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Relationship of MISR RPV parameters and MODIS BRDF shape indicators to surface vegetation patterns in an Australian tropical savanna

Michael J Hill, University of North Dakota, hillmj@aero.und.edu (Presenting)
Clare Averill, NASA JPL, clare.storage@gmail.com
Ziti Jiao, Boston University, jiaozt@bnu.edu.cn
Crystal B Schaaf, Boston University, schaaf@bu.edu
John D Armston, Queensland Department of Natural Resources and Water, john.armston@iinet.net.au

The global coverage of bi-directional reflectance distribution function (BRDF) products from the Multi-angle Imaging Spectroradiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) could provide quantitative information on surface vegetation structure for input to process modelling and model-data assimilation schemes for regional and biome scale assessment of carbon dynamics. We examined the relationship of MISR RPV (Rahman-Pinty-Verstraete) model parameters, derived from inversion of MISR 275 m fine mode data, and BRDF shape indicators calculated from the latest MODIS 500 m MCD43 bidirectional reflectance distribution function (BRDF) product to vegetation patterns in an Australian tropical savanna, for a time series covering the dry season period from April to October 2005. The bi-directional reflectance products were compared with a GIS data coverage combining floristic polygons with Landsat TM-based estimates of canopy cover and height classes. The analysis showed that both the RPV theta parameter and MODIS BRDF shape indicators constructed using the red band were sensitive to local scale anisotropic scattering. The limited time series (8 dates), significant “no data” areas in many scenes, and strong influence of smoke haze on parameter values resulted in high standard deviations for the RPV theta parameter, and more confusion in signals between vegetation types. The NDHD-R, ANIF-R and other red-band shape indicators from MODIS produced distinctly different temporal profiles for major vegetation types such as rainforest, Melaleuca woodland, and Dichanthium grassland. These indices also showed evidence of consistent discrimination between Eucalypt savanna types which varied in canopy cover and tree height. A clumping index calculated from NDHD-R for day 177 showed good correspondence with savanna vegetation canopy properties, but was insensitive to dense canopy rainforest vegetation. These results indicate there is potential for both MISR and MODIS BRDF products to provide quantitative description of vegetation types in global tree-grass systems. However, there is a pressing need for further study to calibrate responses with fine scale structural data derived from both field measurement and LiDAR.


NASA Carbon Cycle & Ecosystems Active Awards Represented by this Poster:

  • Award: NNG05GG13G
    Start Date: 2005-02-15
     
  • Award: In progress
     

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