Chuck Bednar for redOrbit.com – @BednarChuck
Update: April 8, 2015 8:51AM CST
Since the publication of our original article, we heard from Dr. Daniel Cecil, a member of the Global Hydrology and Climate Center’s lightning team who passed along some cool information about the lightning map, the satellites responsible for the data and related research.
“We use satellites to measure lightning because that allows us to look across large parts of the globe with essentially equal detectability,” Dr. Cecil told redOrbit via email, explaining that the bulk of the observations come from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite, which originally launched in 1997.
TRMM was supposed to be used for just a three-year mission, he noted, but actually went on to have a lifespan of more than 17 years. However, Wednesday April 8 is expected to be its last day of service, as its instruments are scheduled to be shut off in preparation for de-orbiting.
In 2016, the next-generation GOES-R satellite will replace TRMM, and will feature a lightning mapper for continuous observations of lightning. As the satellite’s mission is coming to an end, Dr. Cecil said that he “can’t think of the right words for conveying” how much the satellite has “exceeded our expectations,” and that he believed that its LIS instrument has played a key role in helping scientists better understand differences in thunderstorms all over the world.
“The basic maps show that central Africa has the most lightning in general,” the NASA scientist explained, “[but] digging into the data, we see that thunderstorms occur most often throughout the year there, but individual thunderstorms tend to be stronger (higher flash rates) in subtropical places like northern Argentina, the central US, and Pakistan.”
“In the early days of collecting this data, there was frequent speculation that we would see a trend toward increased lightning due to global warming,” he added. “Of course there has been very little (if any) global warming since then, and no long-term trend in the lightning data. There is a lot of interesting year-to-year variability for different parts of the globe, which seems more important to understand.”
Finally, Dr. Cecil recommended that anyone interested in further investigating the US space agency’s satellite-based lightning climatology program should visit the webpage http://lightning.nsstc.nasa.gov/data/data_lis-otd-climatology.html for “a lot of neat animations for looking at how lightning varies with time of day or day of year, besides the maps of annual-mean flash rate as highlighted recently on the NASA Earth Observatory web page.”
Original: April 6, 2015 11:58AM CST
If you’re trying to avoid lightning strikes (which most of you probably are), make sure you steer clear of land located close to the Equator! A new map compiled by the folks at NASA shows what regions of the world are most likely to experience these sudden electrostatic discharges.
The map was created using data obtained by the Lightning Imaging Sensor (LIS) on NASA’s Tropical Rainfall Measuring Mission satellite from 1998 through 2003, as well as the Optical Transient Detector (OTD) on the OrbView-1/Microlab satellite from 1995 through 2000, the US space agency explained. Flashes above 38 degrees north were based on OTD data only.
Lightning can strike far more than twice in some places
According to Discovery News, the data showed that lightning strikes were more likely to occur on land than in the water because solid earth absorbs sunlight and heats up more quickly than water. As a result, there is stronger convection and greater atmospheric instability on land, which leads to formation of storms capable of producing thunder and lightning.
NASA scientists note that the data also revealed some unusual regional trends. For instance, they observed a high number of flashes in the Brahmaputra Valley of far eastern India during the month of May. This is due to unstable heating and weather patterns that occur just prior to the start of the monsoon, which brings a significant amount of rain but far less lightning.
Central Africa and northwestern South America, on the other hand, tend to have large amounts of lightning throughout the entire year, the agency revealed. The map also indicates that the most lightning flashes occur in the far eastern Democratic Republic of Congo, and Lake Maracaibo in northwestern Venezuela (which reportedly has lightning storms 300 nights per year).
Meet the instruments
TRMM, a research satellite jointly operated by NASA and the Japan Aerospace Exploration Agency, is designed to measure rainfall for weather and climate research purposes. The primary goal of its mission was to enhance understanding of the distribution and variability of precipitation within the tropics as part of the current climate system’s water cycle.
OrbView-1/Microlab, on the other hand, was an imaging satellite designed to collect affordable, high-quality images of the Earth for various purposes. Its OTD instrument counted the number of lightning flashes, measured their intensity, and noted the time and location of occurrence. It was also a prototype for the TRMM’s Lightning Imaging Sensor (LIS) instrument.
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