GLOBMAP SWF: Global Annual Surface Water Cover Frequency Since 2000

296 global tiles at 500 m spatial and annual temporal resolution from 2000 to 2020. The dataset provides surface water cover frequency (SWF), defined as the percentage of time a pixel is covered by water in a year, derived from MODIS land surface reflectance products. It was generated by Ronggao Liu of the Chinese Academy of Sciences to analyze seasonal and interannual dynamics of inland water bodies.

Use Cases

• Analyzing interannual variation and change trends of inland water body extent based on annual SWF values.
• Studying the seasonal dynamics of surface water in regions with high variability based on the cover frequency metric.
• Monitoring changes in water bodies due to climatic factors and human activities across different global regions.
• Assessing algorithm performance for specific challenging conditions like frozen water, saline lakes, or bright surfaces as mentioned in the description.

Strengths

• Covers 21 years (2000-2020) of global data, providing a long-term time series for trend analysis.
• Uses a 500 m spatial resolution and is divided into 296 standardized 1200 km x 1200 km tiles for manageable processing.
• The SWF algorithm is designed to reduce the influence of clouds and variable surface characteristics, improving applicability across different regions.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Last update date is unknown; freshness unverified.
• The dataset's specific validation metrics or error rates for different regions are not detailed in the provided description.

Provenance

Source

Chinese Academy of Sciences

Collection Method

Generated from MODIS land surface reflectance products using an algorithm that identifies land observations among annual clear-sky observations.

Time Range

2000-2020

Freshness

Data covers up to 2020; last update date for the dataset record is unknown.

Geography

Global