Satellites See Potential Wildfire Threats In SoCal
May 14, 2013

NASA Satellites Detect Double Wildfire Threats In SoCal

April Flowers for - Your Universe Online

An ongoing project using NASA and Indian satellite data has identified two factors that are creating a potentially volatile Southern California wildfire season.

Scientists from NASA´s Jet Propulsion Laboratory (JPL) and Chapman University have tracked the relationship between rainfall and the growth and drying-out of vegetation in recent months, during what has been an abnormally dry year. The data shows that the timing of rains triggered regional vegetation growth in January and February. This growth dried out faster than normal during a subsequent period of low rainfall, strong winds and high temperatures in March and April. This increases the amount of fuel available for wildfires.

In order to identify early warning signs of potential wildfires, the research team is combining satellite data sets to monitor moisture changes in vegetation and soil across Southern California´s vast wilderness areas. Measurements of soil moisture from the Indian Oceansat-2 satellite scatterometer (OSCAT) and measurements of vegetation stress from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA´s Aqua satellite are being used by the research team.

"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. "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."“¯Measurements from OSCAT provide insight into how much rainwater sinks into the soil enhancing vegetation growth.

Professor Menas C. Kafatos, leader of the Chapman University team, notes the resulting stress on vegetation and abnormal dry-out that occurred before the start of the annual dry season has been observed in measurements by fire agencies at sampling locations and in MODIS satellite data across the Southland.

According to the team, the unusual conditions this season highlight the difficulty facing local fire officials in tracking how soil moisture changes in response to precipitation, affecting the condition of the vegetation. The study findings also demonstrate the potential of using satellite observations to enhance fire information and management systems.

Wildland fire authorities, including fire departments in Los Angeles, Ventura and Orange Counties, will use the satellite data to support decision-making in the coming fire seasons, as will the National Oceanic and Atmospheric Administration´s National Weather Service Forecast Office in Oxnard, California. Although that office is not responsible for fire management, it does support local fire agencies by issuing fire weather forecasts, watches and warnings to four California counties, which are home to 11 million people. Collaborations such as these between fire authorities and research scientists will allow the development of satellite data products that can be combined with other information to improve the assessment of wildfire danger.

George Ewan, Orange County fire planning specialist, recently hosted the scientists during a field excursion in Black Star Canyon. Ewan demonstrated his collection process for bringing snippets of brush growth back to his laboratory at the Orange County Fire Authority to measure moisture content of the vegetation.

Plant sample collection, however, is not feasible in all areas of concern across California or the rest of the United States. “¯"Mountainous wildlands are difficult to access, and collecting data manually in them is laborious," Nghiem 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, "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.