Public Release:  Record levels of solar ultraviolet measured in South America

Frontiers

A team of researchers in the U.S. and Germany has measured the highest level of ultraviolet radiation ever recorded on the Earth's surface. The extraordinary UV fluxes, observed in the Bolivian Andes only 1,500 miles from the equator, are far above those normally considered to be harmful to both terrestrial and aquatic life. The results are being published in the open-access journal Frontiers in Environmental Science.

"These record-setting levels were not measured in Antarctica, where ozone holes have been a recurring problem for decades," says team leader Nathalie A. Cabrol of the SETI Institute and NASA Ames Research Center. "This is in the tropics, in an area where there are small towns and villages."

The measurements were made in the southern hemisphere summer of 2003 and 2004, using instruments developed for the European Light Dosimeter Network (Eldonet). They were undertaken as Cabrol's team was investigating high altitude Andean lakes as part of an astrobiology study of Mars-like environments. Dosimeters were deployed on the summit of the towering Licancabur volcano (altitude: 5,917 meters) and at nearby Laguna Blanca (altitude 4,340 meters). The combination of a midday sun near the zenith, as well as the high elevation of these sites, produces higher irradiance levels because of naturally low ozone in such locations. But these intensities of short-wavelength UV-B radiation (280 - 315 nm) are unprecedented.

"A UV index of 11 is considered extreme, and has reached up to 26 in nearby locations in recent years," notes Cabrol. "But on December 29, 2003, we measured an index of 43. If you're at a beach in the U.S., you might experience an index of 8 or 9 during the summer, intense enough to warrant protection. You simply do not want to be outside when the index reaches 30 or 40."

The intense radiation coincided with other circumstances that may have increased the UV flux, including ozone depletion by increased aerosols from both seasonal storms and fires in the area. In addition, a large solar flare occurred just two weeks before the highest UV fluxes were registered. Ultraviolet spikes continued to occur - albeit at lower intensity - throughout the period of solar instability, and stopped thereafter. While the evidence linking the solar event to the record-breaking radiation is only circumstantial, particles from such flares are known to affect atmospheric chemistry and may have increased ozone depletion.

"While these events are not directly tied to climate change, they are sentinels of what could occur if ozone thins globally," Cabrol says. "The thinner and more unstable the ozone, the more prone we will be to this kind of event."

High UV-B exposure negatively affects the entire biosphere, not just humans. It damages DNA, affects photosynthesis, and decreases the viability of eggs and larvae. For these reasons, it is important to keep a close watch on UV flux levels.

"While this unsettling record might be the result of a 'perfect storm' of events, it could happen again," says Cabrol, "because the factors that caused it are not rare. What we need is more monitoring of the ozone changes in these areas. These fluxes, which are comparable to those of early Mars, are occurring in a populated area."

David Black, president and CEO of the SETI Institute, notes that "this is an excellent example of how astrobiology - which includes understanding the atmospheres of other planets - is germane to contemporary concerns here on Earth."

###

Note to editors

Article title: Record Solar UV Irradiance in the Tropical Andes

DOI: 10.3389/fenvs.2014.00019

Journal: Frontiers in Environmental Science

For a copy of the embargoed paper, please contact Gozde Zorlu: press@frontiersin.org

For online articles, please link to the paper which will become freely available at the following: http://journal.frontiersin.org/Journal/10.3389/fenvs.2014.00019/abstract

Gozde Zorlu
Press Contact
Frontiers
E-mail: press@frontiersin.org
Tel: 41 (0)21 510 1712

Nathalie A. Cabrol
Lead Author
SETI Institute
E-mail: nathalie.a.cabrol@nasa.gov
Tel: +1 650 604 0312

David Morrison
Media Contact
SETI Institute
E-mail: dmorrison@seti.org,
Tel: +1 650 336 3171

David Black
President, CEO
SETI Institute
E-mail: dblack@seti.org
Tel: +1 650 960-4510

About the SETI Institute

The SETI Institute is a multi-disciplinary, highly collaborative, research organization whose mission is to explore, understand, and explain the origin, nature and prevalence of life in the universe. Its scientists have expertise in fields ranging from astrophysics and planetary science to biology and social science, as well as computer science and signal detection. The Institute is also committed to sharing knowledge as science ambassadors to the public, the press, and the government. The SETI Institute is a distinguished partner for government agencies, academic institutions, and corporations around the world. For more information, http://www.seti.org 650-961-6633.

About Frontiers

Frontiers is a community-driven open-access publisher and research networking platform. Established by scientists in 2007, Frontiers empowers researchers to advance the way science is peer-reviewed, evaluated, published, communicated, and shared in the digital era. Frontiers drives innovations in peer-review, article level metrics, post publication review, democratic evaluation, research networking and a growing ecosystem of open-science tools. Frontiers joined the Nature Publishing Group family in 2013. The "Frontiers in" journal series has published 20,000 peer-reviewed articles across 45 journals, which receive 6 million monthly views, and are supported by over 140,000 editors, reviewers and authors worldwide. For more information, visit: http://www.frontiersin.org

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.