Soil Moisture Active Passive (SMAP): SMAP: The Dirt Behind Improved ForecastingFebruary 2nd, 2015 by Rani Gran, NASA's Goddard Space Flight Center
Dara Entekhabi has been waiting 15 years for this moment—the launch of NASA’s Soil Moisture Active Passive (SMAP) satellite from Vandenberg Air Force Base in California. Even a snowstorm wasn’t going to stop him: He flew out of Boston just before a major storm dumped over 30 inches of snow on his home.
The satellite, which launched early in the morning of January 31, could aid in studying storms like that in the future. “Next year, if the East Coast sees another major Nor’easter snowstorm, forecasters will be able to predict the flood potential with greater accuracy,” said Entekhabi, lead scientist for SMAP at the Massachusetts Institute of Technology, Cambridge.
That’s because SMAP can measure how much water the ground can absorb. If the ground is frozen, the soil will not be able to absorb much water from snowmelt. Some of the worst floods occur when it rains on snow. “Its like you suddenly tip a water bucket,” he said.
Since 1999, Entekhabi has advocated for improving weather forecasts with dedicated satellite measurements of soil moisture. Previous investments in higher resolution satellite measurements led to improvements to weather forecast models. But there are other fronts to explore to improve forecasts’ accuracy further.
SMAP’s global look at soil moisture is one of the leading contenders, Entekhabi said. When scientists ran test forecasts using historical conditions, the computer models that integrated realistic surface soil moisture information produced a more accurate forecast. From this result, researchers realized an investment in better soil moisture measurements would provide significant improvements in weather forecasting.
With this knowledge, Entekhabi began the campaign of building advocacy among the science community for a dedicated soil moisture satellite mission. The SMAP mission—a collaboration between the Jet Propulsion Laboratory, NASA Goddard, and science team members from various institutions—has had ups and downs along the road to launch.
“It’s been a long haul,” Entekhabi says. “But I live this every day and I can’t imagine doing anything else.”