheric impacts of biomass burning in boreal ecosystems. FROSTFIRE acted in 1999 to investigate fire, climate, permafrost, and hydrology interactions. SEAFIRE held experiments in South-East Asia on the ecological impacts of biomass burning. BIBEX experiments gathered a decade of data that then contributed to the development of further studies on the impact of biomass burning on the atmosphere.

Biosphere-Atmosphere Trace Gas Exchange (BATREX), 1999 - 2003 or earlier

  • BATREX was created through the merging of four IGAC activities that all focused on trace gas emissions from terrestrial systems: BATGE, HESS, RICE, and TRAGEX.

Biosphere-Atmosphere Trace Gas Exchange in the Tropics: Influence of Land Use Change (BATGE), ~1995 - 1999

  • BATGE was an activity that provided research on nitrous oxide (N2O) and the compound effects of nitrogen sinks. It focused on trace gas emissions from terrestrial systems. BATGE helped to gain understanding of what factors control these fluxes and assessed the effects of land use change. BATGE was part of IGAC’s Phase I Tropical Atmospheric Chemistry focus and later merged into IGAC’s Biosphere-Atmosphere Trace Gas Exchange (BATREX) activity.

Bounding the Role of Black Carbon in Climate, 2009 - 2013

  • Bounding the Role of Black Carbon in Climate was a focused effort to produce an assessment report that summarized the most current knowledge on black carbon (BC) and its role in climate as well as provide a best estimate and uncertainty range for the radiative forcing by BC. The report was published in the Journal of Geophysical Research. This effort resulted from a request for such an assessment by national and international groups trying to formulate policies to mitigate short-term climate warming. It constituted a direct input to the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5), and was structured to accommodate the IPCC framework.

Direct Aerosol Radiative Forcing (DARF), 1996 - 2003 or earlier

  • DARF was initiated to determine the magnitude, uncertainty, chemical sources, and temporal and spatial variations of the direct radiative climate forcing by aerosols of various types, through observation as opposed to model output.

East Asia-North Pacific Regional Experiment (APARE), 1991 - 1996 or later

  • APARE aimed to understand processes controlling atmospheric chemistry in the rapidly developing East Asia region and the effects of airborne pollutants (ozone in particular) on downwind marine regions. APARE lead to a publication in a Terrestrial, Atmospheric and Oceanic Sciences in September 1995. More information regarding APARE and project results can be found here.

Emission of Methane from Wetland Rice Fields (RICE), 1994 - 1999

  • 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.

First Aerosol Characterization Experiment (ACE-1), 1995

  • 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. ACE-1 provided a background to be able to compare and quantify any anthropogenic perturbation and study progressively more complex environments.

Focus on Atmospheric Aerosols (FAA), 1995 - 2003 or earlier

  • 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.

Global Atmospheric Chemistry Survey (GLOCHEM), ~1992 -1996 or later

  • 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. GLOCHEM was also responsible for Measurements of Ozone in Airbus In-Service Aircraft (MOZAIC), which measured ozone and water vapor in the mid and upper troposphere by automated instrumentation aboard five commercial aircrafts.

Global HO Systematic Tests (GHOST), began 2003

  • 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.

Global Integration and Modeling (GIM), 1997 - 2003 or earlier

  • 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.

Global Tropospheric Ozone Network (GLONET), 1996 - 2003 or earlier

  • 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). This experiment assessed the performance of the different types of ozone sondes used in GLONET and within the World Meteorological Organizations (WMO) Global Atmosphere Watch (GAW).

High-Latitude Ecosystems as Sources and Sinks of Trace Gases (HESS), 1994 or earlier - 1999

  • 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.

Intercontinental Transport and Chemical Transformation (ITCT), 2001 - 2011

  • 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.

Marine Aerosol and Gas Exchange (MAGE), ~1995 - 2003 or earlier

  • The objective of MAGE was to study air-sea exchange and the formation and transformation of marine aerosols in part by making Lagrangian observations. MAGE organized the chemical experiment of The Atlantic Stratocumulus Transition Experiment (ASTEX), which took place in June 1992 in the stratocumulus-capped marine boundary layer. The purpose was to study the factors influencing the formation and dissipation of marine clouds. MAGE also organized an intercomparison experiment, ASGAMAGE, which had two phases, the first in May and the second in October of 1996. The primary objectives were to test new methods for measuring air-sea fluxes of CO2, N2O, CH4, and DMS and to compare these methods with established methods for estimating the transfer velocities of trace gases over the sea. MAGE and its experiments were essential for both properly describing the physics and chemistry of individual processes in models and for seeing whether models accurately predict nature’s response to anthropogenic emissions. The research findings of MAGE lead to publications in the Journal of Geophysical Research – Atmospheres February 1996 issue and in the Journal of Atmospheric Sciences August 1995 issue. More information and publications can be found here.

Megacities Asia, 2003 - 2012

  • The Mega-cities: Asia Task Team facilitated better coordination between groups making measurements of aerosols and oxidants in and around large cities in Asia. Their activities included maintaining a centralized web page; holding periodic workshops to increase communication between research groups; organizing instrument intercomparisons; and facilitating collaborative publications. The large-scaled, coordinated measurements of aerosols and oxidants in megacities in Asia provided the necessary observations to make the link between source emissions and regional-scale air quality and climate impacts. The results of Megacity Asia are summarized in the Asia chapter of IGAC/WMO report on The Impacts of Megacities on Air Pollution and Climate.

