Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stratospheric accomplice for Santa Ana winds and California wildfires

09.07.2015

Southern Californians and writers love to blame the hot, dry Santa Ana winds for tense, ugly moods, and the winds have long been associated with destructive wildfires.

Now, a new study finds that on occasion, the winds have an accomplice with respect to fires, at least: Natural atmospheric events known as stratospheric intrusions, which bring extremely dry air from the upper atmosphere down to the surface, adding to the fire danger effects of the Santa Anas, and exacerbating some air pollution episodes.


This is a satellite image of the smoke on 2 May 2013, the first day of the Springs Fire northwest of Los Angeles.

Credit: NASA

The findings suggest that forecast models with the capacity to predict stratospheric intrusions may provide valuable lead time for agencies to issue air quality alerts and fire weather warnings, or to reallocate firefighting resources before these extreme events occur.

"The atmosphere could give us an early warning for some wildfires," said Andrew Langford, a research chemist at the National Oceanic and Atmospheric Administration's (NOAA) Earth System Research Laboratory in Boulder, Colorado, and lead author of the study.

Researchers at NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) and the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU-Boulder coauthored the work, which has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The authors took a detailed look at the May 2013 "Springs Fire" that burned 100 square kilometers (25,000 acres) about 75 kilometers (50 miles) northwest of Los Angeles. The researchers used a NOAA forecast model that incorporates satellite observations of ozone, wind data, and other atmospheric information to detect the occurrence of the intrusions.

The analysis showed that in the early hours before the Springs Fire, a tongue of air characteristic of the stratosphere--extremely dry and very high in ozone from the stratosphere's ozone layer--reached to the surface in southern California and extended as far south as Baja California.

The researchers found that ground-based monitoring stations near the fire's origin also confirmed the telltale signs of the intrusion right before the fire broke out: A large drop in relative humidity and a rise in ozone. As the day went on, a combination of factors accelerated the fire: Low humidity, persistent high winds, dry condition of the grasses and other vegetation, clear skies and bright sunlight, and very warm surface temperatures. A few days later, cloudy skies, a drop in temperature, a shift in winds, and widespread rainfall helped extinguish the fire.

The stratospheric intrusion also had another downside during the Springs Fire: It added ozone from the upper atmosphere to the urban and fire-related pollution produced in the lower atmosphere. On the second and third days of the fire, this helped to push levels of ozone--which can harm people's lungs and damage crops--over the federal ozone limit at 24 monitoring sites across southern California. Monitors as far away as Las Vegas also saw a spike in ozone on the third day of the fire. The observed exceedances of the ozone standard were unusual for the region for that time period, suggesting that the stratospheric intrusions were a contributing factor.

"Stratospheric intrusions are double trouble for Southern California," said Langford. "We knew that the intrusions can add to surface ozone pollution. Now we know that they also can contribute to the fire danger, particularly during La Niña years when deep intrusions are more frequent, as recently shown by our NOAA colleagues at the Geophysical Fluid Dynamics Laboratory. The good news is that with models and observations, we can get an early warning from the atmosphere in some cases."

The authors note that stratospheric intrusions have previously been implicated in the explosive development of wildland fires in New Jersey and Michigan, but have not previously been connected to fires in southern California or to the Santa Ana winds. The frequent occurrence of stratospheric intrusions above the west coast during the fall, winter, and spring suggests that similar circumstances may have played a role in other major southern California fires, including the series of destructive fires that burned more than 3,000 square kilometers (more than 800,000 acres) in October of 2003, and burned about 4,000 square kilometers (nearly a million acres) in October of 2007, say the authors.

###

The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 60,000 members in 139 countries. Join the conversation on Facebook, Twitter, YouTube, and our other social media channels.

CIRES is a partnership of NOAA and CU-Boulder.

AGU Contact:
Nanci Bompey
+1 (202) 777-7524
nbompey@agu.org

CIRES Contact:
Katy Human
+1 (303) 735-0196
Kathleen.human@colorado.edu

NOAA Contact:
Monica Allen
+1 (301) 734-1123
Monica.Allen@noaa.gov

Media Contact

Nanci Bompey
nbompey@agu.org
202-777-7524

 @theagu

http://www.agu.org

Nanci Bompey | EurekAlert!

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>