A collaborative group of researchers at Columbia Engineering and Boston University has successfully developed a method for mapping evaporation. The study was recently published in the online Early Edition of the Proceedings of the National Academy of Sciences (PNAS) and shows how data collected from weather stations can be used to measure evaporation.

A simple model of the hydrologic cycle includes three main components: precipitation, runoff and evaporation (in various forms) (Figure 1). To date, scientists have focused on measuring precipitation using rain gauges and microwave remote sensing, while measuring runoff using stream-flow measurements.

However, accurately measuring evaporation is viewed as a challenging problem. In a Columbia Engineering news release, Pierre Gentine, assistant professor of Earth and environmental engineering, stated ‰ÛÏglobal measurements of evaporation have been a long standing and frustrating challenge for the hydrologic community.‰Û Despite its elusive nature, evaporation is the key to fully understanding the cycle.

Now, Gentine in collaboration with Guido D. Salvucci at Boston University, has for the first time filled the knowledge gap on the cycle by analyzing air temperature and humidity measurements that were already acquired from weather stations. By realizing the potential for accurate measurements, the group will now continue its research by mapping levels of evaporation. Confirming the results, Gentine states that researchers will now ‰ÛÏbe able to map evaporation in a consistent way, using concrete measurements that are available around the world.‰Û

From here, Gentine and Salvuccia will continue to use these datasets to create maps of evaporation. Prospective uses will be far-reaching in areas such as agriculture and climate change research. Gentine states that ‰ÛÏsharing our data with researchers around the world will help us learn more about the Earth’s hydrologic cycle and assess recent trends such as whether it is accelerating.‰Û