New technique measures evaporation globally

Apr 11, 2013

Researchers at Columbia Engineering and Boston University have developed the first method to map evaporation globally using weather stations, which will help scientists evaluate water resource management, assess recent trends of evaporation throughout the globe, and validate surface hydrologic models in various conditions. The study was published in the April 1 online Early Edition of Proceedings of the National Academy of Sciences (PNAS).

"This is the first time we've been able to map evaporation in a consistent way, using concrete measurements that are available around the world," says Pierre Gentine, assistant professor of earth and environmental engineering at Columbia. "This is a big step forward in our understanding of how the water cycle impacts life on Earth."

The Earth's surface hydrologic cycle comprises precipitation, runoff, and evaporation fluctuations. Scientists can measure precipitation across the globe using rain gauges or microwave remote sensing devices. In places where streamflow measurements are available, they can also measure the runoff. But measuring evaporation has always been difficult.

" of evaporation have been a longstanding and frustrating challenge for the hydrologic community," says Gentine. "And now, for the first time, we show that simple weather station measurements of air temperature and humidity can be used across the globe to obtain the daily evaporation."

Evaporation is a key component of the : it tells us how much water leaves the soil and therefore how much should be left there for a broad range of applications such as agriculture, , and weather forecasting.

Gentine, who studies the relationship between hydrology and atmospheric science and its impact on climate change, collaborated on this research with Guido D. Salvucci, professor and chair of the Department of Earth and Environmental Sciences at Boston University and the paper's lead author. Using data from , widely available across the globe, they focused on evaporation and discovered an emergent relationship between evaporation and relative humidity that gave them the evaporation rates.

Gentine and Salvucci plan to provide daily maps of evaporation around the world that will enable scientists to evaluate changes in water table, calculate water requirements for agriculture, and measure more accurate evaporation fluctuations into the atmosphere.

"Sharing our data with researchers around the world will help us learn more about the Earth's and assess recent trends such as whether it is accelerating," adds Gentine. "Acceleration could greatly impact our climate, locally, nationally, and globally."

Explore further: Better forecasts for sea ice under climate change

More information: Paper: www.pnas.org/content/early/201… /1215844110.abstract

Related Stories

Water evaporated from trees cools global climate

Sep 14, 2011

Scientists have long debated about the impact on global climate of water evaporated from vegetation. New research from Carnegie's Global Ecology department concludes that evaporated water helps cool the earth as a whole, ...

Land use change influences continental water cycle

Jun 28, 2011

Forests, and tropical forests in particular, play an important role in the global water cycle. Delft University of Technology PhD researcher Ruud van der Ent (TU Delft, The Netherlands) has recently shown that evaporation ...

Big uncertainties in the global water budget

Jun 13, 2012

No life without water. Catastrophes like droughts or strong rains reflect our dependence on the water cycle and climate system. Hence, it is important to understand details of the water cycle among the atmosphere, ...

Recommended for you

Better forecasts for sea ice under climate change

1 hour ago

University of Adelaide-led research will help pinpoint the impact of waves on sea ice, which is vulnerable to climate change, particularly in the Arctic where it is rapidly retreating.

"Ferrari of space' yields best map of ocean currents

9 hours ago

A satellite dubbed the "Ferrari of space" has yielded the most accurate model of ocean circulation yet, boosting understanding of the seas and a key impact of global warming, scientists said Tuesday.

Researcher studies deformation of tectonic plates

12 hours ago

Sean Bemis put his hands together side by side to demonstrate two plates of the earth's crust with a smooth boundary running between them. But that boundary is not always smooth and those plates do not always ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

MikPetter
not rated yet Apr 15, 2013

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.