The “Magic Dust” that Brings More Sierra Snow

Dust from across the Pacific seeds Sierra snowflakes

Molly Samuel

Researchers found that heavy snowfall in the Sierra is connected to the amount of dust floating over from Asia.

In a weird twist on the “butterfly effect,” evidence is that Asian dust storms can mean more snow in the Sierra. The strange finding surfaced in research by scientists working on NOAA’s CalWater program. Scientists compared two Sierra storms, and found the one that contained dust particles from Asia had 40% more precipitation than the one that did not. The other storm had more particulate matter from sources in California, for instance, from burning trees or grass.

The researchers, including Kim Prather and Doug Collins from the Scripps Institute of Oceanography at UC San Diego compared the two storms from the air.

In a series of test flights, scientists flew a zig-zag pattern from the former McClellan Air Base, east of Sacramento, toward the Sierra, using a specially outfitted C-130 research aircraft based at the National Center for Atmospheric Research in Boulder, Colorado.

NCAR

A C-130 research aircraft was outfitted with special probes to collect cloud droplets and ice particles during the cloud fly-throughs.

Prather, who directs the Center for Aerosol Impacts on Climate and the Environment at UC San Diego, said there’s still a lot to learn about the precise “interfacial” chemistry that goes on among cloud particles. Only one particle in a thousand is likely to become an ice crystal, the basic building block of snow. Prather says there’s “something chemically magical about ice crystals.” Apparently so, as clouds remain one of the most difficult aspects of climate modeling. “Aerosols” is the term scientists use to refer to all sorts of particulate matter drifting around in the air.

After a Friday presentation at the American Association for the Advancement of Science (AAAS) in Vancouver, Prather told me that no flights were scheduled this winter because of the unusual dearth of rain clouds, but that they planned to resume cloud-probing flights next winter.

The dust connection is another piece to the California water puzzle, and will help researchers better understand why we get precipitation when we do, and help them make better projections.

There’s more about the research in this article from the Bay Citizen.