For more than a decade, two NASA science instruments have orbited the planet, observing the flash and fury of Earth’s electrical storms. Now, the lightning information gleaned by these instruments may help NASA scientists and weather forecasters worldwide better understand dangerous weather patterns, and help minimize danger to lives and property.
Lightning researchers at the National Space Science and Technology Center (NSSTC) in Huntsville, Ala., have collated and released 11 years of lightning data from the Optical Transient Detector and the Lightning Imaging Sensor – twin instruments that orbited the planet continuously recording the position, strength and frequency of lightning strikes.
From these two merged data sets, the science team has delivered a unique, comprehensive picture of worldwide lightning activity – one it hopes may yield new insight into the relationship between global climate and weather patterns and the formation and movement of intense and extreme storms.
The lightning information was introduced during the Lightning Imaging Sensor International Workshop, a conclave of international atmospheric scientists held Sept. 11-13 at the National Space Science and Technology Center.
“Delivering this unprecedented wealth of lightning information to the international science community is a major success for NASA and the NSSTC,” said Steve Goodman, a co-investigator in the lightning study. Goodman manages Earth Science research within the Science and Mission Systems Office at NASA’s Marshall Space Flight Center in Huntsville, which jointly operates the NSSTC with a coalition of Alabama research universities.
“Previous lightning studies have relied on just a few years’ worth of data,” Goodman said. “Now we’ve mapped global lightning activity for an entire 11-year solar cycle – the period of rising and falling solar activity that may impact Earth in ways we don’t yet fully understand. We’re eager to have climatologists and weather researchers begin studying this data, looking for trends on a regional and global scale, and identifying storm characteristics that could offer new insight into the relationship between weather and climate.”
The science team is led by principal investigator Hugh Christian of the University of Alabama in Huntsville, located at the NSSTC, and co-investigators Rich Blakeslee and Goodman of the Marshall Center, and Douglas Mach of the University of Alabama in Huntsville. All are atmospheric scientists at the NSSTC, where more than a dozen NASA and university scientists and graduate students support their effort.
Lightning is not difficult to measure from the ground using radio frequency signals, Christian said, but obtaining wide-scale data around the clock is hampered by the limited detection ranges of even the most sophisticated measurement systems. It is especially difficult to accurately track in-cloud and cloud-to-cloud lightning – activity much less visible on the ground than the cloud-to-ground strikes that punctuate heavy thunderstorms.
From space, however, the whole world’s a laboratory. “Satellite tracking provides us the first clear means of obtaining a global lightning picture, including activity during intense oceanic storms, and over remote environments we can’t chart from the ground,” Christian said.
“Global coverage from space expands our understanding of the physical processes that influence the seasonal to interannual variability of storms,” he added. “Over an 11-year period, we can see if and where more intense storms are forming. We can also identify how the lightning flash rate corresponds to standard climate cycles such as El Ni?o, which warms up the Pacific every three to seven years.”
The compilation and delivery of satellite data relies on complex algorithms executed daily by computers at the NSSTC. Researchers there process and analyze raw data to deliver clean, graphical interpretations of lightning strikes, which are geographically mapped to create a three-dimensional global picture. Information collected during every orbit is sent regularly to the National Oceanic and Atmospheric Administration, to help alert the international aviation community of possible storm systems. Academic, commercial and government weather researchers also request the data on a regular basis for various research efforts. Data and products available for download are maintained for public use on an NSSTC Web site.
The Optical Transient Detector and Lightning Imaging Sensor were built and managed for NASA by the Marshall Center. The transient detector was launched to orbit in 1995 as a secondary payload on the Microlab-1 satellite of Orbital Sciences Corp. The imaging sensor was launched in 1997 on the joint Japanese-American Tropical Rainfall Measuring Mission Observatory. Both are essential components of NASA’s Earth Observing System of satellites, and remain vital resources for NASA and university scientists at the NSSTC.
During a 365-day period in 1995-1996, the transient detector alone observed nearly 1 million worldwide lightning flashes. The resulting data have helped NASA scientists determine that lightning strikes around the world at a rate of approximately 45 flashes per second. More than 1.2 billion in-cloud and cloud-to-ground lightning flashes are believed to occur around the world every year, most over continental land masses.
To date, nearly 300 weather and climate researchers in 27 countries have requested lightning data from the two instruments.
Information from the global lightning study, now available, includes merged lightning measurements dating back to May 1995; comparative data from each instrument; grid-based geographic and climatological maps, animations and stills; and full NASA science documentation. DVDs and instrument data are available via the NSSTC Web site:
http://thunder.nsstc.nasa.gov/data.html
For more information about the satellite-based lightning detectors, visit:
For more information about NASA’s Earth Observing Satellites system, visit:
