Spatial asymmetry in topside ion density and vertical E \texttimes B plasma drift velocity within 75\textdegreeE\textendash95\textdegreeE

<p>The ion density measured by the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/ionospherics" title="Learn more about Ionospherics from ScienceDirect\textquoterights AI-generated Topic Pages">Ionospheric</a> Plasma and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/electrodynamics" title="Learn more about Electrodynamics from ScienceDirect\textquoterights AI-generated Topic Pages">Electrodynamics</a> Instrument (IPEI) on board the ROCSAT -1 over the 75\textdegreeE and 95\textdegreeE <a href="https://www.sciencedirect.com/topics/physics-and-astronomy/meridian" title="Learn more about Meridian from ScienceDirect\textquoterights AI-generated Topic Pages">meridian</a> at 600km <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/altitude" title="Learn more about Altitude from ScienceDirect\textquoterights AI-generated Topic Pages">altitude</a> has been utilized to examine the latitudinal and longitudinal distribution within the Indian sector, in particular, the north-south and east-west <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/asymmetry" title="Learn more about Asymmetry from ScienceDirect\textquoterights AI-generated Topic Pages">asymmetries</a> of the equatorial ionization <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/anomaly" title="Learn more about Anomaly from ScienceDirect\textquoterights AI-generated Topic Pages">anomaly</a> (EIA). A <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/longitudinal-gradient" title="Learn more about Longitudinal Gradient from ScienceDirect\textquoterights AI-generated Topic Pages">longitudinal gradient</a> in ion density at 600 km higher towards 95\textdegreeE develops during the noontime and afternoon hours when the EIA is at its peak. The density gradient persists till evening hours when pre-reversal <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/augmentation" title="Learn more about Augmentation from ScienceDirect\textquoterights AI-generated Topic Pages">enhancements</a> occur. The vertical E \texttimes B <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/plasma-drift" title="Learn more about Plasma Drift from ScienceDirect\textquoterights AI-generated Topic Pages">plasma drift</a> <a href="https://www.sciencedirect.com/topics/physics-and-astronomy/velocity" title="Learn more about Velocity from ScienceDirect\textquoterights AI-generated Topic Pages">velocity</a> measured simultaneously by ROCSAT -1 for the same space-time configuration has also been studied. In addition to <a href="https://www.sciencedirect.com/topics/physics-and-astronomy/ocean-tides" title="Learn more about Ocean Tides from ScienceDirect\textquoterights AI-generated Topic Pages">diurnal</a>, seasonal and solar activity variations in E \texttimes B drift velocity, the longitudinal gradient is also observed. The EIA at the altitude of 600 km peaks at different latitudes and are mostly asymmetric about the magnetic <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/equator" title="Learn more about Equator from ScienceDirect\textquoterights AI-generated Topic Pages">equator</a>. From midnight till 0800 LT, the ion density across the equator is nearly uniform in the equinoxes. But in the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/solstice" title="Learn more about Solstice from ScienceDirect\textquoterights AI-generated Topic Pages">solstices</a>, the density exhibits a north-south gradient. In the June solstice, density is higher in the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/northern-hemisphere" title="Learn more about Northern Hemisphere from ScienceDirect\textquoterights AI-generated Topic Pages">northern hemisphere</a> and decreases gradually towards south. The gradient in density reverses in December solstice. Normally, the EIA peaks within 1200 LT and 1600 LT while around 2000 LT, pre-reversal enhancement of ionization occurs affecting the EIA evening structure. The strength of the EIA also exhibits seasonal, year-to-year and hemispheric variations. The longitudinal asymmetry of drift velocity along 75\textdegreeE and 95\textdegreeE <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/longitude" title="Learn more about Longitude from ScienceDirect\textquoterights AI-generated Topic Pages">longitude</a> sectors is the contributing factor behind the observed longitudinal asymmetry in ion density. Significant positive correlation between the strength of the EIA and E \texttimes B drift is observed in both longitudes.</p>