New tech helps measure Sierra snowpack from the sky

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Tuesday, March 3, 2015
New tech helps measure Sierra snowpack from the sky
New technology is giving California water officials a view of the Sierra snowpack that they've never had before, and ABC7 News got an insider's look at it.

SAN FRANCISCO (KGO) -- When state water officials measure the Sierra snowpack on Tuesday, they'll do it the same way they've been doing it for more than a century. It'll give us a snapshot of the drought. But new technology is giving them a view they've never had before and ABC7 News got an insider's look at it.

Frank Gehrke, chief of California Cooperative Snow Surveys Program for the Department of Water Resources, has been measuring snow density in the Sierra Nevada for more than three decades.

"The accumulated snow in the mountains is the principal water supply for the entire Western U.S," he said.

But his monthly pole measurements only give a snapshot of conditions at a single location. He would need to plant thousands of poles across the Sierra to get an accurate picture of the entire region. That would be impossible, until now.

ABC7 News got a look at the world's first Airborne Snow Observatory, or flying snow pole.

"What we've essentially done with the aircraft and the Airborne Snow Observatory is, in each mountain basin, put about 39 million times more of those," said Thomas Painter with NASA's Jet Propulsion Laboratory.

The state teamed up with NASA's Jet Propulsion Laboratory in Pasadena to make this happen. ABC7 News caught up with researchers between flights outside of Sacramento.

Onboard, high tech tools; an imaging spectrometer tells scientists how fast the snowpack will melt. LIDAR sends out a pulsing infrared laser to measure the depth of the snow. Together they provide a 3-D map of the Sierra snowpack.

"Our scanning LIDAR is spraying out in this case, about 200,000 pulses of light per second," Painter said. "Touching all of these trees and snow and then returning and telling us where the surface is so that we can know what the difference is in that topography."

In just four hours, the Airborne Snow Observatory zigzags over hundreds of miles. From thousands of feet in the air, it measures snow depths on the ground within 4 inches.

"It can go from zeo feet of snow to 30 feet of snow over a very short distance," said Painter.

Gehrke added, "If you can improve your forecast accuracy, you can much more efficiently manage the reservoir capacity that we do have in existence."

Last year, researchers surveyed the Hetch Hetchy watershed, the source of water for more than two million people in the Bay Area. The reservoir also helps generate clean power for the city of San Francisco. The data they collected showed how much and how fast the snow melted, giving water officials an upper hand.

"They could not only ensure that the reservoir was full come the end of snow melt, but also were able to increase their power generation," said Gehrke.

The program started just two years ago. And at a cost of about $1 million per season, it isn't cheap. Most of the costs are absorbed by NASA. But state water officials say the price is just a drop in the bucket at a time when the bucket is already nearly dry.

A preliminary analysis confirms what we already know -- there isn't much snow, even at the highest elevations. Although, they did get some over the weekend, which helped a little.

For full coverage on the drought, click here.