North Atlantic Regional Aerosol Characterization Experiment (ACE-2), 1997

  • ACE-2, part of the larger ITCT initiative, was the third major experiment, following ACE-1 and TARFOX that addressed the properties and effects of atmospheric aerosol relevant to radiative forcing and climate. Its goals were to determine and understand the properties and controlling factors of aerosol in the anthropogenically modified atmosphere of the North Atlantic and assess the relevance of aerosols on radiative forcing. The experiment performed several closure experiments and used the Lagrangian observational framework that was developed in ASTEX/MAGE and ACE-1. It took place from 16 June to 25 July 1997.

North Atlantic Regional Experiment (NARE), 1991 - 2001

  • NARE was an experiment that was implemented from 1991-1994 that was created through the merging of Atmosphere/Ocean Chemistry Experiment (AEROCE), which became a critical component of the project. It was established to study the chemical processes of the marine troposphere most impacted by industrial emissions. The primary objective was to investigate the chemical and transport processes that shape ozone distribution over the North Atlantic and to estimate the impact of human-induced emissions from North America and Europe on the production of tropospheric ozone and related parameters. NARE later merged with East Asian/North Pacific Regional Experiment (APARE) in the creation of Intercontinental Transport and Chemical Transformation (ITCT), which provided a broader geographical range perspective to chemical and transport processes.

Polar Atmospheric and Snow Chemistry (PASC), ~1990 - 1998 or later

  • PASC began in the early 1990s working towards coordinating polar tropospheric and snow/ice chemistry research. PASC helped identify knowledge gaps in polar atmosphere and snow chemistry along with aiding in understanding the role of tropospheric chemistry of Polar Regions in global change. PASC used atmospheric measurements and ice core records to analyze the human-induced changes of the polar atmospheric environment. A key research development was the measurement of the atmospheric composition of the middle to upper troposphere at the Summit in the Northern Hemisphere. PASC focused on the origin, transport and transformations of gaseous and particulate compounds in the high latitude troposphere. It also produced a better understanding of the atmosphere-snow interface complexities. PASC was also involved in the research discovery of tropospheric O3 loss during polar sunrise due to chemically reactive marine halogens released into the atmosphere found during the Polar Sunrise Experiment 1992 (PSE-92).

Stratosphere and Upper-Tropospheric Aerosols (SUTA), 1996 - 2003 or earlier

  • Advanced research on the dispersal and decay mechanisms for stratospheric aerosols. SUTA sought to find out if stratospheric aerosols serve as nuclei for cloud formation in the upper troposphere and stratosphere and if there is “background” stratospheric aerosol, what the source is. SUTA sought to find out if volcanic emissions on the stratosphere are adequately characterized in current models. SUTA also sought to find out if stratospheric aerosols are frozen or if they exist as supercooled liquid particles at low temperatures.

Trace Gas Exchange: Mid-Latitude Terrestrial Ecosystems and the atmosphere (TRAGEX), 1992 - 1999

  • TRAGEX sought to improve the understanding of increased concentrations and fluxes between the soil and atmosphere of trace gasses such as CO2,, CH4, N2O impacts on climate and precipitation. TRAGEX studied the factors controlling the fluxes and improved the ability to predict future fluxes. The project greatly improved understanding of the fluxes of these gasses in areas such as Russia, China and temperate South America, which were largely unknown prior to TRAGEX.

Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX), 1996

  • TARFOX was an IGAC activity that operated from 10-31 July 1996 and was established to provide information about the direct effects of tropospheric aerosols on the eastern seaboard of the United States. The principal goals were to:
      Measure the direct effects of tropospheric aerosols on regional radiation budgets of the cloud-free atmosphere, while simultaneously measuring the chemical, physical, and optical properties of the responsible aerosols
      Perform a radiative “column closure” study, using the degree of consistency and analyses of aerosol properties and effects to assess and reduce uncertainties in predicted aerosol climate effects
      Guide planning for future aerosol studies, such as ACE-2
      Extend measurements and analyses to other periods and regions with similar aerosol properties, using validated satellite remote sensing methods

    The activity included a combined ground, air, and space data collection to gather a wide variety of closure analyses. The early results from the activity indicated an unexpected importance of carbonaceous compounds and water condensed on aerosols in the East Coast haze plume. TARFOX was used to gather information on the composition and physical properties of aerosols in vertical columns in the lower troposphere. Data concluded that about 50% of the total aerosol mass was contributed by carbonaceous materials (sulfate was the only significant inorganic constituent of the aerosol). Also, it was found that the carbonaceous mass fraction was a function of the altitude, increasing at higher altitudes due to its resilience from being removed from the atmosphere. TARFOX demonstrated that carbonaceous materials in the atmosphere need to be given more examination. The results and data sets have been used to apply to the analyses of the absorption of solar radiation by black carbon (BC). Various articles have been published as a result of the data collected during the TARFOX activity, including publications in Journal of the Atmospheric Sciences and the Journal of Geophysical Research. More information about TARFOX and publications can be found here.

WMO/IGAC Impacts of Megacities on Air Pollution and Climate, 2008 - 2013

  • As of 2008, for the first time, the majority of the world’s population was living in urban areas, many in megacities (with populations over 10 million). Megacities are not only the center of growing economies, but are also large sources of air pollutants and climate-forcing agents. Under this initiative an assessment was written that for the first time summarized the current knowledge around atmospheric chemistry in megacities in Africa, Asia, South America, North America, and Europe. The assessment also summarized past and current research projects on this topic such as MEGAPOLI, CityZen, ICARTT, CalNex, MILAGRO, CareBeijing, PRIDE-PRD, and IMPACT. Finally the report identified knowledge gaps on atmospheric chemistry in megacities. The assessment was jointly sponsored by WMO.