The research appears in the latest issue of the journal Geophysical Research Letters, and will be presented today at the American Geophysical Union conference in San Francisco, Calif.
"We're seeing climate change manifest itself in the upper as well as lower atmosphere," said NCAR scientist Stan Solomon, a co-author of the study. "This shows the far-ranging impacts of greenhouse gas emissions."
Lower density inthe thermosphere, which is the highest layer of the atmosphere, would reduce the drag on satellites in low Earth orbit, allowing them to stay airborne longer. Forecasts of upper-level air density could help NASA and other agencies plan the fuel needs and timing of satellite launches more precisely, potentially saving millions of dollars.
Confirming a prediction
Recent observations by scientists tracking satellite orbits have shown that the thermosphere, which begins about 60 miles above Earth and extends up to 400 miles, is beginning to become less dense, said Robert Kerr, program director in the National Science Foundation's (NSF) Division of Atmospheric Sciences.
This confirms a prediction made in 1989 by Roble and Bob Dickinson at NCAR that the thermosphere will cool and contract because of increasing carbon dioxide levels. The new study is the first to analyze whether the observed change will become more pronounced over the next decade.
At heights of more than 60 miles, one of the main elements of the atmosphere is atomic oxygen, a single atom of oxygen. As carbon dioxide increases near Earth's surface, it gradually diffuses upward and absorbs heat through collisions with atomic oxygen. It then radiates the heat away to space through infrared radiation, and the result is a net cooling of the upper atmosphere. As the molecules cool and settle, the thermosphere loses density.
Also affecting the thermosphere is the 11-year cycle of solar activity. During the active phase of the cycle, ultraviolet light and energetic particles from the sun increase, producing a warming and expansion of the upper atmosphere. When solar activity wanes, the thermosphere settles and cools.
In order to analyze recent solar cycles and peer into the future, the NCAR-PSU team used a computer model of the upper atmosphere that incorporates the solar cycle as well as the gradual increase of carbon dioxide due to human activities. The team also used a prediction for the next solar cycle, issued by NCAR scientist Mausumi Dikpati and colleagues, that calls for a stronger-than-usual solar cycle over the next decade. The model showed a decrease in thermospheric density from 1970 to 2000 of 1.7 percent per decade, or about 5 percent overall, which agrees with observations. The team found that the decrease was about three to four times more rapid during solar minimum than solar maximum.
Impacts on satellites
Many satellites, including the International Space Station and the Hubble Space Telescope, follow a low Earth orbit at altitudes close to 300 miles. Over time, the upper atmosphere drags the satellites closer to Earth. The amount of drag depends on the density of the thermosphere, which is why satellite planners need better predictions of how the thermosphere changes.
"Satellite operators noticed the solar cycle changes in density at the very beginning of the space age," says Solomon. "We are now able to reproduce the changes using the NCAR models and extend them into the next solar cycle."
Cheryl Dybas | EurekAlert!
Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union
UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
24.10.2016 | Power and Electrical Engineering
24.10.2016 | Life Sciences
24.10.2016 | Life Sciences