The East Asian continental rim region is characterized by anthropogenic emissions that are already high in many locales and that are rapidly growing throughout much of the region. For example, recent projections indicate that anthropogenic NO_X emissions from Asia, primarily from the combustion of hard coal and liquid fuels for power, transportation and industry will continue to rise for the foreseeable future. An increase in NO_X emissions of 350% from 1990 to 2020 is predicted if no further pollution controls are implemented [van Aardenne et al., 1999]. Furthermore, emissions from eastern Asia are increasing more rapidly than in most other parts of the world. Within two decades, emissions from eastern Asia could account for roughly half of the S and N and a third of the C emitted from all anthropogenic sources worldwide [Galloway et al., 1998]. The Asia/western Pacific region has a unique mixture of aerosols and trace gases because of these distinctive patterns of emissions in combination with the particular meteorological conditions affecting the region.

Aeolian dust and gaseous and particulate pollutants from the Asian continent are transported eastward over the Pacific, especially in the spring, and the effects of these materials are widespread [Berntsen et al., 1999; Jaffe et al., 1999]. For example, growing levels of nitrogen oxides from the expanding transportation sector in Asia will change the oxidizing capacity of the atmosphere beyond the regional scale [Elliot et al., 1997]. Similarly, recent modeling studies indicate that increasing emission from fossil fuel combustion in Asia will affect surface ozone concentrations in the United States [Jacob et al., 1999]. These authors suggest that the long-range transport of Asian O₃ could even offset some expected benefits of reduced emissions of NO_X and hydrocarbons in the western US.

Anthropogenic materials in the atmosphere can also influence climate by altering the Earth's radiative balance. Concerns over climate forcing have led to the development of the ACE-Asia experiment, which focuses on the Asia/Pacific region. ACE-Asia is the third in a series of Aerosol Characterization Experiments (ACE) planned under IGAC auspices. The TRACE-P (TRansport and Chemical Evolution over the Pacific) Program, part of NASA's Global Tropospheric Experiment, will focus on outflow from Asia with the goals of (1) understanding and quantifying the export of chemically and radiatively important gases and aerosols, and their precursors and (2) determining and understanding the evolution of these air masses. Continental outflow also affects biogeochemical cycles of the North Pacific [Duce et al., 1991], and the associated effects on marine biology and chemistry could also have climate implications.

Despite the recent interest and obvious urgent need for systematic studies of atmospheric chemistry and the impacts of natural and anthropogenic substances in this region, little research had been done on these topics until the early 1990s. The East Asian/North Pacific Regional Experiment (APARE) was established as an IGAC Activity in March 1990 largely to address this need. Thus, the APARE program has been concerned with the oxidizing capacity of the regional atmosphere, the tropospheric ozone budget, the deposition of acidic substances, and the effects of continental emissions on marine atmospheric chemistry and biogeochemistry. Marine activitities carried out in conjunction with APARE include cooperative endeavors with the Joint Global Ocean Flux Study (JGOFS), another IGBP Core Project. The following goals and tasks are the focus of APARE:

Goals

To assess transport and chemical transformations of air pollutants over the East Asian continent and the northwestern Pacific Ocean.

To determine the depositions of primary and secondary pollutants (sulfate, nitrate, organics) in the East Asian region.

Tasks

• Emission inventory and air chemistry database
• Surface measurements of important trace gases
• Intensive field programs
• Ground–surface monitoring network

Scientists from Australia, China, Japan, Korea, Taiwan and the United States took part in the first APARE planning meeting, which was held in Tsukuba, Japan.

Dr. Hajime Akimoto, then at the National Institute of Environmental Sciences, was elected as convener of APARE. Under his leadership, the APARE community has successfully undertaken several sub-programs, including the Pacific Exploratory Mission-Western Pacific (PEM-West), Perturbation of the East Asian Continental Air Mass to the Pacific Oceanic Troposphere (PEACAMPOT) and CATS (Chemistry of the Atmosphere, Taiwan Station), which were proposed and accepted as international projects by the APARE Coordinating Committee.

