The files in this directory were produced by the ISLSCP2 staff based on the 30
arcsecond (~1km) Earth Observing System (EOS) Digital Elevation Model (DEM)
provided by Dr. Thomas Logan from NASA/Jet Propulsion Laboratory (JPL). These
are global, coarse resolution (1/4, 1/2 and 1 degree spatial resolutions) binary
( 1 and 0) overlays of land/water and land/sea boundaries.

The ISLSCP2 masks are based on the best available 30 arcsecond (~1km) land/water
masks produced at JPL in support of the EOS AM-1 satellite platform. The JPL
masks are based in turn on vector data from the World Vector Shoreline (WVS)
database (Solluri and Woodson 1990) for coastlines, and the Digital Chart of the
World (DCW) (Danko 1992) for inland water bodies. The WVS is based on older
1:250,000 scale Defense Mapping Agency JOG (Joint Operational Graphics) charts
produced from a variety of sources. DCW is based on a photogrammetric consistent
mapping at a scale of 1:1,000,000. The ISLSCP2 staff have aggregated the 1km
data to spatial resolutions of 1/4, 1/2 and 1 degree, in the process generating
layers with the percentage of land/water or land/sea cells within the coarse
resolution cells. An arbitrary threshold of greater than or equal to 50% water
was used to designate water dominated cells and to produce binary land/water or
land/sea masks for the data collection.