GLCD250-MOD: Global Lakes Chlorophyll-a Daily 250 m based on MODIS

GLCD250-MOD is a global dataset of chlorophyll-a (Chl-a) concentrations for inland lakes. It provides daily Chl-a estimates at 250 m spatial resolution over a 25-year period (2000–2024). Chl-a concentration is estimated by a trained transformer-based hierarchical deep learning model based on MODIS satellite observations. With its high-resolution Chl-a estimates, GLCD250-MOD improves data availability for small lakes compared to the MODIS Terra Level-3 product (4.6 km spatial resolution, daily). GLCD250-MOD covers 495,966 lakes selected from the HydroLAKES database. The dataset is expected to support enhanced analysis of algal bloom dynamics, enabling monitoring of spatiotemporal bloom patterns and detection of long-term global changes in inland lake ecosystems. GLCD250-MOD provides the variable 'chlor_a', representing chlorophyll-a (Chl-a) concentration. The dataset also includes geospatial information for each lake in 'Lake_info.zip', which contains a shapefile (.shp) describing lake attributes, including the HydroLAKES Hylak_id, lake name, continent, centroid coordinates, file location, and polygon geometry. The total dataset is distributed across multiple compressed files (.tar) categorized into three tiers based on lake size and data volume: Tier 1. Caspian Sea (Hylak_id: 1): Given its substantial data volume, the Caspian Sea is provided in a dedicated archive (0000001.tar) containing annual split files (e.g., GLCD250-MOD_0000001_2000.nc). Tier 2. Major Lakes (Hylak_id: 2–200,000): To enhance data handling, these lakes are organized into 20 archives, each grouping 10,000 lakes (e.g., 0000002-0010000.tar). Each archive contains subdirectories grouped by 1,000 lakes for optimized accessibility. Tier 3. Small-to-Medium Lakes (Hylak_id: 200,001–1,427,688): The remaining lakes are combined into a single large-scale archive (0200001-1427688.tar) for distribution efficiency, with internal subdirectories organized by 10,000 lakes. This dataset is developed and maintained by the Water Environmental Management Lab at the University of Seoul. For inquiries or technical support, please contact YoonKyung Cha ([e-mail]). The dataset is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. For further methodological details and background, users are encouraged to consult the following reference: Yang S., Lee H., Lee G., Gu T., Shin J., Kim T., Cha Y. (2026). GLCD250-MOD: Global Daily 250 m Chlorophyll-a Dataset for Inland Lakes based on MODIS. Scientific Data [In review].