Roles of Long-Term Flux Observations as the Global Change Study and the Current Topics

Abstract

Continuous long term micrometeorological CO2 flux observation has become an essential component to accurate determine CO2 uptake in terrestrial ecosystems after COP3. Because the intergovernmental agreement on CO2 emission control (Kyoto protocol) allows each country to subtract the annual accumulation of CO2 uptake by their ecosystems from the total anthropogenic CO2 emission. Hence, the demands to determine the CO2 uptake more accurately at the ecosystem level, and to make the long term CO2 flux observation a major research within multidisciplinary study fields such as ecology, biology, meteorology and agriculture have been increased significantly. Several flux observation sites have been operating in ecosystems of North America and Europe since 90's. These sites were initially independent research projects, but were later organized into networks such as AmeriFlux and EUROFLUX. FLUXNET was also established to enhance the understanding of ecosystem CO2 exchange including data exchange and to promote the measurement methodology among the networks. AsiaFlux was established in fall of 1999 as part of a flux observation research network in Japan and some Asian countries. The Study Group for Flux Measurement and Evaluation (S-FluME), the Society of Agricultural Meteorology of Japan (SAMJ) was organized to enhance the research activities of flux observations, and has been contributing to the activities of AsiaFlux. This paper reviews the development of theoretical and practical methodology of flux observation and discusses topics that arose from previous long term flux observations. Some suggestions and comments to improve the flux determination are also shown. © 2003, The Society of Agricultural Meteorology of Japan. All rights reserved.