Nav: Home

Researchers pinpoint promising approach for analyzing atmospheric particles from space

February 07, 2019

WASHINGTON -- A new analysis has revealed that advanced satellite-based instrument capabilities are needed for global monitoring of microscopic particles, or aerosols, in the stratospheric layer of the atmosphere. Aerosols in the stratosphere -- located above approximately 12 kilometers -- increase drastically after a volcanic eruption, leading to changes in the Earth's climate and providing a critical opportunity to test scientific models designed to predict short- and long-term climate variations.

Researchers from NASA Goddard Institute for Space Studies in New York and the National Academy of Sciences in Kyiv, Ukraine, report the new findings in The Optical Society (OSA) journal Optics Express.

When a volcano erupts, large amounts of ash and sulfuric-acid particles can blanket the entire planet, blocking much of the sunlight and temporarily causing global cooling. Scientists are now exploring whether this blanketing effect could be used to counteract global warming by injecting man-made aerosols in the stratosphere. Such geoengineering projects would also require a way to monitor the amount and size of artificial particulates in the stratosphere and the resulting climate effect.

"The global nature of natural and man-made stratospheric aerosols means that a specialized Earth-orbiting instrument is necessary to obtain comprehensive information on their properties and distribution," said Janna Dlugach, a member of the research team from the Ukraine's National Academy of Sciences. "This information is critical for testing climate models and for monitoring climate effects from potential geoengineering projects and major volcanic eruptions, which can affect the livelihood of the entire population."

Monitoring aerosols from space

Over the next decade NASA plans to carry out a specialized mission to monitor aerosols and clouds on Earth. This mission would include an instrument that measures not only the brightness of sunlight reflected by the atmosphere and Earth's surface but also the light's polarization, which carries rich information about the size, composition and amount of aerosol particles.

"The technical characteristics of this future polarimeter are currently the subject of active debate among the scientific community," said Michael Mishchenko, a member of the research team from NASA. "Our paper brings into this discussion the necessity of monitoring not just aerosols in the lower atmosphere, but also stratospheric aerosols that could become a major part of the climate system in the case of a major volcanic eruption or the implementation of a massive geoengineering program."

Measurements of reflected sunlight by orbital instruments are usually dominated by bright water clouds, the land surface and aerosols found in the troposphere -- the atmospheric layer closest to the ground. "This is not problematic when stratospheric aerosols are minimal and thus unimportant relative to tropospheric aerosols," explained Dlugach. "However, it becomes essential to separate out the light coming from stratospheric aerosols in the case of volcanic eruptions or geoengineering activities."

Separating stratospheric aerosols

In the new study, the researchers argue that any future aerosol-monitoring orbital instrument should provide measurements within a narrow spectral channel centered at 1.378 micrometers. "At this wavelength the water vapor in the troposphere can almost completely absorb the sunlight scattered by clouds, terrestrial surfaces and tropospheric aerosols," said Mishchenko. "This enables us to infer the properties of stratospheric aerosols separately from those of tropospheric aerosols."

The researchers used simulated measurements to determine the best way to measure stratospheric aerosols. They began by using a realistic model of stratospheric aerosols to calculate the theoretical brightness and polarization of sunlight that these aerosols would reflect into space. They then added measurement errors that mimic those found in actual satellite data. With the resulting information, they simulated several types of realistic measurements to determine which provides enough information to determine the amount, size and composition of stratospheric aerosols.

"We found that measuring the brightness of light alone does not allow the inference of stratospheric aerosols," said Dlugach. "Our analysis suggests that future aerosol-monitoring space mission should include an instrument that can obtain precise polarization measurements of a terrestrial scene from multiple angles at the 1.378-micrometer wavelength."

The strong water-vapor absorption channel is necessary to cancel out light coming from the lower atmosphere and surface while precise polarization measurements from multiple angles yield detailed information about stratospheric aerosols.

Next, the researchers plan to analyze more challenging observation conditions that would put additional requirements on the instrument design. They also want to determine whether combining polarimetric and lidar observations from the same orbital platform would be beneficial for certain conditions.
-end-
Paper: M. I. Mishchenko, J. M. Dlugach, A. A. Lacis, L. D. Travis, B. Cairns, "Retrieval of volcanic and man-made stratospheric aerosols from orbital polarimetric measurements," Opt. Express, 27, 4, A158-A170 (2019).
DOI: https://doi.org/10.1364/OE.27.00A158

About Optics Express

Optics Express reports on new developments in all fields of optical science and technology every two weeks. The journal provides rapid publication of original, peer-reviewed papers. It is published by The Optical Society and edited by James Leger from the University of Minnesota. Optics Express is an open-access journal and is available at no cost to readers online at: OSA Publishing.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.

Media Contact: mediarelations@osa.org

The Optical Society

Related Volcanic Eruptions Articles:

Oral traditions and volcanic eruptions in Australia
In Australia, the onset of human occupation (about 65,000 years?) and dispersion across the continent are the subjects of intense debate and are critical to understanding global human migration routes.
'Crystal clocks' used to time magma storage before volcanic eruptions
The molten rock that feeds volcanoes can be stored in the Earth's crust for as long as a thousand years, a result which may help with volcanic hazard management and better forecasting of when eruptions might occur.
Super volcanic eruptions interrupt ozone recovery
Strong volcanic eruptions, especially when a super volcano erupts, will have a strong impact on ozone, and might interrupt the ozone recovery processes.
Rare volcanic rocks lift lid on dangers of little-studied eruptions
Unusual rocks discovered on a remote mountainside have alerted scientists to the dangers posed by a little-studied type of volcano.
Revising the history of big, climate-altering volcanic eruptions
Researchers have developed a new isotopic method to analyze the recent history of large stratospheric volcanic eruptions, using 2,600 years' worth of records contained in ice cores from Antarctica. Stratospheric eruptions can launch sulfate particles more than 6 miles above Earth's surface, where they reflect sunlight and temporarily cool the planet.
Smaller, more frequent eruptions affect volcanic flare-ups
Eruption patterns in a New Zealand volcanic system reveal how the movement of magma rising through the crust leads to smaller, more frequent eruptions.
Using artificial intelligence to understand volcanic eruptions from tiny ash
Scientists led by Daigo Shoji from the Earth-Life Science Institute (Tokyo Institute of Technology) have shown that an artificial intelligence program called a Convolutional Neural Network can be trained to categorize volcanic ash particle shapes.
Repeating seismic events offer clues about Costa Rican volcanic eruptions
Repeating seismic events--events that have the same frequency content and waveform shapes--may offer a glimpse at the movement of magma and volcanic gases underneath Turrialba and Poas, two well-known active volcanoes in Costa Rica.
Detecting volcanic eruptions
Geophysicist Robin Matoza leads a case study of an eruption of Calbuco in Chile to evaluate data delivered by infrasound sensors
Mars' oceans formed early, possibly aided by massive volcanic eruptions
A new theory about how oceans and volcanoes interacted during the early history of Mars supports the idea that liquid water was once abundant and may still exist underground.
More Volcanic Eruptions News and Volcanic Eruptions Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at Radiolab.org/donate.