Transcripts of Pacific_aerosol_transport_G2012_086_youtube_hq



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[music] Narrator: New satellite data show that every year, 64 million tons of airborne particles arrive in North American airspace from foreign sources, almost as much those produced domestically. These particles are called aerosols, a broad term that includes particulate pollution, soot from fires, salt from the ocean, grains of pollen, volcanic ash, and dust from deserts. And as it turns out the vast majority of these imported aerosols are in the and arrive in North America via air currents over the Pacific Ocean. For years researchers have used increasingly powerful computer models to simulate the transport of aerosols around the globe. But we had no good way of measuring how much of this aerosol mass was produced at home and how much came from abroad, how much was pollution and how much was dust, or how high these particles were in the atmosphere, all important factors in assessing aerosols’ impacts on air quality and Earth’s climate. Now a new analysis of NASA satellite data has given us some surprising answers. Remer: The first was that half of the particles that are above North America come from someplace else. And that’s a big number, half. I wasn’t expecting anything like that. The second piece was that even though these particles are coming from someplace else, they come in high in the atmosphere. They’re not on the ground, so we’re not breathing them. And the third piece of the study I found really surprising, that most of it is dust and natural aerosol, not manmade aerosol. And again, that, that has implications for if you’re trying to control how much pollution goes from one continent to the next, from one country to the next, even if you turned off all the industry everywhere else, we would still have all these foreign particles in our air shed above us because it’s, it’s natural.But as it turns out, we should still keep focused on our own pollution in order to keep our air healthy because the particles that come from other places come high. Narrator: Besides direct impacts on human health, we need to better understand how the movement of aerosols affect weather and climate. For example, some aerosols can change precipitation patterns by while other dust and soot particles can build up on snow surfaces and have local effects. Yu: That could make snow darker and easier to melt. So this could have a significant impact on the water supply Narrator: The imported aerosols primarily reflect sunlight, resulting in a cooler Earth-atmosphere system that partly compensates for the larger warming effect of greenhouse gases. Some imported aerosols actually like dust and soot absorb sunlight and heat the local atmosphere. Yu: This could change atmospheric circulations and it could have a significant impact on weather and climate. I think the take home message is  So, that's my take home message 

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