Impact of 15 Jan 2010 annular solar eclipse on the equatorial and low latitude ionosphere over Indian region from Magnetometer, Ionosonde and GPS observations

TL;DR

This study investigates the effects of the Jan 15, 2010 annular solar eclipse on the Indian equatorial and low-latitude ionosphere using magnetometer, ionosonde, and GPS data, revealing significant electric field changes and ionospheric modifications.

Contribution

It provides detailed observational evidence of electric field reversal and ionospheric responses during the eclipse, highlighting electrodynamical effects over mere photo-ionization depletion.

Findings

Electric field at the equator was flipped for several hours.

Reduced Equatorial Ionization Anomaly (EIA) observed during eclipse.

Enhanced F-region peak despite reduced VTEC.

Abstract

The annular eclipse of Jan 15, 2010 over southern India was studied with a network of multi-instrumental observations consisting magnetometer, ionosonde and GPS receivers. By selecting the day before and the normal EEJ days as the control days, it is intrinsically proved that the regular eastward electric field for the whole day at the equator was not just weakened but actually was flipped for several hours by the influence of tides related to the spectacular Sun-Moon-Earth alignment near the middle of the day. The effect of flipping the electric field was clearly seen in the equatorial ionosonde data and through the large array of GPS receivers that accomplished the TEC data. The main impact of the change in the electric field was the reduced EIA at all latitudes, with the anomaly crest that shifted towards the equator. The equatorial F-region density profile was also showing an enhanced F region peak in spite of a reduced VTEC. By comparison to the plasma density depletion associated with the temporary lack of photo-ionization during the episode of eclipse, the electrodynamical consequences of the eclipse were far more important and influenced the plasma density over a wide range of latitudes.