Rotation of the forest is defined as the number of forest disturbance events for the year range, with disturbance defined as a drop of Tree Canopy Cover from >=10% to 0%, or the loss from 1 to 0.

The pseudo-code for the rotation map can be written as:

sumloss = 0;
for (i = 0; i  0 or (tcc[i][y][x] == 0 and ((i > 0 and tcc[i-1][y][x] >= 10) or (i>1 and tcc[i-2][y][x] >=10 and tcc[i-1][y][x] > 0) or (i > 2 and tcc[i-3][y][x] >= 10 and tcc[i-2][y][x] > 0 and tcc[i-1][y][x] > 0)))){
        sumloss++;
    }
}
out[2][y][x] = sumloss;

We travel time for 3 years and see if there is a drop of TCC from >=10% to 0% within that time period. For example, the TCC datasets can be any of the following kind.

  1. TCC datasets as [11, 23, 40, 0, 11, 24, 68]
  2. TCC datasets as [11, 23, 11, 9, 0, 24, 55]
  3. TCC datasets as [11, 23, 11, 9, 7, 0, 24, 55]

These can be tweaked according to the country definition, and more conditions can be added as needed.

The source code for the same in Earth Engine can be found here.

Happy Earth Science 🙂