Researchers at the USGS, the University of Michigan, the University of Arizona, and University of Technology, Sydney, Australia, are collaborating with scientists at Brazil's National Institute for Space Research and Federal University of Amazonas on a 3-year research project that investigates a basic yet unanswered question in Earth-system and global carbon-cycle science: What controls the response of photosynthesis in Amazon tropical forests to seasonal variations in climate?
Results of the study will help improve the reliability of global climate forecasts by guiding improvements in the treatment of tropical forest photosynthesis and related water-cycle processes in Earth-system models.
The project is designed to resolve disagreements between the computer models and actual forest measurements by developing new knowledge and deeper understanding of seasonal climate, photosynthesis, and water relationships in Amazon tropical forests through the use of advanced remote sensing techniques and field observations. The project focuses on existing tropical forest study sites near Manaus and Santarem, Brazil. Scientists will measure physiological properties of leaves and trees, and water flow, and use custom-designed remote sensing instruments with advanced capabilities for high dynamic range imaging to monitor the light-reflecting properties of the forest and the effects of clouds and smoke on solar radiation. Scientists will also model the three-dimensional variation in photosynthesis in various forest structures and light levels.
The project is supported by the U.S. Department of Energy, Office of Biological and Environmental Research, Climate and Environmental Sciences Division, and the GOAmazon campaign, in cooperation with the USGS Land Change Science Program.
The USGS High Dynamic Range All-Sky Imaging System (HDR-ASIS) measures the sky distribution of solar radiation at a study site near Santarem, Brazil. Data from this and other tower-based remote sensing instruments are helping USGS scientists and their collaborators develop improved capabilities to account for the role of tropical forests in the global climate system