Lakes are key ecosystems within the global biogeosphere. However, the environmental controls on the biological productivity of lakes – including surface temperature, ice phenology, nutrient loads, and mixing regime – are increasingly altered by climate warming and land-use changes. To better characterize global trends in lake productivity, we assembled a dataset on chlorophyll-a concentrations as well as associated water quality parameters and surface solar radiation for temperate and cold-temperate lakes experiencing seasonal ice cover. We developed a method to identify periods of rapid net increase of in situ chlorophyll-a concentrations from time series data and applied it to data collected between 1964 and 2019 across 343 lakes located north of 40^∘. The data show that the spring chlorophyll-a increase periods have been occurring earlier in the year, potentially extending the growing season and increasing the annual productivity of northern lakes. The dataset on chlorophyll-a increase rates and timing can be used to analyze trends and patterns in lake productivity across the northern hemisphere or at smaller, regional scales. We illustrate some trends extracted from the dataset and encourage other researchers to use the open dataset for their own research questions. The PCI dataset and additional data files can be openly accessed at the Federated Research Data Repository at https://doi.org/10.20383/102.0488 (Adams et al., 2021).

中文翻译：

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全球温带和冷温带湖泊叶绿素-a 增加的速率和时间以及相关的环境变量

湖泊是全球生物地质圈内的重要生态系统。然而，对湖泊生物生产力的环境控制——包括表面温度、冰物候、养分负荷和混合机制——正日益因气候变暖和土地利用变化而改变。为了更好地描述湖泊生产力的全球趋势，我们组装了一个关于叶绿素-a浓度以及相关水质参数和经历季节性冰盖的温带和寒温带湖泊地表太阳辐射的数据集。我们开发了一种方法，可以从时间序列数据中识别原位叶绿素a浓度净快速增加的时期，并将其应用于 1964 年至 2019 年间收集的 40 ^∘以北 343 个湖泊的数据. 数据显示，春季叶绿素增加期出现得较早，可能会延长生长季节并提高北部湖泊的年生产力。叶绿素的数据集 -增加速率和时间可用于分析北半球或较小区域尺度的湖泊生产力趋势和模式。我们说明了从数据集中提取的一些趋势，并鼓励其他研究人员使用开放数据集来解决他们自己的研究问题。PCI 数据集和其他数据文件可以在联合研究数据存储库中公开访问，网址为 https://doi.org/10.20383/102.0488（Adams 等人，2021 年）。