Team Uses Satellite To Track Earth’s Water

For the first time, scientists have used a space-home instrument to track the origin and movements of water vapor throughout Earth’s atmosphere, providing a new perspective on the dominant role Earth’s water cycle plays in weather and climate.

A team of scientists from the University of Colorado at Boulder and NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., used the tropospherie emission spectrometer on NASA’s Aura satellite to gather data on heavy and light water vapor in order to retrace the history of water over oceans and continents, from ice and liquid to vapor and hack again. The researchers were able to distinguish between the two because heavy water vapor molecules have more neutrons than lighter ones do.

By analyzing the distribution of the heavy and light molecules, the team was able to deduce the sources and processes that cycle water, the most abundant greenhouse gas in Earth’s atmosphere, said David NooneofCUBoulder’s Cooperative Institute for Research in Environmental Sciences.

The team found that tropical rainfall evaporation and water "exhaled" by forests are key sources of moisture to the tropical atmosphere. The researchers noted thai much more water man expected is transported inio the lower troposphere over land than over oceans, especially over the Amazon River basin and in tropical Africa.

"One might expect most of the water to come directly from the wet ocean," said Noonc. "Instead, it appears that thunderstorm activity over the tropical continents plays a key role in keeping the troposphere hydrated."

The team found that in the tropics and regions of tropical rain clouds, rainfall evaporation significantly adds moisture to the lower troposphere, with typically 20 percent, and up to 50 percent, of rain ihere evaporating before it reaches the ground.

The strength and location of such evaporation gives scientists new insights into how water in Earth’s atmosphere helps move energy from Earth’s surface upward, important since the main role of the atmosphere in Earth’s climate system is to take energy deposited by the sun and return it to space, said Noone.

Copyright Compass Publications, Inc. Mar 2007

(c) 2007 Sea Technology. Provided by ProQuest Information and Learning. All rights Reserved.