lake_area_fraction 1 [XXXX] "Area fraction" is the fraction of a grid cell's horizontal area that has some characteristic of interest. It is evaluated as the area of interest divided by the grid cell area, or if the cell_methods restricts the evaluation to some portion of that grid cell (e.g. "where sea_ice"), then it is the area of interest divided by the area of the identified portion. It may be expressed as a fraction, a percentage, or any other dimensionless representation of a fraction.