International MODIS/AIRS Processing Package

 MODIS Direct Broadcast (DB) Bidirectional Reflectance Distribution Function (BRDF) v1.0 release                  21 June 2010

   First release of a software package that takes MODIS direct broadcast geolocation (MOD03 or a1/t1*geo.hdf files) and surface reflectance (MOD09_L2/MYD09_L2) HDF files as input and creates BRDF/Albedo output tiled HDF files at 500 m and 1 km resolution. This process takes place in two phases:

  • Phase I: L2G Lite Surface Reflectance - generates land surface reflectances from MODIS Terra and Aqua data re-gridded to the MODIS Land Sinusoidal Tile Grid.   The MOD09_L2 Level 2 product that is required as input can be created as part of the IMAPP MODIS Virtual Appliance or through a stand alone MOD09 package.
  • Phase II: BRDF/Albedo - models tiles of daily BRDF and Albedo from 16 days of land surface reflectance tiles.
Both source and binary software are included. This release has been tested on both 32 and 64 bit Linux platforms and the statically linked 32 bit binary executables should work with most flavors of linux. There are also "Make" files that can be used to compile the software locally.

This release requires 1GB of memory for execution. Total disk usage will depend upon how many tiles and how many days are processed. Each pair (Aqua and Terra) of daily L2G surface reflectance Phase I product tiles (500m and 250m resolution) occupy approximately 0.5GB of disk space. Typically, 16 days of these will be retained for daily BRDF (Phase II) compositing. The 16-day composite BRDF tile files occupy approximately 150MB per tile.

Required Disk Space:

  • Daily L2G files = 1 GB/tile
  • 16 Day total = 16 GB/tile
  • BRDF/Albedo files = 150 MB/tile
  • Plus 5 GB Run Directory per day

Processing is executed through a single perl script which reads in the date/time window requested (default is to process the last 16 days) and the tiles to be processed (default is to process all tiles covered by the data) and begins execution of the L2G (Phase I) processing for each tile. Once that has completed, the BRDF/Albedo (Phase II) software is executed. The software takes about 1 hour per tile to complete, on a CentOS Intel Xeon 2.66 GHz CPU single processor with 2 GB of Memory. The majority of the time is spent on the 16 day BRDF compositing (40 minutes per tile), with the Phase 1 processing taking 3-4 minutes per tile.

The main perl script will use the HDFLook utility if it is found on your machine, to create quick look true color images from the output 1km BRDF tile files, as well as a composite image of all of the tiles processed. HDFLook is a free visualization tool that can be downloaded from: http://www-loa.univ-lille1.fr/Hdflook/

The DB BRDF software was provided by Dr. Crystal Schaaf and Dr. Yanmin Shuai of Boston University.

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