Model comparisons of equatorial plasma fountain and equatorial anomaly at three locations

Abstract

The equatorial plasma fountain and equatorial anomaly in the ionospheres over Jicamarca (77°W), Trivandrum (77°E), and Fortaleza (38°W) are compared under magnetically quiet (Ap = 4) equinoctial conditions (day 264) at high solar activity (F10.7 = 178). The comparison, carried out using the Sheffield University Plasmasphere-Ionosphere Model with the same perpendicular E×B drift velocity at all locations, is aimed to investigate the modulating effect of neutral wind. The neutral wind is found to produce north-south asymmetries in the plasma fountain and anomaly, with larger plasma flow and stronger anomaly crests occurring in opposite hemispheres at all locations. The north-south asymmetry in the plasma fountain is stronger at locations of larger displacement between the geomagnetic and geographic equators than at locations of larger magnetic declination angle. The vertical E×B drift velocities at the magnetic equators of Trivandrum and Fortaleza are also derived by matching the measured and model values of the peak height hmax. The derived velocities (which correspond to the ionospheric peak) are compared with that measured at Jicamarca using the incoherent scatter radar.