Rates and timing of chlorophyll-a increases and related environmental variables in global temperate and cold-temperate lakes

The files in this repository were created using code that is available in the associated GitHub repository (https://github.com/hfadams/pci) and in Zenodo (https://doi.org/10.5281/zenodo.6972355), which was used to standardize and compile a dataset of in situ chlorophyll-a data and related water quality data and for lakes at or above 40° N across the Northern hemisphere. Original data files are not included in this repository but can be found by following the links in the data sources tables in the SHARING/ACCESS INFORMATION section in the README. The period of chlorophyll-a increase (PCI) dataset contains chlorophyll-a rate of increase along with mean water quality variables (i.e., surface water temperature, nutrients, and solar radiation (SSR)) during periods of rapid algal growth referred to as the PCI. PCI's were defined based on the normalized rate of change in the fluctuating chlorophyll-a concentration sampled over the year, and categorized as occurring in the spring, summer, or as a "single" PCI when there was one main period of growth. Additional lake parameters were included from the HydroLAKES and HydroATLAS databases, and trophic status index (TSI) was calculated from chlorophyll-a concentrations. This dataset is intended to be used to explore trends between changing environmental conditions and lake productivity. However, as a compiled dataset, the PCI data is based on lake samples collected from a variety of organizations with differing methods. Great care was taken to standardize the data and provide all relevant metadata wherever possible