New NASA Salt mapper to sharpen climate forecasts

NASA: Salt is essential to human life. Most people don't know, however, that salt -- in a form nearly the same as the simple table variety -- is just as essential to Earth's ocean, serving as a critical driver of key ocean processes. While ancient Greek soothsayers believed they could foretell the future by reading the patterns in sprinkled salt, today's scientists have learned that they can indeed harness this invaluable mineral to foresee the future -- of Earth's climate.

The oracles of modern climate science are the computer models used to forecast climate change. These models, which rely on a myriad of data from many sources, are effective in predicting many climate variables, such as global temperatures. Yet data for some pieces of the climate puzzle have been scarce, including the concentration of dissolved sea salt at the surface of the world's ocean, commonly called ocean surface salinity, subjecting the models to varying margins of error. This salinity is a key indicator of how Earth's freshwater moves between the ocean, land and atmosphere.

Enter Aquarius, a new NASA salinity-measurement instrument slated for launch in June 2011 aboard the Satélite de Aplicaciones Científicas (SAC)-D spacecraft built by Argentina's Comisión Nacional de Actividades Espaciales (CONAE). Aquarius' high-tech, salt-seeking sensors will make comprehensive measurements of ocean surface salinity with the precision needed to help researchers better determine how Earth's ocean interacts with the atmosphere to influence climate. It's a mission that promises to be, to quote the old saying, "worth its salt."

"We ultimately want to predict climate change and have greater confidence in our predictions. Climate models are the only effective means we have to do so," said Aquarius Principal Investigator Gary Lagerloef, a scientist at the Seattle-based independent laboratory Earth & Space Research. "But, a climate model's forecast skill is only as good as its ability to accurately represent modern-day observations."

Density-driven ocean circulation, according to Lagerloef, is controlled as much by salinity as by ocean temperature. Sea salt makes up only 3.5 percent of the world's ocean, but its relatively small presence reaps huge consequences….

Global differences, on average, between evaporation and precipitation, the main elements of the global water cycle. Eighty-six percent of global evaporation is from the ocean surface, and 78 percent of global precipitation falls back over the ocean. Changes in these patterns affect the salinity of the ocean surface. Scientists will incorporate Aquarius salinity data into computer models used to improve predictions of future climate. Image credit: Committee on Earth Observation Satellites