The Essential Climate Variable 'Lakes': exploring satellite-products from global to local scale

Lakes are integrators of environmental and climatic changes occurring within their contributing basins. Understanding the complex behavior of lakes in a changing environment is essential to effective water resource management and mitigation of climate change. The ESA CCI Lakes is a multi-disciplinary project (https://climate.esa.int/en/projects/lakes/) creating the largest and longest consistent global record of five lake climate variables: lake water level, extent, temperature, surface-leaving reflectance, and ice cover. Phase 1 covered 250 lakes and phase 2 will cover up to 2000 globally. The distribution of the global dataset will be presented followed by a focus on Lake Trasimeno, a shallow eutrophic lake in central Italy included in the Long-Term Ecosystem Research (LTER) network. We used AI and Non-Parametric Multiplicative Regression (NPMR) to analyze the data. Chlorophyll-a in lake Trasimeno was dominated by a summer bloom initiating in July and peaking in early September and was largely predicted by the time variable - accounting for 87% of feature importance. The North Atlantic Oscillation was the next most important variable (4% feature importance) corroborated by NPand shown to be largely important during early to mid-September when a positive NAO, associated with high pressure and warm sunny weather, led to an increase in chlorophyll-a concentrations. Regional climatic indices as well as the more obvious nutrient drivers of algal blooms should therefore be considered in lake management. High Frequency chlorophyll-a and phycocyanin data from a WISPstation showed that rapid fluctuations visible in the satellite record are supported by in situ data.