Mount Hamilton, Calif.
WHEN an electrical storm rolls in, Glenna Roessler of the California Department of Forestry (CDF) can't keep track of all the lightning. Because lightning causes 70 percent of all wildfires in the Western United States, Ms. Roessler uses a large sextant to try to plot the direction and distance of the bolts that singe the area within a 60-mile radius of her lookout tower on Mount Hamilton.
``No way I can catch every lightning strike,'' she says. ``No way!''
Hundreds of bolts struck the Diablo Range during a three-day storm that swept the Bay Area in September last year. CDF crews raced to nearly 250 lightning-caused fires.
Dick Franklin, a fire management specialist, watched the same storm from his Bureau of Land Management (BLM) office in Sacramento, about 100 miles to the northeast. His computer terminal displayed a map of California and northwestern Nevada. Each time lightning struck Mount Hamilton, a small cross appeared on his screen, marking the strike's exact location -- instantly.
The Bureau of Land Management, through its Boise Interagency Fire Center, its California State office, four district offices, and an Automatic Lightning Detection System, can pinpoint the time and location of every lightning bolt that crashes down in an area that includes the 18.6 million acres of California land under BLM management.
This detection system is part of the BLM's Initial Attack Management System (IAMS), a space-age tool now used by the BLM and other federal and state agencies to quicken its response to naturally caused wildfires. (More than 20 fires recently swept across 100,000 acres of southern California, but many of these are suspected of having been set by arsonists.)
The hub of this electronic network, a Data General computer, sits in the BLM office in Boise, Idaho. It connects 29 lightning detectors fanned out over 11 Western states.
These direction finders sense cloud-to-ground lightning strikes. As strikes occur, the computer in Boise records their longitude and latitude, and transmits those coordinates to desktop computer screens in BLM offices across the West.
Each direction finder has an antenna. This antenna distinguishes between various types of radio signals and senses the direction of the flash. With this information, the antenna can spot a bolt of lightning up to 250 miles away. Last year, the five detectors that watch California skies reported nearly 100,000 lightning strikes.
Lightning emits an intense radio signal, with a band-width that stretches across nearly the entire electromagnetic spectrum. The detectors have microprocessors that screen out narrow-band radio signals and calculate the direction of the cloud-to-ground strike.
If another nearby detector does not confirm a strike, the computer ignores the report. When two detectors report the same strike, however, the computer draws an imaginary triangle between the two detectors and the general direction of the lightning strike. The computer then ``triangulates'' the exact location of the strike by using the direction information.
Not only does the detection system quicken federal and state response to lightning-caused fires, it conserves limited firefighting resources.
``Within milliseconds of a lightning strike,'' says Mr. Franklin of BLM's fire and aviation unit, ``we know exactly where to dispatch a reconnaissance aircraft and which agency's plane to send. Before the Automatic Lightning Detection System, the Bureau of Land Management, the California Department of Forestry, the Park Service, and the Forest Service each sent out its own plane.''
The Automatic Lightning Detection System is part of BLM's strategy to collect detailed atmospheric and ground conditions before it dispatches crews to fight a fire. Other parts of the IAMS plan include the following:
Remote Automatic Weather Stations, which gather weather conditions hourly and transmit them once every three hours to the Geostationary Environmental Satellite. The satellite, in turn, relays the information back to ground stations. These solar-powered weather stations report the wind speed, wind direction, relative humidity, air temperature, temperature of potential fuel, and barometric pressure, from hundreds of stations across the West.
The Terrain Data System uses infrared satellite photos from the National Oceanographic and Atmospheric Administration to catalog vegetation types and the contour of the land where a lightning strike could occur. This system reports whether a potential fire could start in a woodland, grassland, or forest, for example, and the slope, elevation, and ``aspect,'' or general appearance, of the land.
IAMS also allows the BLM and other federal and state agencies to rank the severity of wildfires that frequently erupt simultaneously within the state. If lightning strikes occur in several locations at once, the computer can report that one area is more likely to develop into a major burn than others. A fire manager can send a helicopter to a critical site for a more detailed report of the blaze, while waiting to dispatch hand crews, aircraft, or heavy equipment.
``IAMS will be complete when Boise adds a Computer Aided Dispatch program to the system,'' says Franklin. The CAD program will keep track of the Bureau of Land Management's firefighting crews and equipment daily. The California State office will use it to dispatch people and equipment that includes 25 engines, 3 helicopters, 1 Category-I ``Hot Shot Crew,'' 1 overhead team, 20 smoke-jumpers, 1 smoke-jumper aircraft, 15 fire-prevention technicians, and hundreds of firefighters.
The Bureau of Land Management will take delivery on the Computer Aided Dispatch program at the beginning of next fire season.