PARENT SESSION
Organized Oral Session 5: Biome and Coastal Models for Local Sites and Biosphere Regions
Organized by: JS Olson and D Ojima
Friday, August 8. 9:00 AM to 12:00 PM, SITCC Meeting Room 106.
Monitoring local and global vegetation productivity and surface resistance using Moderate Imaging Spectrometer (MODIS).
Kang, Sinkyu *,1, Kim, Joon2, Heinsch, Faith Ann1, Zhao, Maosheng1, Kimball, John1, Running, Steven1, 1 Numerical Terradynamic Simulation Group, School of Forestry, University of Montana, Missoula, MT, U.S.A.2 Department of Atmospheric Sciences, Yonsei University, Seoul, Rep. Korea
ABSTRACT- Moderate Imaging Spectrometer (MODIS) provides improved remote sensing technology for monitoring global vegetation phenology and productivity, and surface resistance at 1km nadir resolution every eight days. As well, these biophysical products can be used as inputs for global biosphere models to improve our understanding of global carbon and water processes. For this, MODIS biophysical products should be validated using ground measurements, which represent at least 1km2 area. Currently, fluxtower gives unique opportunity to provide ground truth data comparable with MODIS 1km biophysical products. For this purpose, we selected representative fluxtower sites each from evergreen needleleaf forest (ENF), evergreen broadleaf forest (EBF), deciduous broadleaf forest (DBF), savannah, and crop biomes, respectively. This study (1) demonstrates ability of MODIS to capture seasonal and spatial variability of GPP and surface resistance; (2) validates MODIS GPP and surface resistance at fluxtower sites across divers biomes; and (3) discusses practical considerations of the MODIS products for monitoring terrestrial carbon and water processes at local and global scales. We also evaluated the spatial patterns of the MODIS products using fine-scale optical remote sensing data (IKONOS and Landsat ETM+), incorporated with fluxtower measurements. At sites for which tower eddy-flux measurements are available, MODIS GPP follows the general trend, capturing onset of leaf growth, and in many cases, leaf senescence, while tending to over-estimate total tower GPP. The MODIS GPP algorithm effectively captures the effects of stress events, such as late-summer dry-down, on canopies.
Key words: productivity, eddy covariance, MODIS, surface resistance