Aurora-like fragments: From fascinating discovery to understanding 

Popular Science Description 

A strange new type of northern lights has been discovered in the High Arctic above Svalbard. These small splinters of green light were seen forming chains close to auroral arcs and were named fragmented aurora-like emissions – or simply ‘fragments’. We want to figure out what causes fragments and if they are part of a bigger system that is connected to the nearby aurora. 

 Researching fragments will allow us to shine a light on types of turbulence high in the atmosphere that are invisible, so are usually difficult to measure. It is important to understand turbulence because it can disturb communication and navigation systems and might also suggest that energy is flowing down and heating the atmosphere, which can cause the atmosphere to expand and slow down orbiting satellites. 

Fragments are not aurora in the normal sense since they are not caused by particles from space crashing into the Earth’s atmosphere. We therefore put them into the category of ‘aurora-like’. In 2016, citizen scientists discovered a different aurora-like feature, which they named STEVE. Next to STEVE, small green ‘streaks’ sometimes appear that resemble fragments but at much lower latitudes. We will compare fragments and streaks to investigate if the same turbulence is happening in different locations and how different aurora and aurora-like systems are connected. 

To carry out the project, we will use different types of cameras to find fragments and streaks. We will also use a new cutting-edge radar system that will soon start operating called EISCAT 3D, which will allow us to measure the environment in and around the fragments in the highest detail in 3-dimensions so far possible with today’s technology. We will also team up with citizen scientists in Svalbard and internationally to gather more data and communicate our research to the public. 

Photos: Fragments (left) Sophie Cordon, Streaks (right) Donna Lach  

Summary

The ionosphere is a region rich in plasma instabilities that create structures on many different scales. This project seeks to understand the cause of exciting new aurora-like features called fragments that were discovered above Svalbard in 2021. The fragments are ‘aurora-like’ because they are not caused by particle precipitation and therefore cannot be called aurora in the traditional sense. Their cause is currently a mystery, but an important one to solve as they are a visible manifestation of usually invisible instabilities that occur when plasma in the ionosphere is accelerated due to strong electric fields. The fragments show structuring on multiple scale sizes, which could mean that multiple instabilities act together to form them. They also appear next to classical auroral structures, which means there could be local coupling between aurora and aurora-like structures. To study these small scale structures and their larger scale systems and ionospheric background conditions requires both optical measurements and radar measurements capable of resolving small structures that change rapidly. We will use the state of the art new EISCAT 3D radar to measure the fragments in high resolution. We will also try to measure a different aurora-like structure called ‘streaks’, which are similar to fragments but are a part of a different system of aurora and aurora-like features. By combining EISCAT 3D and other radar and optical measurements, we will uncover which instabilities generate fragments and streaks. We will make new models using the EISCAT 3D data to reveal the systems that link aurora and aurora-like features together. This work is important as the systems the fragments and the streaks are a part of could heat and expand the neutral atmosphere, causing drag on satellites. The turbulence can also cause drop outs in GPS and radio signals. This project will help us understand the behaviour of the fragment and streak systems and mitigate the challenges they pose.