Researchers detect travelling ionospheric disturbances using giant metrewave radio telescope

Sarvesh Mangla, who has recently completed his PhD from IIT Indore, and his mentor, Prof Abhirup Datta from the IIT’s department of astronomy, astrophysics and space engineering, along with a team, demonstrated how the GMRT significantly advances our understanding of the ionosphere.

Their research paper, “Spectral Analysis of Ionospheric Density Variations Measured With the Large Radio Telescope in the Low-Latitude Region”, was recently published in the international journal Geophysical Research Letters. “Its heightened sensitivity and capabilities allow for more precise measurements and comprehensive investigations of ionospheric fluctuations, ultimately leading to improved technologies and enhanced accuracy in fields like radar and satellite imaging.” said Mangla, who recently joined the National Centre for Radio Astrophysics, and plans to continue this line of research.

The researchers have successfully detected multiple medium-scale TIDs (with a range of 100 to 300 km) and small-scale TIDs (approximately 10 km) at both the observing frequencies of 235 MHz and 610 MHz, according to an official statement from the GMRT.

Prof Yashwant Gupta, director of the National Centre for Radio Astrophysics, said, “This work shows the new capability of the GMRT, bridging the gap between astronomy and earth sciences, by offering a unique perspective on the behaviour of the earth’s ionosphere, while also offering the promise of improving the quality of the radio images made by the GMRT. This kind of result is something we had all along believed to be possible with the GMRT, and I am very pleased this team led by colleagues from IIT Indore has clearly demonstrated this, thereby opening a new window of research with the GMRT.”

According to the official statement, the ionosphere is a part of the upper atmosphere of the earth, lying between 80 and 600 km. It gets its name from the fact that the solar extreme ultraviolet and X-rays ionise the atoms and molecules present at these heights, leading to the formation of a layer that has ions and electrons. Though sitting far above the clouds, the layer plays a surprisingly important role in our daily lives as the electrons and ions leave their mark on the radio waves, including GPS signals.

Disturbances (known as TIDs) occurring in this region can lead to disruptions in radio communications and GPS accuracy. This disturbance in radio waves can also distort the celestial signals gathered by the GMRT. By studying these phenomena, scientists gain insights into how to better manage and mitigate their effects on our communication and navigation systems and also develop insights about correcting the distortions they impose on the GMRT data.

The results of their study also unveiled unexpected changes in the ionosphere during the sunrise hours, along with the observation of significant ionospheric disturbances and smaller-scale structures moving in the same direction. The characteristics of these disturbances are comparable to previous GPS studies conducted at similar geophysical latitudes worldwide.