Satellites See Double Jeopardy For Socal Fire Season

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 PHONE 818-354-5011
http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

Sheri Ledbetter 714-289-3143
Chapman University, Orange, Calif.
Sledbett@chapman.edu

News release: 2013-160 May 13, 2013

Satellites See Double Jeopardy For Socal Fire Season

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-160&cid=release_2013-160

PASADENA, Calif. – New insights into two factors that are creating a potentially volatile Southern
California wildfire season come from an ongoing project using NASA and Indian satellite data by
scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif.; and Chapman University, Orange,
Calif.

The scientists tracked the relationship between rainfall and the growth and drying-out of vegetation in
recent months, during an abnormally dry year. They found the timing of rains triggered regional
vegetation growth in January and early February, which then dried out faster than normal during a
period of low rainfall, strong winds and high temperatures in March and April. The combination
likely elevates wildfire risks by increasing available fuel.

The two institutions are combining satellite datasets to monitor moisture changes in vegetation and
soil across Southern California's vast wilderness areas in order to identify early warning signs of
potential wildfires. The scientists are using measurements of soil moisture change from the Indian
Oceansat-2 satellite scatterometer (OSCAT) and of vegetation stress from the Moderate Resolution
Imaging Spectroradiometer (MODIS) sensor on NASA's Aqua satellite.

"The increased soil moisture from the rains, as observed by OSCAT, occurred at an opportune time at
the start of the vegetation growth season," said JPL scientist Son Nghiem, principal investigator of
the project. "This timing enhanced vegetation growth early this year, particularly in Ventura County,
supplying significant new fire fuel, despite one of the driest overall rainfall seasons on record. Had
the rains fallen earlier, when the vegetation was in a dormant state, the effects would have been
minimal." OSCAT measurements provide insight into how much rainwater sinks into the soil to
enhance vegetation growth.

The resulting stress on vegetation and abnormal dry-out, which occurred even before the start of the
dry season, has been seen in measurements by fire agencies at various sampling locations and in
satellite data from MODIS across the Southland, notes Professor Menas C. Kafatos, who leads the
Chapman University team.

Nghiem said the unusual conditions this season underscore the challenge local fire officials face in
tracking how soil moisture changes in response to precipitation and affects the condition of
vegetation. The conditions also highlight the potential for using satellite observations to enhance fire
information and management systems.

The satellite data will support decision-making by wildland fire authorities, including fire
departments in Los Angeles, Ventura and Orange Counties, and the National Oceanic and
Atmospheric Administration's National Weather Service Forecast Office in Oxnard, Calif. While that
office is not responsible for fire management, it supports local fire agencies by issuing fire weather
forecasts, watches and warnings to four California counties, which are home to 11 million people.
The collaboration between scientists and fire agencies will allow them to develop satellite data
products that will be combined with other information to improve the assessment of wildfire danger.

Orange County fire planning specialist George Ewan recently hosted the scientists during a field
excursion in Black Star Canyon, where he demonstrated how he carefully collects snippets of brush
growth and returns them to his laboratory at the Orange County Fire Authority headquarters in Irvine,
Calif., to measure the moisture content of the vegetation.

But collection of plant samples is simply not feasible for all areas of concern across California and
the rest of the United States, Nghiem said. "Mountainous wildlands are difficult to access, and
collecting data manually in them is laborious," he said. "The potential payoff from this satellite
research is significant, both for California's extensive and complex terrain and for the many regions
around the world threatened by wildfires each year."

Kafatos noted that "the combination of satellite observations with live fuel moisture estimates and
calculations from our teamwork is opening new vistas in this important scientific application serving
society."

"The initial results of this effort are very promising examples of putting satellite observations into
practical use for fire management and public benefit," said Lawrence Friedl, director of the NASA
Applied Sciences program in the Earth Science Division at NASA Headquarters in Washington.

The California Institute of Technology in Pasadena manages JPL for NASA.

-end-

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