North Temperate Lakes LTER: Light Extinction 1981 - current

A light (PAR) extinction coefficient is calculated for the water column for the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra, and Fish) and two additional lakes near Madison, Wisconsin (Waubesa and Kegonsa). Data exists only for the Trout Lake-area lakes through 2018. Beginning in 2019, the Madison-area lakes were added. The fraction of surface light is computed at 0.25-m to 1-m depth intervals depending on the lake. The light (PAR) extinction coefficient is calculated by regressing ln(fraction of light(z)) on depth z. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season Number of sites: 13

本研究针对11处主要湖泊（阿勒夸什湖、大北美狗鱼湖、水晶湖、斯帕克林湖、特劳特湖，以及未命名湖泊27-02[水晶沼]与12-15[特劳特沼]、门多塔湖、莫诺纳湖、温格拉湖、菲什湖），以及威斯康星州麦迪逊市周边的另外两座湖泊（沃贝萨湖、凯贡萨湖）的水柱，计算了其光合有效辐射（Photosynthetically Active Radiation，PAR）消光系数。截至2018年，仅特劳特湖周边的湖泊拥有相关观测数据；自2019年起，新增麦迪逊周边湖泊的观测序列。根据各湖泊的具体情况，在0.25米至1米的深度间隔内计算表层光照占比。光合有效辐射消光系数通过对深度z处的光照占比的自然对数与深度z进行回归分析计算得到。采样频率：无冰期为每两周一次，冰封期为每6周一次。采样点位总数：13处。