January 27, 2014

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Haze in the Sichuan Basin, as seen from space

Much like the Los Angeles basin, China’s Sichuan Basin traps haze and smog. NASA’s Terra satellite capture the following image of a hazy Sichuan Basin on January 23, 2014: The Sichuan Basin is home to many cities, including the province’s capital Chengdu, a city with more than 14 million residents.

By David Wogan

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This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

Much like the Los Angeles basin, China's Sichuan Basin traps haze and smog. NASA's Terra satellite capture the following image of a hazy Sichuan Basin on January 23, 2014:

The Sichuan Basin is home to many cities, including the province's capital Chengdu, a city with more than 14 million residents.

Haze is trapped in the basin because of a temperature inversion. The same process that gives us beautiful fog in the Grand Canyon also works for pollutants. Earth Observatory explains:

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Haze in this region tends to worsen in the winter, when cold, heavy air traps pollutants near the surface. In this case, the haze was likely trapped in the Sichuan Basin by a temperature inversion. Normally, air is warmest near the surface of the Earth. Occasionally, a mass of warm air will move over cooler air so that the atmosphere actually warms with altitude. Since the cool air does not have the energy to rise through the warm air, vertical circulation slows and air becomes trapped near the surface.

Any pollutant that enters the air gets trapped as well, and haze builds up over time. Temperature inversions often form in basins and valleys because surrounding higher-elevation land helps contain cold air. Daily imagesof the Sichuan Basin show that that the pollution has persisted for several days.

For a look at what the Basin looks like without a blanket of haze you can head over to Google Maps.

David Wogan is an engineer and policy researcher who writes about energy, technology, and policy.

David's academic and professional background includes a unique blend of technology and policy in the field of energy systems. Most recently, David worked at Austin Energy, a Texas municipal utility, implementing a Department of Energy stimulus grant related to energy efficiency. Previously, David was a member of the Energy & Climate Change team at the White House Council on Environmental Quality for the Obama Administration.

David holds two Master's degrees from The University of Texas at Austin in Mechanical Engineering and Public Affairs. While at UT, David was a researcher in the Webber Energy Group, where his research focused on advanced biofuel production to offset petroleum use in the transportation sector. David holds a Bachelor's of Science degree in Mechanical Engineering from The University of Texas at Austin, where he researched nuclear non-proliferation measurement technology.

David is a 2013 Aspen Institute Journalism Scholar, joining a select group of journalists from Slate, ABC News, and The New York Times.

David lives in Austin, Texas. Follow along on Twitter or email him at david.wogan@me.com.

More by David Wogan

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