The American continent is a region that is regularly struck by natural disasters that leave several inhabited areas in cataclysmic ruin. Weather forecast technologies can help save lives by predicting severe weather conditions, but usually with a very small window of warning. However, a satellite lighting detection system developed by Lockheed Martin for Nasa and National Oceanic and Atmospheric Administration (NOAA) could detect storms and tornadoes far in advance.
The company’s Geostationary Lightning Mapper (GLM) is a single-channel, near-infrared optical transient detector that can detect the momentary changes in an optical scene, indicating the presence of lightning. GLM will measure total lightning (in-cloud, cloud-to-cloud and cloud-to-ground) activity continuously over the Americas and adjacent ocean regions with near-uniform spatial resolution of approximately 10km.
The satellite’s primary instrument, the Advanced Baseline Imager, will provide images of earth’s weather every two milliseconds, oceans and environment with 16 different spectral bands, including two visible channels, four near-infrared channels, and 10 infrared channels.
The GLM, on board the Geostationary Operational Environmental Satellite – R Series (GOES-R) spacecraft, was launched by Nasa this month and will be the first operational lightning mapper flown in geostationary orbit.
After it reaches its final designated orbit, GOES-R will be renamed GOES-16. The new satellite will become operational within a year, after undergoing a checkout and validation of its instruments.
Thomas Zurbuchen, associate administrator for Nasa’s science mission directorate in Washington, said: “The launch of GOES-R represents a major step forward in terms of our ability to provide more timely and accurate information that is critical for life-saving weather forecasts and warnings.”
GLM will collect information such as the frequency, location and extent of lightning discharges to identify intensifying thunderstorms and tropical cyclones. These trends could provide critical information to forecasters before these storms produce damaging winds, hail or tornadoes.
Such storms exhibit a significant increase in total lightning activity, often many minutes before the radar detects the potential for severe weather. Used in combination with radar, satellite data from the GOES-R Advanced Baseline Imager instrument, and surface observations, total lightning data from GLM has great potential to increase lead time for severe thunderstorm and tornado warnings and reduce false alarm rates.
Knowledge of total lightning activity and its extent will help improve public safety and save civilian lives. Data from the instrument will also be used to produce a long-term database to track decadal changes in lightning activity. This is important due to lightning’s role in maintaining the electrical balance between Earth and its atmosphere and potential changes in extreme weather and severe storms under a changing climate.
GLM measurements can provide vital information to help the operational weather, aviation, disaster preparation, and fire communities in a number of areas, for example by improved routing of commercial, military, and private aircraft over oceanic regions where observations of thunderstorm intensity are scarce.
Beyond weather forecasting, GOES-R also will be part of the Search and Rescue Satellite Aided Tracking system, an international satellite-based search-and-rescue network operated by NOAA. The satellite is carrying a special transponder that can detect distress signals from emergency beacons.
Dr Hugh Christian from the University of Alabama in Hunsville, who worked on the satellite, stated that one challenge was developing a variable-width pixel to compensate for the curvature of the Earth, so GLM could produce a distortion-free flat image of the western hemisphere.
Several studies have been done in recent times to advance lightning detection technology for more accurate forecasting.
Research commissioned by Nasa and NOAA was conducted by the University of Washington on tracking lightning and using air moisture, temperature and wind speed to give accurate, real-time information.
Robert Holzworth, a professor of earth and space sciences at the university, said: "When you see lots of lightning you know where the convection, or heat-driven upward motion, is the strongest, and that's where the storm is the most intense. Almost all lightning occurs in clouds that have ice, and where there's a strong updraft."
According to their findings, ice particles within clouds separate into lighter and heavier pieces, and this creates charged regions within the cloud. If strong updrafts of wind make the altitude separation big enough, an electric current flows to cancel out the difference in charges.
Researchers at the University of South Florida, a state that is often known as the “lightning capital of the US”, studied the energy of lighting by investigating the ground after a lightning strike rather than during. They deducted the information from several “fossilised” glass tubes that are formed from the energy and heat generated by the strike when current flows through sand, soil or rocks.
Weather forecasts also benefit sectors such as construction, energy and agriculture, where soil preparation, irrigation, sowing, harvesting and crop storage are vulnerable to weather conditions.