Assessment of methane levels throughout a temperate reservoir area using remote sensing data

Abstract

Aquatic ecosystems are significant methane (CH4) emitters, potentially surpassing direct anthropogenic sources. Despite the advantages of satellite monitoring, its application for assessing methane content over freshwater bodies is not commonly encountered in scientific publications. Therefore, this study aims to assess methane levels in the atmosphere in and around the temperate reservoir area (Kuibyshev Reservoir, Russia) using Sentinel-5P/TROPOMI remote sensing data. The spatial distribution of CH4 content across the study area was heterogeneous and exhibited a latitudinal dependence, with concentrations decreasing from south to north. Seasonal variability in methane levels is observed, with the lowest values in spring and the highest in autumn. The average CH4 concentration over the period 2019–2023 was 1860±13 ppb. Additionally, a consistent trend of increasing annual methane background levels has been observed (up to 1878±11 ppb in 2023). Differences in methane levels are noted across different land cover types, with higher values typically observed above anthropogenically transformed landscapes, while minimal ones are found over extensive forested areas and the waters of the Kuibyshev Reservoir.