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Lightning to forecast storms – NASA experiment


New Delhi: Humans have always been frightened and fascinated by lightning. This month, NASA is scheduled to launch a new satellite that will provide the first nonstop, high-tech eye on lightning over the North American section of the planet.

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University of Washington researchers have been tracking global lightning from the ground for more than a decade. Lightning is not only about public safety – lightning strike data have recently been introduced into weather prediction, and a new UW study shows ways to apply them in storm forecasts.

“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,” said co-author Robert Holzworth, a UW professor of Earth and space sciences. “Almost all lightning occurs in clouds that have ice, and where there’s a strong updraft.”

On Nov. 19, NASA is scheduled to launch the new GOES-R satellite that will be the first geostationary satellite to include an instrument to continuously watch for lightning pulses. Holzworth will help calibrate the new instrument, which uses brightness to identify lightning, against network data. NASA also funded the recent research as one of the potential applications for lightning observations.

The recent paper, published in the American Meteorological Society’s Journal of Atmospheric and Oceanic Technology, presents a new way to transform lightning strikes into weather-relevant information.

The U.S. National Weather Service has begun to use lightning in its most sophisticated forecasts. This method, however, is more general and could be used in a wide variety of forecasting systems, anywhere in the world. The authors tested their method on two cases: the summer 2012 derecho thunderstorm system that swept across the U.S., and a 2013 tornado that killed several people in the Midwest.

“Using lightning data to modify the air moisture was enough to dramatically improve the short-term forecast for a strong rain, wind and storm event,” said first author Ken Dixon, a former UW graduate student who now works for The Weather Company. His simple method might also improve medium-range forecasts, for more than a few days out, in parts of the world that have little or no ground-level observations.

Apart from ground stations, weather forecasts are heavily dependent on weather satellites for information to start or “initialize” the numerical weather prediction models that are the foundation of modern weather prediction. What’s missing is accurate, real-time information about air moisture content, temperature and wind speed in places where there are no ground stations.

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“We have less skill for thunderstorms than for almost any other meteorological phenomenon,” said co-author Cliff Mass, a UW professor of atmospheric sciences. “This paper shows the promise of lightning information. The results show that lightning data has potential to improve high-resolution forecasts of thunderstorms and convection.”