Vol.:(0123456789) Acta Geodaetica et Geophysica https://doi.org/10.1007/s40328-020-00290-9 1 3 ORIGINAL STUDY Ionospheric anomaly detection and Indian ionospheric climatology from GAGAN receivers K. M. Sridhar 1  · M. Sridhar 1  · Swapna Raghunath 2  · D. Venkata Ratnam 1 Received: 5 July 2019 / Accepted: 10 February 2020 © Akadémiai Kiadó 2020 Abstract The ionospheric anomalies are often responsible for compromising the accuracy and per- formance of Global Navigation Satellite System (GNSS). GPS Aided Geo Augmented Navigation (GAGAN) is the autonomous Space Based Augmentation System of India which serves to provide timely error detection and correction for the corrupted GNSS sig- nals in aircrafts. This paper discusses a Maximum Minimum Eigen (MME) detector to identify the ionosphere induced errors in the GNSS signals. Data has been collected from 24 diferent GAGAN receivers spread over the length and breadth of India from January to December, 2015. The climatology of ionospheric anomaly over India, has been established using the MME detector. This paper discusses the spatio-temporal dependence of iono- spheric anomalies over India. The observations indicate an increased ionospheric activity in the course of equinoxes and a comparitively quiet ionosphere in the course of solstices. A higher number of ionospheric disturbance incidents have been noticed closer to the anomaly crest. The results from the MME detector have been verifed against the Rate of Total Electron Content (TEC) Index (ROTI) values and S4 observations for the year 2015 at the 24 GAGAN TEC stations. The disturbance climatology obtained from MME detec- tor, ROTI and S4 exhibit a high correlation. However, the outcome of the MME detector clearly shows that it is capable of picking up even small irregularities in the ionospheric TEC. Keywords GAGAN · ROTI · Maximum minimum eigen detector · Ionosphere · GNSS * D. Venkata Ratnam dvratnam@kluniversity.in K. M. Sridhar karnammsridhar@gmail.com M. Sridhar sridhar.m@kluniversity.in Swapna Raghunath swapna.karnam1@gmail.com 1 Department of ECE, Koneru Lakshmaiah Education Foundation, Guntur, Andhra Pradesh, India 2 Department of ECE, G Narayanamma Institute of Technology and Science, Hyderabad, Telangana, India