 |
| Air pollution can make storms stronger. (Photo: shutterstock) |
Air Pollution Over Asia Makes Pacific Storms More Intense
In the first study of its kind, scientists have compared air pollution rates from 1850 to 2000 and found that anthropogenic (man-made) particles from Asia impact the Pacific storm track that can influence weather over much of the world.
The team, which includes several researchers from Texas A&M University, has had its work published in the current issue of Proceedings of the National Academy of Sciences (PNAS).
Air pollution can make storms stronger. (Photo: shutterstock)
Yuan Wang, Yun Lin, Jiaxi Hu, Bowen Pan, Misti Levy and Renyi Zhang of Texas A&M’s Department of Atmospheric Sciences, along with colleagues from Pacific Northwest National Laboratory, the University of California at San Diego and NASA’s Jet Propulsion Laboratory, contributed to the work.
The team used detailed pollution emission data compiled by the Intergovernmental Panel on Climate Change and looked at two scenarios: one for a rate in 1850 – the pre-Industrial era – and from 2000, termed present-day.
By comparing the results from an advanced global climate model, the team found that anthropogenic aerosols conclusively impact cloud formations and mid-latitude cyclones associated with the Pacific storm track.
“There appears to be little doubt that these particles from Asia affect storms sweeping across the Pacific and subsequently the weather patterns in North America and the rest of the world,” Zhang says of the findings.
“The climate model is quite clear on this point. The aerosols formed by human activities from fast-growing Asian economies do impact storm formation and global air circulation downstream. They tend to make storms deeper and stronger and more intense, and these storms also have more precipitation in them. We believe this is the first time that a study has provided such a global perspective.”
In recent years, researchers have learned that atmospheric aerosols affect the climate, either directly by scattering or absorbing solar radiation, and indirectly by altering cloud formations. Increasing levels of such particles have raised concerns because of their potential impacts on regional and global atmospheric circulation.
In addition, Zhang says large amounts of aerosols and their long-term transport from Asia across the Pacific can clearly be seen by satellite images.
The Pacific storm track represents a critical driver in the general global circulation by transporting heat and moisture, the team notes. The transfer of heat and moisture appears to be increased over the storm track downstream, meaning that the Pacific storm track is intensified because of the Asian air pollution outflow.
“Our results support previous findings that show that particles in the air over Asia tend to affect global weather patterns,” Zhang adds.
“It shows they can affect the Earth’s weather significantly.”
Yuan Wang, who conducted the research with Zhang while at Texas A&M, currently works at NASA’s Jet Propulsion Laboratory as a Caltech Postdoctoral Scholar.
The study was funded by grants from NASA, the Department of Energy, Texas A&M’s Supercomputing facilities and the Ministry of Science and Technology of China.
For more about the Pacific storm track, go to http://www.gfdl.noaa.gov/isidoro-orlanski-pacific-storm-track.
###
Media contact: Keith Randall, News & Information Services, Texas A&M, at (979) 845-4644;Renyi Zhang at (979) 845-7656; or Yuan Wang (979) 450-9106.
1 Comment to Air Pollution Over Asia Makes Pacific Storms More Intense
Aerosols in atmosphere change weather in North America, says new study.
 |
Buildings in Lianyungang, China, are shrouded in smog on December 8, 2013. Aerosol pollution from Asia is likely leading to stronger cyclones in the Pacific, more precipitation, and warming temperatures at the North Pole.
PHOTOGRAPH BY CHINAFOTO/GETTY IMAGES
|
PUBLISHED APRIL 14, 2014
What happens in Asia doesn't stay in Asia, a new study warns. Pollution from booming economies in the Far East is causing stronger storms and changing weather patterns over the Pacific Ocean, which in turn is changing weather in North America, scientists report.
"Whether the weather [in North America] will change in a good direction or bad is hard to say at this time," says Renyi Zhang, a professor of atmospheric sciences at Texas A&M University in College Station. Zhang is a co-author, along with several scientists from the U.S. and China, of a study released in the Proceedings of the National Academy of Sciences on Monday.
The scientists say pollution from Asia is likely leading to strongercyclones in the midlatitudes of the Pacific, more precipitation, and a faster movement of heat from the tropics toward the North Pole. As a result of these changes, "it's almost certain that weather in the U.S. is changing," says Zhang.
