Unveiling Spatio-Temporal Patterns of Water Temperature in Lake Balaton Through Remote Sensing Data Analysis

Climate change is an inevitable phenomenon that has a great impact on the physical, chemical, and biological effects on water bodies, among which water temperature is a key parameter that needs to be closely monitored. As the largest lake in Central Europe, Lake Balaton provides important recreational and ecological values that could be affected by global warming and anthropogenic activities, which lacks comprehensive spatiotemporal analysis. Our study leverages multisource data on Google Earth Engine (GEE) to conduct a temperature variation analysis over two decades and detailed spatial variations across different parts of the lake, with in-situ data serving as both auxiliary and validation source. With an accuracy of 1.6 °C and a seasonal quantile difference within 1 °C, the satellite-based observations are in good agreement with the in-situ measurements. In the inter-annual analysis, water temperature increases at 0.7 ℃/decade, closely paralleling the 0.6 ℃/decade rise in air temperature, with more notable warming in annual minimum and winter temperatures, particularly in the shallowest basin. For intra-annual temperature analysis, we propose a cumulative temperature anomaly method to examine temperature variations in each month, which shows distinct change patterns between different basins. This implies that during warmer months, the western, shallower regions exhibit relatively higher temperatures, while in cooler months, the deeper, eastern areas show elevated temperatures. Water depth has high correlations with seasonal temperature of the entire lake. In near-coast areas, windspeed induces cooling effects, while artificial surfaces contribute to water warming. The GEE user interface provides easy access for scientists and the public, and the open-source code can be readily customized to other lakes.