Wennberg Lab Shows How Wildfire Smoke Increases Ozone Pollution
12-09-21
Using data gathered from a specially equipped jet that spent a month flying through and studying wildfire plumes, scientists have a better understanding now of how wildfire smoke impacts air quality. "Of course it is well known that wildfires lower air quality. But it's important to understand the chemical and physical mechanisms by which they do so that we can more effectively forecast how individual fires will impact the communities downwind of them," says Paul O. Wennberg, R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering; Executive Officer for Environmental Science and Engineering; Director, Ronald and Maxine Linde Center for Global Environmental Science. [Caltech story]
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Paul Wennberg
Lu Xu
Soil Moisture Drives Year-to-Year Change in Land Carbon Uptake
04-01-21
Earth's land ecosystems absorb a large portion of all the carbon dioxide emissions produced by human activities, helping to slow global warming. On average for a given year, plants and soil take up, or fix, about 30 percent of human emissions. But from one year to the next, that number can be as high as 40 percent or as low as 20 percent. Climate scientists aim to pin down exactly what produces this variability so they can account for it and create the most accurate models for predicting future climate. "Our results show that soil moisture significantly impacts near-surface temperatures and atmospheric humidity because of these land–atmosphere feedbacks," says Christian Frankenberg, Professor of Environmental Science and Engineering; Jet Propulsion Laboratory Research Scientist. [Caltech story]
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Christian Frankenberg
postdocs
Vincent Humphrey
Solar Geoengineering May Not be a Long-Term Solution for Climate Change
11-23-20
Pumping aerosols into the atmosphere to reflect sunlight, thus cooling Earth, is one last-ditch method for dealing with climate change. According to new research, solar geoengineering may fail to prevent catastrophic warming in the long run. It would not prevent high atmospheric carbon dioxide concentrations from destabilizing low-lying clouds, opening the door to extreme warming. "Solar geoengineering ultimately may not fix the problem if high greenhouse gas emissions continue for more than a century," says Tapio Schneider, Theodore Y. Wu Professor of Environmental Science and Engineering; Jet Propulsion Laboratory Senior Research Scientist. [Caltech story]
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Tapio Schneider
Undersea Earthquakes Shake Up Climate Science
09-19-20
Researchers show how they are able to make use of existing seismic monitoring equipment, as well as historic seismic data, to determine how much the temperature of the earth's oceans has changed and continues changing, even at depths that are normally out of the reach of conventional tools. They do this by listening for the sounds from the many earthquakes that regularly occur under the ocean, says Jörn Callies, Assistant Professor of Environmental Science and Engineering. Callies says these earthquake sounds are powerful and travel long distances through the ocean without significantly weakening, which makes them easy to monitor. [Caltech story]
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Jörn Callies
New Climate Model to Be Built from the Ground Up
12-13-18
"Projections with current climate models—for example, of how features such as rainfall extremes will change—still have large uncertainties, and the uncertainties are poorly quantified," says Professor Tapio Schneider, principal investigator of the Climate Modeling Alliance (CliMA). "For cities planning their stormwater management infrastructure to withstand the next 100 years' worth of floods, this is a serious issue; concrete answers about the likely range of climate outcomes are key for planning." The new climate model will be built by a consortium of researchers led by Caltech, in partnership with MIT; the Naval Postgraduate School (NPS); and JPL, which Caltech manages for NASA. It will use data-assimilation and machine-learning tools to improve itself in real time, harnessing both Earth observations and the nested high-resolution simulations. "The success of computational weather forecasting demonstrates the power of using data to improve the accuracy of computer models; we aim to bring the same successes to climate prediction," says Professor Andrew Stuart. [Caltech story]
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ESE
Tapio Schneider
Andrew Stuart
Scientists Discover Unexpected Side Effect to Cleaning Up Urban Air
12-19-17
For decades, efforts to reduce air pollution have led to cleaner air in U.S cities like Los Angeles, with subsequent improvements in public health. Those efforts have targeted both nitric oxides and hydrocarbons. Hydrocarbons are emitted from many sources including gasoline-powered cars, trucks, solvents, cleaners used both at home and in industrial settings, and even trees. Professor Paul O. Wennberg and colleagues have found that there is another chemical pathway for forming organic hydroperoxides—one that occurs at nitric oxide levels substantially higher than can be found in the atmosphere over unpopulated regions. "This is chemistry that does not exist in any of the models of how nitric oxide and hydrocarbons interact," says Professor Wennberg. [Caltech story]
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Paul Wennberg
