"Improving the role of satellite data in wildfire prediction and monitoring through efforts like these is critical, since traditional field sampling is limited by high costs, and the number and frequency of sites you can sample," said Roberts. "This new data on the relative greenness of a landscape also allows us to see how conditions are changing compared to the past."

The satellite data worked best on landscapes where one plant type was dominant. The amount of vegetation cover in an area and its growth rate also influence the reliability of satellite data for wildfire prediction.

The study also found that in areas where branches and dead foliage often help spread fires, changes in the proportion of green vegetation to other plants may also indicate locations of potential fires, especially after moisture values fall below a critical level. The proportion of greenness determines the manner in which plants absorb and scatter sunlight and plays a major role in moisture retention.

Although scientists have long recognized the importance of moisture conditions in wildfire development, this research suggests that other variables may be just as significant. "While live fuel moisture values are critical in the development of wildfires, it's clearly not the last word. Even if vegetation is extremely dry, there are a number of other factors that influence whether a fire will develop and how quickly it spreads, including the ratio of live to dead foliage, plant type, seasonal precipitation, and weather conditions," said Roberts. "In Southern California, if a strong Santa Ana wind event occurs before our first major rainfall in the fall or winter, the risk for wildfire is significantly heightened."

As researchers continue to better understand wildfire development, they are also creating fire spread computer models that use wind speed and direction forecasts to determi
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Contact: Rob Gutro
robert.J.gutro@nasa.gov
301-286-4044
NASA/Goddard Space Flight Center
20-Dec-2006