USGS 30-second global 24-category vegetation (land-use) map: 

       a) data file: veg30susgs.gz (Unit: integer, ranging
                     from 0 to 24. 0: missing point)
       b) resolution: 30-second
       c) program: read_usgs_veg.f
          To save the disk space, all input data are in character
          strings (either 1-character string (for land-use, land-water, vegetation
          fraction) or two-character string (for soil temperature)). The program
          provided here is used to transfer these characters into integer.
       d) Note: Data start at latitude 90 and longitude -180. The file is 
          in direct access format and each direct access record contains 
          data in one latitude circle beginning at -180 degree longitude, 
          and ending at +180 degree. The data are arranged to start at 
          northernmost latitude (north pole) and end at south pole     
       e) filling gaps: This data set is based on USGS 24-category landuse map Version 
          2 obtained from USGS/EROS center (http://edcdaac.usgs.gov/glcc/globe_int.html). 
          Gaps in the original data (particularly over Hawaiian islands)
          were filled with climatology estimates. For each 15-degree
          latitude circle starting from N 90 degree, the dominant landuse 
          categoty was selected as a climatology estimate.