NASA’s Aquarius Satellite Will Help Scientists Learn About Salt Levels in the Sea

STEVE EMBER: I’m Steve Ember.
DOUG JOHNSON: And I’m Doug Johnson with EXPLORATIONS in VOA Special English. Today we tell about an American space agency project to study salt levels in the Earth’s oceans. We report on plans to collect rock particles from a nearby asteroid. And we tell about a discovery of huge magnetic bubbles in space.
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STEVE EMBER: On June tenth, the National Aeronautics and Space Administration, NASA, launched a satellite called Aquarius. The satellite will measure and study the saltiness of Earth’s oceans from space. The aim of the project is to learn about our changing climate. The project is a joint effort between NASA and Argentina’s space agency.
Some satellites orbiting the Earth provide information about sea temperatures and depths. Others gather information about the ocean’s color and winds. But there has never before been a worldwide study of the salt levels of the sea surface.
Until now, this kind of information came only from ships and buoys floating in the ocean. Experts say Aquarius will gather as much information about sea surface salinity as has been collected by ships over the past one hundred twenty-five years.
DOUG JOHNSON: NASA officials say the project will give scientists a better understanding of Earth’s changing climate. They say it should provide missing information about the water cycle and the circulation, or movement, of ocean waters. These two forces are a major influence on the ocean’s climate. Experts say the salt measurements will provide the information that links these forces within the climate system.

The Earth’s water cycle is the continuous movement of water as it changes from a liquid to a vapor or gas. Water from the sea rises up as vapor to form clouds before changing to rain or snow. Most of the planet’s evaporation and precipitation take place over oceans. Understanding salt levels will help experts better understand how increases and decreases of fresh water from rain affect the ocean environment.
STEVE EMBER: When scientists study the circulation of ocean water, they are looking at how the water mass of the ocean forms layers and mixes together. This mixing is a product of the oceans’ density and buoyancy. These, in turn, depend on the water’s temperature and saltiness. Buoyancy is the upward force that a liquid places on an object that is less dense than itself. Knowing about salt levels helps tell scientists more about the ocean water movement.
Scientists will use salt water measurements to understand how the ocean’s climate is changing. Gary Lagerloef works for the Earth and Space Research Institute in Seattle, Washington. He is the main investigator of the Aquarius project. He says information gathered by Aquarius will show how the ocean environment is changing.
GARY LAGERLOEF: “One of the big overarching questions in climate is, is the global water cycle changing? Many climate forecasting models suggest that it will change over time as the climate warms up. But measuring these changes in rainfall over the ocean is very, very difficult to do. But salinity is actually an important parameter that gives us an indication of what might be going on.”
DOUG JOHNSON: Aquarius will also produce maps of saltwater movement around the world every month. The satellite is equipped with microwave radiometers. These measuring devices must be very exact and secure to provide detailed information.
Yi Chao is a scientist with the Aquarius project at NASA’s Jet Propulsion Lab in California.