ICOADS Web information page (Tuesday, 07-Jan-2014 23:58:02 UTC):

Figure 4

Figure 4. 1° landmask (lstags) developed by Dick Reynolds: black for land areas, red for ocean.

[Links to detailed][Landmask files]

U.S. National Oceanic and Atmospheric Administration hosts the icoads website privacy disclaimer
 Document maintained by icoads@noaa.gov
Updated: Jan 7, 2014 23:58:02 UTC
http://icoads.noaa.gov/mask_fig4.html