California Water Supply Affected by Atmospheric Sahara Desert Dust

California's water supply may be affected by a phenomenon that sends high-altitude dust swirling thousands of miles across the Pacific from the Sahara. New research shows that the tiny particles could affect how much snow California receives.

In 2009, two similar storms occurred in Sierra, bringing snow and rain. Yet while the systems carried the same amount of water vapor, one produced 40 percent more precipitation than the other. Researchers were baffled at first. Yet after they analyzed ground samples of the rain and snow that were dropped by the wetter storm, they found evidence of why the phenomenon occurred. They discovered an abundance of Asian dust in the samples.

The study, published online in the journal Science, examined samples collected from the Earth's atmosphere. Scientists spent days flying through Sierra storm clouds on a government research plane to collect them while instruments below in the Tahoe National Forest took ground measurements. The researchers then analyzed the samples once they came back down to Earth.

So what does the dust have to do with snow? It turns out that when dust and tiny biological particles were detected in the clouds, there was more rain and snow. In fact, previous research has shown that mineral dust acts as a kind of seed for atmospheric ice, according to the Los Angeles Times. This is key for forming significant amounts of precipitation. Yet the latest findings are the first documented evidence that dust and biological particles from as far away as the Sahara Desert can affect the water cycle in the United States.

In fact, the findings show that the Earth is connected in ways that we have never before considered. Like the massive water currents that mix our planet's oceans, air currents also cycle through Earth's atmosphere. This could mean that incidents that happen across major oceans--such as dust storms--could still affect places nearer to home. With the advent of global warming, more windblown desert dust could swirl into the atmosphere and, in consequence, provide more snow to the Sierra region.