Optical SWIR imaging spectroscopy of atmospheric methane (CH4) from space with TROPOMI/Sentinel-5P: Spatiotemporal trends and climatic drivers

This study utilized shortwave infrared (SWIR) observations from TROPOMI/Sentinel-5P (1.6–2.3 µm) to investigate atmospheric methane (XCH₄) variability across Bangladesh from 2018 to 2025. Persistent methane hotspots were detected over urban–industrial and rice-growing regions, with national XCH₄ increasing by about 10 ppb yr⁻¹ and localized trends reaching 45 ppb yr⁻¹. Strong seasonality was observed, with minima in spring and maxima in autumn, associated with industrial activity, wetland emissions, and post-monsoon hydrology. Pearson and Spearman analyses revealed a predominantly negative correlation of XCH₄ with temperature (−0.21/+0.06), along with positive correlations with pressure (+0.45/+0.20) and wind speed (+0.35/+0.34), and negative correlations with solar radiation (−0.34/−0.30) and precipitation (−0.27/−0.23). Machine learning (ML) and geographically weighted regression (GWR) models consistently identified temperature, wind speed, and pressure as dominant predictors. These results demonstrate the capability of SWIR spectroscopy for assessing greenhouse gas variability and climatic influences in tropical regions.