Data Set "DSP04_GRIDDED_FT_MAPS"
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Revised: February 14, 2001


BOREAS Follow-on DSP-4 1994 ERS-1 Level-4 Landscape Freeze/Thaw Maps

The BOREAS DSP-4 team acquired and analyzed imaging radar data from the ESA's
ERS-1 over a complete annual cycle at the BOREAS sites in Canada in 1994 to
detect shifts in radar backscatter related to varying environmental conditions.
Two independent transitions correlating with snow melt and soil thaw onset, and
possible canopy thaw were revealed by the data. The results demonstrated that
radar provides an ability to observe thaw transitions at the beginning of the
growing season, which in turn helps constrain the length of the growing season.
The data presented here are gridded maps of landscape freeze/thaw state derived
from backscatter change maps. The backscatter change maps were computed from
radar backscatter images covering the southern BOREAS sites. The freeze/thaw
classifications were determined through application of a change detection
threshold based on temporal backscatter change relative to a winter-time frozen
reference state. The data are provided as both ASCII text and as binary image
(*.gif) format files.

Acknowledge: Kyle McDonald


File Inventory Information
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The data set consists of 33 pairs of data files, representing observations
from 33 days of 1994.  The DAT files (*.dat) provide ASCII tables for each
day, each with 66x60 lines in three columns of: 

  (1) percent frozen landscape (column 1)
  (2) percent thawed landscape (column 2)
  (3) percent open water area (column 3) 

for each grid cell region.  Missing data and are not indicated in the tables.
The grid begins in southwest corner and proceeds eastward first. 

The GIF files (*.gif) corresponding to each of the *.dat files are pictorial
repesentations of the data provided in the *.dat files.  Each bin is shown
in a combination of red, blue, green and black, where:

  red = area fraction of the grid cell that is thawed
  blue = area fraction of the grid cell that is frozen
  green = area fraction of the grid cell that is lake
  black = area fraction of the grid cell that has no data or is missing data