Crop fractions and pasture fractions
Each file contains 0.5 x 0.5 degree data.
Each year is in the format 720 columns by 360 rows,
where the top left corner corresponds to 180 degrees west,
90 degrees north.
In total there are 91 years,
(1900 at the start, 1990 at the end).
var is set to 0. over the ocean
read as an array :
real var(720,360,91)
open(10,file='crop_half.asc')
read(10,*)var