For 24 years, eight satellites have watched water vapor move around Earth—but their measurements were scattered across different formats and locations. WISO-SAT, a new open database, brings those records together so researchers can compare them as one much easier-to-use source.
The measurements track water isotopes: forms of water molecules that have slightly different masses. The balance of heavier and lighter isotopes can act like a clue to where water came from and what it has passed through. That information helps scientists follow the water cycle, from moisture moving through the air to the formation of clouds and changes in rainfall.
Eight satellite missions have measured water vapor isotopes around the planet from 2002 to the present. But each mission was built to answer somewhat different questions, and each recorded its measurements in its own way. Although the satellites were studying the same basic feature, putting their data side by side could take months of work. Comparing just two missions could cost researchers a year of cleaning and matching records before they could begin their scientific analysis.
That made it harder to see the full picture—and meant research teams in different parts of the world might repeat the same time-consuming work. Satellites are especially valuable because they can observe places field researchers cannot easily reach and gather measurements over long periods. Sylvia Dee, an associate professor at Rice University, said scientists needed to treat the records as one data set to make them a strong resource for understanding the water cycle.
Mampi Sarkar, a research scientist at Rice, led the effort with experts from NASA in the United States, as well as teams in Europe and Japan. Their database, called WISO-SAT, collects, cleans and standardizes data from all eight missions across the 24-year record. The experts who worked on the project brought knowledge of individual satellites, including how each one gathered and recorded its measurements.
Sarkar also built a publicly available process, or pipeline, for preparing the data. The measurements are placed on a shared grid and described in a consistent way, while accounting for differences between satellite instruments. Researchers can see where each measurement was taken and understand what it represents, regardless of which mission produced it. The database and its instructions are open to researchers worldwide, and the pipeline can help others prepare and submit similar data in the future.
The new resource could help researchers investigate cloud formation, the movement of moisture, El Niño and La Niña, deforestation and soil moisture. Those topics connect water movement to weather, ecosystems and changing conditions on land. WISO-SAT does not answer those questions on its own; instead, it gives more researchers a common starting point and saves them from rebuilding the same comparison tools.
The database was described in the journal Scientific Data in a 2026 paper by Mampi Sarkar and colleagues, titled “WISO-SAT: A global database of stable hydrogen isotopes in water vapor from eight satellite missions.” By making decades of satellite observations easier to find and compare, the team has turned a difficult-to-use archive into a resource that can support new questions about how water moves across Earth.