Cascade Project at North Temperate Lakes LTER Core Data Physical and Chemical Limnology 1984 - 2016

Physical and chemical variables are measured at one central station near the deepest point of each lake. In most cases these measurements are made in the morning (0800 to 0900). Vertical profiles are taken at varied depth intervals. Chemical measurements are sometimes made in a pooled mixed layer sample (PML); sometimes in the epilimnion, metalimnion, and hypolimnion; and sometimes in vertical profiles. In the latter case, depths for sampling usually correspond to the surface plus depths of 50percent, 25percent, 10percent, 5percent and 1percent of surface irradiance.

理化变量监测工作于各湖泊最深处附近的中心观测站开展。多数情况下，监测于每日上午8时至9时进行。采样采用可变深度间隔的垂直剖面方式。化学指标监测的采样对象有时为混合层混合水样（PML），有时为表水层、斜温层及下层滞水层水样，有时则采用垂直剖面采样。当采用垂直剖面采样时，采样深度通常对应水面以下，分别达到表层辐照度50%、25%、10%、5%及1%的水深位置。