Review of APARE/IGAC Activities

• 1st Planning Workshop, March 1990, Tsukuba
• 2nd Planning Workshop, March 1991, Tsukuba
• 1st Intensive Field Campaign, PEM-West PEACAMPOT/CATS: Phase A, Sept.-Oct., 1991
• 3rd Planning Workshop, Nov. 1992, San Francisco
• International Conference on Regional Environment and Climate Change in East Asia, 1993
• 4th Steering Committee Meeting, Dec. 1993, Taipei
• 2nd Intensive Field Campaign, PEM-West/PEA- CAMPOT/CATS/H.K. Station: Phase B, Feb./March, 1994
• Regional Environmental Changes in East Asia, APARE/IGAC special issue of Terrestrial Atmospheric and Oceanic Sciences, Vol. 6, Number 3,
  Sept. 1995
• 5th Planning Workshop, January 1996, Tokyo
• PEM-West A Special issue, J. Geophys. Res., 101, D1, Jan. 1996
• 6th Planning Workshop, March 1997, Hong Kong
• PEM-West B Special issue, J. Geophys. Res., 102, D23, Dec. 1997
• 7th Planning Workshop/Tour, March 1998, Seoul/Cheju
• APARE/TRACE-P Planning Meeting, Oct. 1998, Hong Kong
• 8th Planning Workshop/Tour, June 1999, Honolulu/MLO

At the 8th Planning Workshop in 1999, the APARE Coordinating Committee endorsed both the TRACE-P campaign and the ACE-Asia experiment. Multi-platform field campaigns for both of these programs are planned for spring 2001 with particular emphasis on continental outflow, including studies of trace gas and aerosol composition and reactions, aerosol physical and optical properties, radiative effects of the aerosols, and chemical evolution. At present, scientists from China (including Hong Kong), Japan, Korea, and Taiwan are operating a network of ground surface monitoring sites in East Asia in conjunction with APARE. These sites will form the backbone of an ACE-Asia ground station network, providing data on aerosol chemical, physical and optical properties that will be used to assess the spatial and temporal (seasonal and inter-annual) variability of these properties and the factors controlling this variability.

The current members of the APARE Coordinating Committee are:

• M. Uematsu (Univ. of Tokyo, Japan, Convener)
• M. Anson* (Hong Kong Polytechnic University)
• R. Arimoto (New Mexico State University, USA)
• Y. Kondo (Nagoya University, Japan)
• C.M. Liu* (National Taiwan University)
• R. Newell (Mass. Inst. of Technology, USA)
• S.G. Shim (Korea Inst. Science & Technology)
• J. Tang (Chinese Meteorol. Admin., China)
• Y. H. Zhang (Peking University, China)

*will rotate to new members during 2000.

The APARE community is rather unique because it is a non-governmental organization composed of scientists who are doing atmospheric chemistry research in the Asia/Pacific Rim region. This Activity presents valuable opportunities for those interested in exchanging information concerning ongoing projects, for discussing the scientific results from their experiments, and for coordinating future projects with scientists from multiple countries through APARE workshops, especially those in the Asian countries. The APARE Coordinating Committee exists to communicate, create, and conduct atmospheric research with scientists interested in the East Asia region. At the most recent meeting, the Committee agreed to begin contacting scientists from other Asian countries to broaden the geographical coverage and possibly enlarge the scope of APARE. The 9th workshop will be held at Xi Ning, China in June 2000.

The following articles in this issue of IGACtivities summarize several recent scientific projects undertaken in cooperation with APARE.

References

1. Berntsen, T.K., S. Karlsdottir, and D.A. Jaffe, Influence of Asian emissions on the composition of air reaching the North Western United States, Geophys. Res. Lett., 26, 2171-2174, 1999.
2. Duce, R. A., et al., The atmospheric input of trace species to the world ocean, Global Biogeochem. Cycles, 5, 193-259, 1991.
3. Elliott, S., et al., Atmospheric effects of the emerging mainland Chinese transportation system at and beyond the regional scale, J. Atmos. Chem., 27, 31-70, 1997.
4. Galloway, J. N., D. S. Ojima, and J. M. Melillo, Asian change in the context of global change: An overview, in Asian Change in the Context of Global Change, edited by J. N. Galloway and J. M. Melillo, pp. 1-17, Cambridge Univ. Press, 1998.
5. Jacob, D.J., J.A. Logan, and P.P. Murti, Effect of rising Asian emissions on surface ozone in the United States, Geophys. Res. Lett., 26, 2175-2178, 1999.
6. Jaffe, D. et al., Transport of Asian air pollution to North America, Geophys. Res. Lett., 26, 711-714, 1999.
7. van Aardenne, J.A., G.R. Carmichael, H. Levy II, D. Streets, and L. Hordijk, Anthropogenic NOX emissions in Asia in the period 1990-2020, Atmos. Environ., 33, 633-646, 1999.