For Nearly 20 Years, GRACE Has Helped Us Understand Climate Change

In 2002, two satellites designed to take detailed measurements of the Earth were launched into space. The Gravity Recovery And Climate Experiment — GRACE for short — was intended to operate for no more than 5 years, yet it continued sending back critically needed data for nearly 15 years. The mission was a collaboration between NASA and the German Aerospace Center and was led by researchers in the Center for Space Research at the University of Texas’ Cockrell School of Engineering.

Credit: JPL/NASA

During its operational lifespan, GRACE provided unprecedented insight into global water resources, from more accurate measurements of polar ice loss to a better view of the ocean currents and the rise in global sea levels. Much of the data it returned to the scientists waiting on Earth has proved vital to understanding the extent to which climatic changes have occurred since the GRACE program began.

Bryan Tapley established the Center for Space Research in 1981 and has served as the principal coordinator of the GRACE program. By measuring changes in mass that cause deviations in the strength of gravity’s pull on the Earth’s various systems — water systems, ice sheets, atmosphere, land movements, and more — the satellites can measure small changes in the Earth system interactions, he tells Science Daily.

“By monitoring the physical components of the Earth’s dynamical system as a whole, GRACE provides a time variable and holistic overview of how our oceans, atmosphere and land surface topography interact. The concept of using the changing gravimetric patterns on Earth as a means to understanding major changes in the Earth system interactions had been proposed before,” he says, “but we were the first to make it happen at a measurement level that supported the needs of the diverse Earth-science community.”

The Texas Advanced Computing Center at the University of Texas has played a vital role in the GRACE program. Tapley says TACC made it possible to pose questions whose solutions would have not been feasible without it.

“As an example, when we began the GRACE mission, our capability was looking at gravity models that were characterized by approximately 5,000 model parameters, whose solution was obtained at approximately yearly analysis intervals.

“The satellite-only GRACE models today are based on approximately 33,000 parameters that we have the ability to determine at a daily interval. In the final re-analysis of the GRACE data, we’re looking to expand this parameterization to 4,000,000 parameters for the mean model. The interaction with TACC has always been in the context of: ‘If the answer to a meaningful question requires extensive computations, let’s find a way to satisfy that requirement.'”

The data from GRACE is processed through TACC and shared with the Geophysics Center in Potsdam and the NASA Jet Propulsion Laboratory in Pasadena. “The collection of information from this international community are brought together by the fundamental computing capability and the operational philosophy at TACC to undergo the challenging data analysis required to obtain the paradigm-shifting view of the Earth’s interactions,” Tapley says.

Now, a new program called the GRACE Follow-On mission has launched successfully. It will allow researchers to  create a second multi-decadal measurement of changes in mass across the Earth. Engineers and scientists anticipate the longer data interval will allow them to see an even clearer picture of how the planet’s climate patterns behave over time.

Now if only we could dispel the notion that all those researchers are agenda driven fat cats chasing around after public and private grant money to pad their own wallets, perhaps the world would stop perseverating about Al Gore and get to work finding solutions to a rapidly warming planet. Who started those scurrilous rumors anyway? Oh, right. Charles and David Koch and ExxonMobil. Thanks, guys, for destroying our planet in your single minded pursuit of personal financial gain.