Remote Sensing of Atmospheric Methane (XCH 4 ) Concentrations over Lake Ecosystems: Seasonal Dynamics and Environmental Drivers in Eğirdir and Burdur Lakes of Türkiye

As lakes contribute significant amounts of methane (CH 4 ) to the atmosphere, they account for a significant share of the global greenhouse gases (GHGs) budget. Since lakes are ecosystems where physical and biological processes influencing CH 4 formation are concentrated, the study focuses on atmospheric CH 4 column concentrations over lake areas. This study aims to analyze the temporal variation in atmospheric CH 4 column concentrations (XCH 4 ) over Lake Eğirdir and Lake Burdur in Türkiye in 2023 and 2025 as well as the relationship between XCH 4 and environmental parameters such as Water Surface Temperature (WST), Normalized Difference Chlorophyll Index (NDCI), and Floating Algae Index (FAI). The temporal variability of XCH 4 observed over both lakes showed statistically significant positive correlations with lake-area-averaged WST, NDCI, and FAI (Pearson r = 0.49–0.65, p < 0.01). This outcome indicates consistent temporal patterns between XCH 4 and environmental conditions at the lake scale. Furthermore, time-series graphs show that monthly average XCH 4 values in both lakes reached their highest levels during the summer and autumn months. During these periods, XCH 4 concentrations exceeded 1860 ppb in Lake Eğirdir and 1900 ppb in Lake Burdur. The areas of land use/land cover (LULC) classes surrounding the lakes were evaluated together with XCH 4 , and relatively higher XCH 4 values were observed over agricultural areas, which constitute the dominant class in the basins of both lakes. The distribution of XCH 4 throughout the lake depth showed higher values in the shallow and mid-depth zones and lower values in the deeper areas beyond 20 m, indicating that the distribution of XCH 4 varies throughout lake depth. The results obtained underline the importance of remote sensing data in monitoring XCH 4 in lake ecosystems.