Global equal area blocks in Geographic coordinates (Lat/Long) 

from Tyukavina et al. (in review) "Practical global sampling methods for estimating area and map accuracy of land cover and change classes"

Block properties:
	* The blocks have a static number of pixels in the North-South dimension for all latitudes, but an increasing number of pixels in the East-West dimension closer to the poles to maintain equal block area.
	* Block boundaries are aligned with the GLAD ARD 0.00025°x0.00025° https://glad.umd.edu/ard/home
	* Four block sizes: 2.5x2.5km (~6.25 km² area), 5x5km (~25 km²), 10x10km (~100 km²) and 20x20km (~400 km²).
	* Boundaries of blocks of these four sizes are aligned and nested in the North-South dimension, but area not aligned in the East-West dimension due to the changing lengths of the parallels.
	* Only blocks within land mass are provided, as defined by GADM version 2.0.

Each block has an individual ID from 1 to N to facilitate global sampling:
	2.5 km blocks: IDs from 1 to 23,895,602
	5km blocks: IDs from 1 to 6,024,755
	10km blocks: IDs from 1 to 1,528,374
	20km blocks: IDs from 1 to 391,847

Formats:
	* shapefile format (column "land_id" corresponds to unique ID 1-N). 
		5km blocks are separated into 2 shapefiles, for Northern and Southern hemispheres, and 
		2.5 blocks are separated into 4 shapefiles (NE, NW, SE, SW) to fit into a SHP format's 2GB size limit.
	
	* rasterized 10x10 degree tiles in GeoTiff format (raster value corresponds to "land_id" from the shapefiles)

	
If you have any questions about these blocks or have issues accessing the data, please contact Alexandra Tyukavina atyukav@umd.edu/ard/home