Spectral Analysis of ionospheric density variations measured with the large radio telescope in the Low-Latitude region

TL;DR

This paper analyzes ionospheric density variations using spectral analysis of TEC gradient data from the GMRT, revealing wave behaviors and disturbances during sunrise hours in the low-latitude ionosphere.

Contribution

It introduces a spectral analysis method for TEC gradient measurements from GMRT data, identifying wave phenomena and ionospheric changes during sunrise hours.

Findings

Detected medium-scale traveling ionospheric disturbances (MSTIDs)

Observed unanticipated ionospheric changes during sunrise hours

Identified wave propagation direction changes as the sun approaches zenith

Abstract

The low-latitude ionosphere is a dynamic region with a wide range of disturbances in temporal and spatial scales. The Giant Metrewave Radio Telescope (GMRT) situated in the low-latitude region has demonstrated its ability to detect various ionospheric phenomena. It can detect total electron content (TEC) variation with precision of 1 mTECU and also can measure TEC gradient with an accuracy of about $\rm7\times 10^{-4}\,TECU\,km^{-1}$. This paper describes the spectral analysis of previously calculated TEC gradient measurements and validates them by comparing their properties using two bands. The analysis tracked individual waves associated with medium-scale traveling ionospheric disturbances (MSTIDs) and smaller waves down to wavelengths of $\sim$ 10 km. The ionosphere is found to have unanticipated changes during sunrise hours, with waves changed propagation direction as the sun approached the zenith. Equatorial spread\,$F$ disturbances during sunrise hours is observed, along with smaller structures moving in the same direction.