Spatial Datasets for NH₃-N Remote Sensing Analysis in the Guangdong–Hong Kong–Macao Greater Bay Area

Description This dataset contains spatial data prepared for a study of ammonia nitrogen (NH₃-N) concentrations in the Guangdong–Hong Kong–Macao Greater Bay Area from 2015 to 2025 using Sentinel-2 imagery and machine learning. The shared materials include the study-area boundary and water masks used for spatial analysis and visualization. These datasets support the definition of the study area, extraction of water pixels, and analysis of the spatial distribution of NH₃-N concentrations. Coordinate reference system information and descriptions of the included files are provided in the accompanying metadata. The original water quality observations from China's national automatic surface water quality monitoring stations are not included because the authors do not have authorization to redistribute these data. Other restricted materials are also excluded from this dataset.