. . "Climate and Forecast (CF)" . "The surface called \"surface\" means the lower boundary of the atmosphere. \"change_over_time_in_X\" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. \"Amount\" means mass per unit area. Surface amount refers to the amount on the ground, excluding that on the plant or vegetation canopy." . "change over time in surface snow amount" . .