Evaporation : two u . s . weather bureau class a pans are operated at king s park . the mean water temperature is taken to be the mean of the daily maximum and minimum surface water temperature 蒸发:天文台使用两个美国气象局甲级蒸发皿于京士柏气象站量度蒸发量,以皿内每日量得的最高及最低水面温度之平均数作为当日的平均水温。