- Why in news
- On 8 July 2026, the Ministry of Science & Technology said Indian Institute of Geomagnetism researchers reconstructed the topside ionosphere over India for the first time, combining ground and space-based data.
- What it is
- The ionosphere is the ionized layer of Earth's upper atmosphere. Its electron density changes with height, time and place, and it affects radio waves and satellite signals. The topside ionosphere is the part above the peak electron density. Models of it often assume a constant scale height.
- Who developed it
- The Indian Institute of Geomagnetism, an autonomous institute of the Department of Science and Technology, developed the method.
- Data combined
- Scale height from COSMIC radio occultation is merged with bottomside ionosonde observations to build the topside electron density profile.
- Gap addressed
- Earlier models assume a constant topside scale height because reliable information on its variation was lacking over India.
- Altitude range
- Electron density up to about 1000 km is needed, as most low Earth orbit satellites operate in this range.
- Why the geomagnetic equator
- Ionospheric dynamics there are highly complex because of the geometry of Earth's magnetic field.
- Impact on navigation
- Ionospheric electron density changes alter signals of satellite navigation systems such as GPS and NavIC.
Don’t confuse with Ionosonde vs COSMIC radio occultation: An ionosonde is a ground radar that probes the bottomside ionosphere. COSMIC radio occultation uses satellite signals bent through the atmosphere to infer electron density profiles.
Don’t confuse with Topside vs bottomside ionosphere: Bottomside lies below the electron density peak and is measured from the ground. Topside lies above the peak and needs satellite data or modelling.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Better regional models improve reliability of satellite communication, GPS and NavIC services.
- Supports space weather prediction, which protects LEO satellites and radio links.
Problems
- Sparse ground instruments and limited satellite coverage restrict data over the equatorial region.
- The study validates 2014 data only, so performance across solar cycles needs testing.
Way forward
- Add more ionosondes and use data from more satellites to test the model across solar conditions.
- Link the model to operational space weather forecasting for NavIC and communication users.
Put in your answer
Indigenous space science: IIG's method shows a DST institute building region-specific space weather capability useful for NavIC.
- 2024Mains GS1 · Q15What aurora borealis and australis are, and how they are triggered.
- 1996Prelims Q36Which atmospheric layer is responsible for deflecting radio waves.
- 1998Prelims Q109Correct upward sequence of atmospheric layers, including ionosphere, from surface.
- 2011Prelims Q27Why ionosphere facilitates radio communication: judge ozone and wavelength statements.
UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Concept-based sci-tech topic (ionosphere, NavIC); science is 17% of Prelims news questions but this is a research result with few testable facts.
Worth revising until Prelims 2028: most news questions come within two years of the event.