Study of Aerosols Stands to Improve Climate Models

Friday, August 8, 2014

Study of Aerosols Stands to Improve Climate Models

Study of Aerosols Stands to Improve Climate Models:

Low-level clouds along the California coast are visible in this July 26, 2014 image from the NOAA/NASA Geostationary Operational Environmental Satellite (GOES)-15 satellite. A new NASA/Caltech study examines how changes in aerosol levels affect this key type of cloud that helps cool our planet.
Credit: NASA-Goddard Space Flight Center, data from NOAA GOES

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August 05, 2014

Of all the factors that influence Earth's changing climate, the effect that tiny particles in Earth's atmosphere called aerosols have on clouds is the least well understood. Aerosols scatter and absorb incoming sunlight and affect the formation and properties of clouds. Among all cloud types, low-level clouds over the ocean, which cover about one-third of the ocean's surface, have the biggest impact on the albedo, or reflectivity, of Earth's surface, reflecting solar energy back to space and cooling our planet.

Now a new, comprehensive global analysis of satellite data led by Yi-Chun Chen, a postdoctoral fellow at NASA's Jet Propulsion Laboratory, Pasadena, California, and a joint team of researchers from JPL and the California Institute of Technology in Pasadena, has quantified how changes in aerosol levels affect these warm clouds over the ocean. The findings appeared Aug. 3 in the advance online version of the journal Nature Geoscience.

Changes in aerosol levels have two main effects -- they alter the amount of clouds in the atmosphere and change their properties. Water vapor condenses on aerosol particles into cloud droplets or cloud ice particles, so higher levels of aerosols mean more clouds. With regard to cloud properties, increased aerosol levels can either increase or decrease the amount of liquid water in clouds, depending on whether the clouds are raining or not, the stability of the atmosphere and humidity levels in the upper troposphere. The team analyzed 7.3 million individual data points from multiple satellites in the international constellation of Earth observing satellites known as the Afternoon Constellation, or A-Train, from August 2006 to April 2011 to provide the first real estimate of both effects.

The researchers found each effect to be of similar magnitude - that is, changing the amount of the clouds and changing their internal properties are both equally important in their contribution to cooling our planet. Moreover, they found that the total impact from the influence of aerosols on this type of cloud is almost double that estimated in the latest report of the United Nations' Intergovernmental Panel on Climate Change.

"These results offer unique guidance on how warm cloud processes should be incorporated in climate models with changing aerosol levels," said John Seinfeld, the Louis E. Nohl professor and professor of chemical engineering at Caltech.

The study is funded by NASA and the Office of Naval Research.

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information, visit:

http://www.caltech.edu/content/study-aerosols-stands-improve-climate-models

For more information about NASA's Earth science activities in 2014, visit:

http://www.nasa.gov/earthrightnow

Alan Buis

818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

Alan.Buis@jpl.nasa.gov

Kimm Fesenmaier

626-395-6240

Caltech, Pasadena, Calif.

kfesenma@caltech.edu

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

UFO SIGHTINGS PHOTO PHOTOGRAPHY

The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

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UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).

Photos of Nature | Nature Photography What is The Universe

Photos of Nature | Nature Photography What is The Universe

Friday, August 8, 2014