Amazon rainforest provides a unique natural lab to study the effects of aerosols
Tiny airborne particles can have a stronger influence on powerful storms than scientists previously predicted, according to a new study co-authored by University of Maryland researchers. The findings, published in the January 26, 2018 issue of the journal Science, describe the effects of aerosols, which can come from urban and industrial air pollution, wildfires and other sources.
While scientists have known that aerosols may play an important role in shaping weather and climate, the new study shows that the smallest of particles have an outsized effect. Particles smaller than one-thousandth the width of a human hair can intensify storms, increase the size of clouds and cause more rain to fall.
"This result adds to our knowledge of the interactions between aerosols, clouds and precipitation. In areas where aerosols are otherwise limited, such as remote regions of the Amazon rainforest, ultrafine aerosol particles can have a surprisingly strong effect," said Zhanqing Li, a professor of atmospheric and oceanic science at UMD and a co-author of the study. "This finding will help us better understand the physical mechanisms of cloud development and severe storm formation, which can help us develop better storm prediction methods."
The findings are largely based on data from the international Green Ocean Amazon research campaign, including ground-based and airborne measurements of rainforest climate and water cycling collected during the study period, which spanned 2014 to 2015.
The study focused on an area of the Amazon that is pristine except for the region around Manaus, Brazil, the largest city in the Amazon, with a population of more than 2 million people. This setting gave the researchers a rare opportunity to look at the impact of pollution on atmospheric processes in a largely pre-industrial environment, isolating the effects of the particles from other factors such as temperature and humidity.
"We showed that the presence of these particles is one reason why some storms become so strong and produce so much rain," said Jiwen Fan, an atmospheric scientist at the Department of Energy's Pacific Northwest National Laboratory and the lead author of the study. "In a warm and humid area where atmospheric conditions are otherwise very clean, the intrusion of very small particles can make quite an impact."
The researchers studied the storm-creating capacity of ultrafine particles that measure less than 50 nanometers across. For reference, a typical human red blood cell is about 8,000 nanometers wide.
Larger particles are known to play a role in feeding powerful, fast-moving updrafts of air, which create clouds that form water droplets that fall as rain. But until now, scientists had not observed smaller particles, such as those contained in vehicle exhaust and industrial smog, exerting the same effect.
Using detailed computer simulations, the researchers showed how smaller particles can invigorate clouds in a much more powerful way than their larger counterparts when specific conditions are present. In a warm and humid environment with no large particles to attract airborne moisture, water vapor can build up to extreme levels, causing relative humidity to spike well beyond 100 percent.
While ultrafine particles are small in size, they can reach large numbers. These particles form many small droplets that quickly and efficiently draw excess water vapor from the atmosphere. This enhanced condensation releases more heat, which makes the updrafts much more powerful. As more warm air is pulled into the clouds, more droplets are launched aloft, producing a runaway effect that results in stronger storms.
"Our findings open a new door to understanding cloud physics, which matters to both weather forecasting and climate modeling," said Li, who has a joint appointment in UMD's Earth System Science Interdisciplinary Center (ESSIC). "In particular, cloud physicists will revisit the mechanisms of aerosol-cloud-precipitation interactions, especially for regions such as the Amazon where the environment has undergone rapid change due to urbanization and deforestation."
This release was adapted from text provided by the Pacific Northwest National Laboratory.
In addition to Li, UMD atmospheric and oceanic science graduate student Yuwei Zhang is a co-author of the research paper and made significant contributions to the computer modeling effort.
The research paper, "Substantial convection and precipitation enhancements by ultrafine aerosol particles," Jiwen Fan, Daniel Rosenfeld, Yuwei Zhang, Scott Giangrande, Zhanqing Li, Luiz Machado, Scot Martin, Yan Yang, Jian Wang, Paulo Artaxo, Henrique Barbosa, Ramon Braga, Jennifer Comstock, Zhe Feng, Wenhua Gao, Helber Gomes, Fan Mei, Christopher Pöhlker, Mira L. Pöhlker, Ulrich Pöschl, and Rodrigo de Souza, was published January 26, 2018 in the journal Science.
This work was supported by the U.S. Department of Energy's Office of Science (Award Nos. DE-AC06-76RLO1830 and DE-SC0012704), the U.S. National Science Foundation (Award No. AGS1534670), the National Science Foundation of China (Award No. 91544217), the European Commission's Project BACCHUS (FP7-603445), the CHUVA project, the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia, Instituto Nacional de Pesquisas da Amazonia, Universidade do Estado do Amazonas, the Fundação de Amparo à Pesquisa do Estado do Amazonas, the Sao Paolo Research Foundation (Award Nos. 2009/15235-8, 2013/05014-0, and 2013/50510-5), the Brazilian National Council for Scientific and Technological Development (Authorization No. 001030/2012-4), the German Federal Ministry of Education and Research (Award No. 01LB1001A), the Brazilian Ministério da Ciência, Tecnologia e Inovação (Award No. 01.11.01248.00), and Secretaria de Estado do Meio Ambiente e Desenvolvimento Sustentável/Centro Estadual de Unidades de Conservação/Reserva de Desenvolvimento Sustentável-Uatumã. The content of this article does not necessarily reflect the views of these organizations.
Media Relations Contact:
University of Maryland
College of Computer, Mathematical, and Natural Sciences
2300 Symons Hall
College Park, MD 20742
About the College of Computer, Mathematical, and Natural Sciences
The College of Computer, Mathematical, and Natural Sciences at the University of Maryland educates more than 9,000 future scientific leaders in its undergraduate and graduate programs each year. The college's 10 departments and more than a dozen interdisciplinary research centers foster scientific discovery with annual sponsored research funding exceeding $175 million.
Matthew Wright | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences