The Lakes_cci project: presenting the satellite-derived lakes variables for climate studies

Lakes are a vital resource for freshwater supply, and key sentinels for global environmental change. They are responding rapidly to climate change and in coming decades it is projected that global warming will have a more persistent and stronger effects on hydrology, nutrient cycling, and biodiversity. Factors driving lake condition vary widely across space and time, and lakes, in turn, play an important role in local and global climate regulation, with positive and negative feedback depending on the catchment; the Global Climate Observing System actually defines "Lakes" as an Essential Climate Variable (ECV). Understanding the complex behaviour of lakes in a changing environment is essential to effective water resource management and mitigation of climate change effects and, in such a context, satellite systems offer globally consistent observations. This contribution aims to present the Lakes_cci project funded by the European Space Agency (ESA) that uses satellite data to create the largest and longest possible consistent, global record of the following lake climate variables: Lake Water Level (LWL), Lake Water Extent (LWE), Lake Surface Water Temperature (LSWT), Lake Ice Cover (LIC) and Lake Water-Leaving Reflectance (LWLR). The data span combined satellite observations from 1992 to 2020 inclusive and quantifies over 2000 relatively large lakes, which represent a small fraction of the number of lakes worldwide but a significant fraction of global freshwater surface. Selected uses cases will be presented to demonstrate the scientific contribution of the project; for instance in understating the response of phytoplankton in European lakes to the 2019 heatwave events, and in supporting a long-term lake ice phenology data record of the Northern Hemisphere. With this presentation we aim to discuss with the community the dataset exploitation by also sharing tools for data analysis and by promoting an user survey to support the research of lakes scientists.