June 28, 2017

Lightning and Wildfire

Lightning and Wildfire

A new NASA-funded study finds that lightning storms were the main driver of recent massive fire years in Alaska and northern Canada, and that these storms are likely to move farther north with climate warming, potentially altering northern landscapes.

The study, led by Vrije Universiteit Amsterdam and the University of California, Irvine, examined the cause of the fires, which have been increasing in number in recent years. There was a record number of lightning-ignited fires in the Canadian Northwest Territories in 2014 and in Alaska in 2015. The team found increases of between two and five percent a year in the number of lightning-ignited fires since 1975.

To study the fires, the team analyzed data from NASA’s Terra and Aqua satellites and from ground-based lightning networks.

Lead author Sander Veraverbeke of Vrije Universiteit Amsterdam, who conducted the work while at UC Irvine, said that while the drivers of large fire years in the high north are still poorly understood, the observed trends are consistent with climate change.

“We found that it is not just a matter of more burning with higher temperatures. The reality is more complex: higher temperatures also spur more thunderstorms. Lightning from these thunderstorms is what has been igniting many more fires in these recent extreme events,” Veraverbeke said.

Study co-author Brendan Rogers at Woods Hole Research Center in Falmouth, Massachusetts, said these trends are likely to continue. “We expect an increasing number of thunderstorms, and hence fires, across the high latitudes in the coming decades as a result of climate change.” This is confirmed in the study by different climate model outputs.

Study co-author Charles Miller of NASA’s Jet Propulsion Laboratory in Pasadena, California, said while data from the lightning networks were critical to this study, it is challenging to use these data for trend detection because of continuing network upgrades. “A spaceborne sensor that provides high northern latitude lightning data that can be linked with fire dynamics would be a major step forward,” he said.

The researchers found that the fires are creeping farther north, near the transition from boreal forests to Arctic tundra. “In these high-latitude ecosystems, permafrost soils store large amounts of carbon that become vulnerable after fires pass through,” said co-author James Randerson of the University of California, Irvine. “Exposed mineral soils after tundra fires also provide favorable seedbeds for trees migrating north under a warmer climate.”

“Taken together, we discovered a complex feedback loop between climate, lightning, fires, carbon and forests that may quickly alter northern landscapes,” Veraverbeke concluded. “A better understanding of these relationships is critical to better predict future influences from climate on fires, and from fires on climate.”

Explanation from: https://www.nasa.gov/feature/jpl/lightning-sparking-more-boreal-forest-fires/

Coils of Magnetic Field Lines

Coils of Magnetic Field Lines

A smallish solar filament looks like it collapsed into the Sun and set off a minor eruption that hurled plasma into space (June 20, 2017). Then, the disrupted magnetic field immediately began to reorganize itself, hence the bright series of spirals coiling up over that area. The magnetic field lines are made visible in extreme ultraviolet light as charged particles spin along them. Also of interest are the darker, cooler strands of plasma being pulled and twisted at the edge of the Sun just below the active region.

Image Credit: NASA/GSFC/Solar Dynamics Observatory
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21764

The 2XMM J143450.5+033843 Galaxy

The 2XMM J143450.5+033843 Galaxy

Not all galaxies have the luxury of possessing a simple moniker or quirky nickname. The subject of this NASA/ESA Hubble Space Telescope image was one of the unlucky ones, and goes by the rather unpoetic name of 2XMM J143450.5+033843.

Such a name may seem like a random jumble of numbers and letters, but like all galactic epithets it has a distinct meaning. This galaxy, for example, was detected and observed as part of the second X-ray sky survey performed by ESA’s XMM-Newton Observatory. Its celestial coordinates form the rest of the bulky name, following the “J”: a right ascension value of 14h 34m 50.5s (this can be likened to terrestrial longitude), and a declination of +03d 38m 43s (this can be likened to terrestrial latitude). The other fuzzy object in the frame was named in the same way — it is a bright galaxy named 2XMM J143448.3+033749.

2XMM J143450.5+033843 lies nearly 400 million light-years away from Earth. It is a Seyfert galaxy that is dominated by something known as an Active Galactic Nucleus — its core is thought to contain a supermassive black hole that is emitting huge amounts of radiation, pouring energetic X-rays out into the Universe.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1726a/