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North Carolina MODIS Albedo Project

   In the summer of 2007 an independent research project was completed by Bruce Corliss with Dr. Rob Jackson at Duke University to examine the surface albedo variation of North Carolina from the NASA MODIS Aqua and Terra satellites.  Both temporal and spatial variations for albedo were examined with multiple forest cover types to see how albedo varied on a local scale. 


Homogenous Forest Site Selection

   A set of 21 sites that appeared to contain relatively homogenous forest cover were selected for analysis with Google Earth.  Several land cover data sets were used to validate these sites: 200m LANDSAT, 1 km AVHRR, 2001 NLCD, and the 1 km MODIS land cover product MOD12Q1 (included with the ORNL temporal albedo data for each site).  All of these sets, along with the coordinates of each site, were loaded into ArcGIS and the local homogeneity of forest cover was examined.  There was not much agreement between the data sets even though all of them have been scientifically verified to some degree, so it was decided to use the 1 km MODIS Land Cover Product since it used the most spectral bands for analysis and was the most recently published.


Albedo Data Processing

  The albedo variation at these sites were examined using the processed data from the ORNL DAAC website.  At each site, homogenous forest cover pixels were filtered using a MATLAB m-file (see downloads) and temporal blue-sky albedo data was extracted and examined. Unfortunately, only relatively small swaths of land could be examined with this method (maximum of 7 by 7 kilometer squares). Even though ORNL DAAC had the capability on their website to process albedo at custom dimensions and geographic coordinates, MATLAB could not correctly import data with any other dimensions. Composite graphs of homogenous pixels at each site were made and basic statistical information such as annual mean, median, range, range (95th percentile - 5th percentile) was examined. The data acquired from the analysis is found in Results, and there is also a Discussion of the significant of the trends found.