COMPOSITE STUDY ON INNER MONGOLIA SEMI-ARID GRASSLAND SOIL-VEGETATION-ATMOSPHERE INTERACTION(IMGRASS)

In order to deeply understand the climate\|ecology interaction, its processes and mechanisms, and its response and contribution to the global change of mid\|latitude (temperate) semi\|arid grassland, a major project called "Inner Mongolia Semi\|Arid Grassland Soil\|Vegetation\|Atmosphere Interaction (IMGRASS)" has been approved by NSFC and implemented during 1997-2001. IMGRASS is aimed at through mesoscale coordinated field observation, long term monitoring, analysis as well as numerical simulation to reveal multiple spatial and temporal scale and physical\|chemical\|biological processes, including the influence of human activities. Mesoscale field observation was conducted in 1998 growing season in Xilingol typical steppe of Inner Mongolia, which included observations of soil, vegetation, atmosphere parameters, various fluxes at land surface\|atmosphere boundary (sensible and latent heat, radiation, greenhouse gases), and precipitation. In this paper, the scientific objectives, background of experimental area, and field experiment implementation are introduced. Examples and preliminary analysis of some observations, such as atmospheric boundary layer profiles, soil moisture, radiation, surface reflectance, remote sensing related surface reflectance, AVHRR\|derived regional NDVI and LAI, as well as IMGRASS data\|base are also introduced. Numerical simulation and composite study of climate\|ecology interaction and human activity influence of IMGRASS project are described in an accompany paper in this issue.