USA — NASA data from earth observation satellites is helping build thecapability to determine when and where wildfires may occur by providing detailson plant conditions, according to a recent study.
While information from sophisticated satellites and instruments have recentlyallowed scientists to quickly determine the exact location of wildfires and tomonitor their movement, this geoscience research offers a step toward predictingtheir development and could complement data from National Oceanic andAtmospheric Administration weather satellites used to help calculate firepotential across much of the United States.
By studying shrublands prone to wildfire in southern California, scientistsfound that NASA earth observations accurately detected and mapped two keyfactors: plant moisture and fuel condition – or greenness – defined as theproportion of live to dead plant material. Moisture levels and fuel condition,combined with the weather, play a major role in the ignition, rate of spread,and intensity of wildfires.
“This represents an advance in our ability to predict wildfires usingdata from recently launched instruments,” said lead author Dar Roberts,University of California-Santa Barbara. “We have come a long way in justthe past 5 to 10 years and continue to gather much better data on the variablescritical in wildfire development and spread.”
To find out how well NASA satellites could detect these factors, researchersfirst sampled live fuel moisture, a critical measure for assessing fire danger,from several different plant species in sites across Los Angeles County, Calif.This ground-based data, collected by the Los Angeles County Fire Department overa five year period, were then compared to greenness and moisture measures fromNASA’s Moderate Resolution Imaging Spectrometer and Airborne Visible/InfraredImaging Spectrometer. The space-based data were often closely linked to thefield measurements, suggesting the instruments can be used to determine whenconditions are favorable for wildfires.
“Improving the role of satellite data in wildfire prediction andmonitoring through efforts like these is critical, since traditional fieldsampling is limited by high costs, and the number and frequency of sites you cansample,” said Roberts. “This new data on the relative greenness of alandscape also allows us to see how conditions are changing compared to the past.”
The satellite data worked best on landscapes where one plant type wasdominant. The amount of vegetation cover in an area and its growth rate alsoinfluence the reliability of satellite data for wildfire prediction.
The study also found that in areas where branches and dead foliage often helpspread fires, changes in the proportion of green vegetation to other plants mayalso indicate locations of potential fires, especially after moisture valuesfall below a critical level. The proportion of greenness determines the mannerin which plants absorb and scatter sunlight and plays a major role in moistureretention.
Although scientists have long recognized the importance of moistureconditions in wildfire development, this research suggests that other variablesmay be just as significant. “While live fuel moisture values are criticalin the development of wildfires, it’s clearly not the last word. Even ifvegetation is extremely dry, there are a number of other factors that influencewhether a fire will develop and how quickly it spreads, including the ratio oflive to dead foliage, plant type, seasonal precipitation, and weather conditions,”said Roberts. “In Southern California, if a strong Santa Ana wind eventoccurs before our first major rainfall in the fall or winter, the risk forwildfire is significantly heightened.”
As researchers continue to better understand wildfire development, they arealso creating fire spread computer models that use wind speed and directionforecasts to determine where fires will travel. And in the near future,scientists will likely be able to map fire severity to get an indication of theoverall impact of a wildfire on the landscape and environment, including theamount of carbon dioxide released into the atmosphere. As the data record fromrecent satellites continues to grow, scientists will also be able to bettertrack historical changes that might modify fire danger to provide betterinformation for decision makers.