(Bloomberg Business) — A team of scientists atNASA's Jet PropulsionLaboratory is tracking California's snowpack levelsaboard a flying laboratory.

It's called the Airborne Snow Observatory—a Beachcraft King Airturboprop plane with two key instruments on board measuring howmuch snow is on the ground through a hole in the belly of theaircraft.

Snowpack supplies about 70 percent of California's annualprecipitation, according to NASA, making it crucial to the watersupply of a state that's experiencing a four-year drought.

"It's unbelievably extreme compared to anything we have onrecord," says Frank Gehrke, chief of California cooperative snowsurveys for the California Department of Water Resources. "Where wewould normally have 5, 6, 10 feet of snow, we're seeing bareground."

"Water managers in these mountains always need to know how muchsnow pack there is, how quickly it's coming out, how quickly it'sgoing to come out, and how much total there is going to be," saysTom Painter, the principal investigator and lead scientist for theprogram. "We can let them know exactly how much water thereis."

Painter and his team cycle through a rotation, flying three tofour times a week over different basins in California andColorado. They measure the snow depth using a scanningLidar—a high-frequency laser that scans the ground 800,000 times asecond. By tracking how quickly each pulse bounces back to theplane, they can tell the depth of the snow below.

They also use an imaging spectrometer, which measures sunlightin 100 different colors and tells the scientists how much sunlightis being reflected by the snow. From those data they can calculatehow much water there will be when the snowpack melts. They thentransfer that data to various water managers throughout thestate.

"The various water managers that we are working with closelywatch this information, they use it in their models, they use it intheir decision-making with respect to allocation of water, and thenknowing what the likely scenario is going to be over the next monthas the last little bits of snow melt away," Painter says.

The Airborne Snow Observatory program is a partnership betweenNASA's Jet Propulsion Laboratory and the California Department ofWater Resources. Next steps include expanding coverage throughoutthe Western U.S. into Colorado, Wyoming, Utah, and New Mexico andultimately expanding the program internationally.

"To know that we are taking care of the most critical resourcefor this part of the world and, as we expand the program to otherparts of the world, that we'll be taking care of the waterresources for all those people, a billion and a half peopleworldwide, it's a good feeling to be able to bring the technologyfor that purpose," Painter says.