A novel method to identify IMF $B_y$ influence over low-latitude ionosphere from the correlation of magnetic field variations at nearly antipodal stations

This work is directed to explore the efficacy of strong and consistent correlations between the $\mathrm{\Delta }$X component of magnetic field at two equatorial/low-latitude stations at nearly antipodal locations during geomagnetic storms. The antipodal stations considered are Huancayo (HUA: 12.06${}^{\circ }$S, 75.21${}^{\circ }$W geographic; magnetic dip 0.3${}^{\circ }$N) in the Peruvian longitude sector and Alibag (ABG: 18.64${}^{\circ }$N, 72.87${}^{\circ }$E geographic; magnetic dip 10${}^{\circ }$N) in the Indian longitude sector. Six strong geomagnetic storm events during the period 2000-2005, falling in the maximum-to-declining phase of solar cycle 23, are analyzed for this study. These stations are part of the SuperMAG network and data from these stations are openly available. It is noted that although $\mathrm{\Delta }$X variations over these two stations are, in general, uncorrelated, significant correlations are observed on certain occasions. Correlation coefficient of at least 75$\mathrm{\%}$ for 10 minutes is defined as a requisite criterion to infer the possible connection between the $\mathrm{\Delta }$X variations over these two stations. The ionospheric convection maps from the SuperDARN network are also used to understand the Spatio-temporal evolution of the two-cell ionospheric convection patterns over high-latitudes during these periods of observations. This exercise reveals that the $\mathrm{\Delta }$X variations over the antipodal locations are significantly correlated when the two-cell convection maps show appropriate rotations and both the stations possibly come under the single cell. Therefore, this investigation brings out a novel method to identify the IMF $B_y$ influence over the low/equatorial latitudes based on the openly available data.