Smaller Drops, Bigger Storms
Zhang and his colleagues used computer modeling to study the effects on the weather of aerosols, which are fine particles suspended in the air. The main natural aerosols over the Pacific are sea salt tossed up by waves and dust blown off the land.
But those natural particles are now increasingly outnumbered by human-made ones. According to Zhang, the most significant aerosols the team considered are sulfates, which are emitted primarily by coal-fired power plants. Other aerosol pollutants are released by vehicle emissions and industrial activities.
In the atmosphere, such aerosols scatter and absorb sunlight, and thus have both cooling and warming effects on climate. But they also affect the formation of clouds and precipitation—and the magnitude of that indirect effect on clouds is one of the biggest uncertainties hampering scientists' ability to forecast climate change.
Clouds form when water vapor condenses around aerosol particles to form liquid droplets. Because pollution increases the number of particles, it leads to more water droplets—but smaller ones. Those smaller droplets in turn rise to greater heights in the atmosphere—and even form ice—before they precipitate back out.
In an earlier paper, Zhang and his colleagues used satellite data to show that the amount of "deep convective clouds," including thunderstorms, had increased over the North Pacific between 1984 and 2005. The most likely reason, they concluded, was an increase in aerosol pollution from Asia. "The intensified Pacific storm track likely has profound implications for climate," they wrote.
Global Effects
In the recent study the scientists took a first stab at considering those global implications. Standard global climate models simulate the atmosphere at grid points that are too widely spaced to resolve the fine-scale processes involved in cloud formation—which is one reason clouds remain such a knotty problem for climate scientists. But the researchers found a way to embed a "cloud resolving model" into a conventional climate model.
They then used that "multiscale" model to compare the preindustrial atmosphere of 1850, when levels of aerosol pollution over the Pacific were low, with the present atmosphere.
The simulations confirmed that human-made aerosols are now spreading across the Pacific and having large effects on the storms that sweep east during winter. The storms are more vigorous than they would be without pollution, with more ice and a broader "anvil" shape to the cloud tops. And those more vigorous storms are having a significant effect on the global atmosphere: They're increasing the flow of heat from the equatorial region toward the Arctic, says Zhang.
What about North America? The Pacific storm track has a big effect on American weather, and large-scale natural changes like El Niño and La Niña are known to disrupt its usual pattern, leading to floods and droughts.
"What we have shown is that aerosols from Asia can get transported over the Pacific and change weather in North America," Zhang says—but nailing down the nature of the change will require more research.
"We've been getting some weird weather, such as a very cold winter [in the eastern U.S.], so the next question is, does that have something to do with Asian pollution?"
http://news.nationalgeographic.com/news/2014/04/140414-asia-pollution-aerosols-atmosphere-weather-climate-science/
Supercomputer Shows How Air Pollution from Asia Worsens Pacific Storms
Scientists have used a supercomputer to compare air pollution rates from 1850 to 2000, and discovered that man-made particles from Asia are making Pacific storms more intense, which can impact weather around the world.
“The aerosols formed by human activities from fast-growing Asian economies do impact storm formation and global air circulation downstream,” says Renyi Zhang, a professor in Texas A&M’s department of atmospheric sciences in a recent press release. “They tend to make storms deeper and stronger and more intense, and these storms have more precipitation in them.”
The effect of the pollutants is more pronounced during winter, according to a BBC News article. Parts of Asia has some of the highest levels of air pollution in the world with Beijing, China frequently reaching hazardous levels and Delhi, India regularly reaching emissions levels that are higher than recommended by the World Health Organization, the story said.
The scientists used the Texas A&M Supercomputing Facility to analyze the climate data. According to their research, polluting particles from Asia are blown toward the north Pacific, where they interact with water droplets in the air. That causes clouds to grow denser, resulting in more intense storms, the BBC story said.
Zhang performed the study with five other researchers from Texas A&M’s Department of Atmospheric Sciences as well as researchers from the Pacific Northwest National Laboratory, UC San Diego an NASA’s Jet Propulsion Laboratory. The research was published in a recent issue of Proceedings of the National Academy of Sciences.
Nenhum comentário:
Postar um comentário