A brand new auroral phenomenon found by Finnish researchers a 12 months in the past might be brought on by areas of elevated oxygen atom density occurring in an atmospheric wave channel. The speculative rationalization supplied by the researchers gained help from a brand new examine.
Observations made by University of Helsinki researchers elevated the validity of a speculative mechanism in response to which a sort of aurora borealis named ‘dunes’ is born. In the brand new examine, pictures of the phenomenon taken by an worldwide group of hobbyists in Finland, Norway and Scotland have been in comparison with concurrent satellite tv for pc information.
The uncommon kind of aurora borealis was seen within the sky on 20 January 2016 and recorded in images taken by a number of hobbyists.
“The dunes were seen for almost four hours in a very extensive area, with the pattern extending roughly 1,500 kilometers from east to west and some 400 kilometers from north to south,” says Postdoctoral Researcher Maxime Grandin from the Centre of Excellence in Research of Sustainable Space coordinated by the University of Helsinki.
Useful photographic and video materials was collected in shut cooperation with Finnish aurora borealis hobbyists, using each the web and social media. Among different issues, a time lapse video shot on the night time in query by a Scottish hobbyist was discovered. The video was used to estimate the dunes’ propagation pace at over 200 m/s.
The examine was revealed within the esteemed AGU Advances journal.
Validity of the wave information principle confirmed
Northern Lights are born when charged particles ejected by the Sun, corresponding to electrons, collide with oxygen atoms and nitrogen molecules in Earth’s environment. The collision momentarily excites the atmospheric species, and this excitation is launched within the type of mild.
New sorts of aurora borealis are not often found. The identification of this new auroral type final 12 months was the end result of an distinctive collaboration between hobbyists who offered observations and researchers who began wanting into the matter.
The new auroral type named dunes is comparatively uncommon, and its presumed origin is peculiar.
“The differences in brightness within the dune waves appear to be caused by the increased density of atmospheric oxygen atoms,” says Professor Minna Palmroth.
A 12 months in the past, researchers on the Centre of Excellence in Research of Sustainable Space concluded that the dune-like form of the brand new auroral emission kind could possibly be brought on by concentrations of atmospheric oxygen. This elevated density of oxygen atoms is assumed to be led to by an atmospheric wave often called a mesospheric bore touring horizontally inside a wave information established within the higher environment.
This uncommon wave information is created in between the boundary of the atmospheric layer often called the mesosphere, which known as the mesopause, and an inversion layer that’s intermittently shaped under the mesopause. This permits waves of a sure wavelength to journey lengthy distances by the channel with out subsiding.
The electron precipitation and temperature observations made within the just lately revealed examine supported the interpretations of the dunes’ origins made a 12 months earlier. An impartial commentary was made of the wave channel showing within the space of the dunes, however there aren’t any commentary information for the mesospheric bore itself but.
“Next, we will be looking for observations of the mesospheric bore in the wave guide,” Maxime Grandin says.
According to the commentary information, electron precipitation occurred within the space the place the dunes appeared on 20 January 2016. Therefore, it’s extremely doubtless that electrons having the suitable vitality to result in auroral emissions at an altitude of roughly 100 kilometers have been concerned. The observations have been collected by the SSUSI instrument carried by a DMSP satellite tv for pc, which measures, amongst different issues, electron precipitation.
On the night time in query, there was an exceptionally sturdy temperature inversion layer within the mesosphere, or a barrier generated by layers of air with totally different temperatures. The inversion layer related to the origins of the wave channel was measured with the SABER instrument carried by the TIMED satellite tv for pc. The commentary helps the speculation in response to which the auroral type originates in areas of elevated oxygen density occurring within the higher environment wave information.
Citizen scientists uncover a brand new type of the Northern Lights
Maxime Grandin et al, Large‐Scale Dune Aurora Event Investigation Combining Citizen Scientists’ Photographs and Spacecraft Observations, AGU Advances (2021). DOI: 10.1029/2020AV000338
Confirmation of an auroral phenomenon (2021, May 4)
retrieved 4 May 2021
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