Austral Winter and Spring in Queensland's Brigalow Belt
A newly-released data product from NASA's Multi-angle Imaging SpectroRadiometer (MISR) is currently being examined by the Queensland Department of Natural Resources and Mines (DNRM), Australia, with the intent of utilizing multiangle and multispectral information to assess the structural properties of vegetation and improve the mapping and monitoring of forest and woodland areas. The new product consists of "Local Mode" high- resolution image data, which provide 275-meter spatial resolution georectified imagery in all 36 channels (nine cameras x four spectral bands) of the instrument, for selected target areas. This contrasts with the otherwise continual Global Mode data, which provides imagery at 1.1-kilometer resolution in 24 of the 36 channels, and 275-meter resolution in the other 12. Since the beginning of the Terra mission, Local Mode data have been routinely acquired for dozens of targets around the globe, and the software to generate georectified imagery systematically from these data has recently become operational at the NASA Langley Atmospheric Sciences Data Center, where MISR's standard data products are created.
Surface changes across the Southern Brigalow Belt in central Queensland are illustrated by these six image panels acquired by MISR on June 7 (left) and September 27 (right), 2003, during the austral winter and spring seasons, respectively. This is the region of study for the pilot phase of a project conducted by Queensland's Statewide Landcover and Trees Study (SLATS). SLATS is using MISR Local Mode data to assess the relationship between multiangular reflectance and structural properties of forests and woodlands across the state.
The top panels display data from the near-infrared, red and green spectral bands of MISR's vertical-viewing (nadir) camera as red, green and blue, respectively, causing highly vegetated areas to appear red. Above image center, the area of the densely vegetated Carnarvon Gorge National Park appears very bright at the near-infrared spectral band. In the lower left, the Warrego River flows southward through grassland areas toward the Murray-Darling river system. In several areas, particularly along the right-hand portion of the images, a reduction in photosynthetic activity for pastures and/or grasslands is indicated between the winter and spring dates due to a dry spring.
The central panels are multi-angular composites in which data from the near-infrared band of MISR's 60° forward, nadir, and 60° backward viewing cameras are displayed as red, green and blue, respectively. The bottom panels display red-band data in the same configuration from the same cameras. Within the composites, color variations serve as a proxy for changes in angular reflectance, which are in turn influenced by vegetation structure, terrain and soil type, and by the different solar illumination conditions on the two dates. In the near-infrared band composites the Carnarvon Gorge area appears almost uniformly bright because of high transmittance of the leaves at near-infrared wavelengths and relatively low angular variation. This area appears dark in the red multiangle composites due to high absorption at the red band from the relatively uniform, dense tree canopy. In other words, sunlight at near-infrared wavelenths is strongly scattered between the leaf layers of the dense canopies, and the influence of shadows between the tree crowns is less pronounced compared with open woodlands.
The Multiangle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82° north and 82° south latitude. These data products were generated from a portion of the imagery acquired during Terra orbits 18460 and 20091. The panels cover an area of 256 kilometers x 247 kilometers, and utilize data from blocks 110 to 112 within World Reference System-2 path 93.
MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.
Credit: Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
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Text acknowledgment: Clare Averill (Raytheon / Jet Propulsion Laboratory) and John Armston (SLATS Team, Department of Natural Resources and Mines, Queensland).