Above: MODIS active fire data that shows fire activity from 2000-2015 for 1km pixels. Nicole M. Vaillant, Crystal A. Kolden, Alistair M. S. Smith.
On May 1 we published a map produced by FEMA with data about the number of wildfires by county in the United States that were larger than 300 acres between 1994 and 2013. As some of our readers pointed out the information apparently came from official fire reports filed by various jurisdictions, which does not guarantee that every wildfire is represented in the data.
After seeing the map, Krystal A. Kolden, a pyrogeographer and Associate Professor of Forest, Rangeland, and Fire Sciences at the University of Idaho sent us the above map. She said:
As an alternative, we created a map from MODIS [satellite] active fire data that shows fire activity from 2000-2015 for 1km pixels, so it’s normalized by area. This was published in the journal Current Forestry Reports last year.
The satellite data fills in some of the blank spots in the FEMA map, showing heat from all types of vegetation fires especially in the plains states where it’s not uncommon for a volunteer or rural fire department to suppress a 1,000-acre grass fire and then go on about their business — without completing a report. It also shows much more activity in the lower Mississippi River Valley and the Flint Hills of Oklahoma and Kansas where a great deal of prescribed fire and agricultural burning occurs.
But the MODIS satellite data is not perfect either. MODIS stands for MODerate Resolution Imaging Spectroradiometer on board NASA’s polar orbiting Earth Observing System Terra and Aqua satellites. The orbit of the Terra satellite goes from north to south across the equator in the morning and Aqua passes south to north over the equator in the afternoon resulting in global coverage every 1 to 2 days. Fires in light fuels, such as grass, can ignite, burn thousands of acres, and go out or be suppressed before the next overflight. Or, the fire might not be completely out but a large acreage of burned vegetation can cool and not be detected by the heat-detecting satellite flying hundreds of miles overhead.
This could change, however, when the new GOES-16 satellite becomes fully operational since it has much better resolution and is in geostationary orbit rescanning an area as often as every 30 seconds.
Dr. Kolden said, “The improved temporal resolution of GOES-16 may be a game changer for trying to quantify energy released from biomass burning, and to better understand how fire intensity is related to weather and climate.”
