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MODIS Data Product Non-Technical Description - MOD 14

Fire is a force of nature that humans have harnessed to make our lives easier and more productive — by heating our homes, cooking our food, and clearing away obstacles. But though we employ it regularly to our benefit, fire can very easily become a destructive force — through our carelessness and mistakes or via more spontaneous, natural means. Candles left alone can ignite the curtains, backyard brush fires can quickly grow out of control, lightning can ignite forest fires, and hot ash and magma from volcanic eruptions can ignite almost anything they touch.

In addition to the immediate dangers fires present, they also release damaging gases and airborne particles into the atmosphere. These emissions affect ecosystems and atmospheric chemistry near the site of the fire, and can also be transported long distances. For instance, the springtime agricultural fires in Southeast Asia create smoke and gases that get blown across China and far out over the Pacific Ocean. Because fires have such a profound role in the global climate and in peopleĘs everyday lives, and because they are so widespread across the Earth, scientists have turned to satellites for regular observation of global fire patterns. MODIS fire scientists have developed an important new data product called ŠThermal Anomalies, Fires, and Biomass Burning” to take advantage of the fire-detection capabilities of the MODIS sensors on the Aqua and Terra satellites.

MODIS can œsee” fires because fires have a recognizable thermal signature. Whenever the product detects a "hot spot," it flags the signal's location in the data set. When the data get turned into an image, the fire-detection locations from the product are added as an overlay on the image, which marks the fires in bright red. Via the MODIS Rapid Response System, this product made it possible to track large fires such as the Biscuit Complex fire in Oregon and California during July 2002, and the large bushfires in southeastern Australia that burned over two million acres during the first two months of 2003.

Under near-ideal conditions - nadir (straight-down) look with no clouds in the way, not too much smoke, relatively cool background terrain for comparison, etc. - the product can detect fires as small as 50m2. For instance, a small, very hot fire in a cold area, such as an oil-well fire during the winter, would be detectable under the above criteria. But considering that about 70 percent of the planetĘs surface is covered in clouds at any given time, these ideal circumstances are hard to come by. MODIS can routinely detect fires at an average size of 30 meters by 30 meters (900m2) under a variety of conditions: differing satellite positions, all MODIS scan angles, and both relatively hot and cool fires. Under these more typical circumstances, the algorithm can detect a fire about the size of a quarter acre — about a third of the size of an American football playing field. This is quite a feat, considering that at MODISĘ highest resolution, one pixel covers 250 square meters. At this resolution and under the above-stated near-ideal circumstances, MODIS will detect a fire covering only four pixels almost 100% of the time.

A MODIS instrument flies in an orbit 705 kilometers above the Earth Ō thatĘs the about of the distance between Cancun, Mexico, and the Florida Keys, USA Ō and receives data from the entire surface of the Earth every two days. MODIS completes one orbit around the earth every 98 minutes, which makes it well suited for gathering data about time-sensitive events like fires. Add to that the fact that there are two MODIS instruments in orbit, and the differences in fires between morning and afternoon can be detected. This frequent coverage is especially important during fire seasons, when huge wildfires can start in the blink of an eye. Having morning and afternoon looks at the same area also allows scientists to monitor changes in fire frequency, intensity or location over the course of the day.

At institutions like the US Forest Service (USFS), the National Interagency Fire Center (NIFC), and the U.N. Global Fire Monitoring Center, the MODIS Fire Product is routinely used for imagery and maps that aid fire managers in monitoring fires across a large area and allocating resources to regions where they are needed most. These institutions are able to receive MODIS fire data quickly because of the MODIS Rapid Response System, which was designed to automate the computer processing of the fire detection data product and deliver the results to partners in near real time (within 2-4 hours of when MODIS collected the observations). Because of the dynamic nature of fires, and because uncontrolled fires can be very costly, having up-to-date and accurate fire information is very important. In addition to providing this product to various agencies via Rapid Response, results of the product are visible to the general public in much of the MODIS imagery available on this site, in the Visible Earth database, in the Rapid Response gallery, and in the Natural Hazards fire section of the Earth Observatory.

 

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