Latitudinal Variation of Equatorial Plasma Bubbles Drift Velocities Derived From GOLD Data

Abstract:

NASA’s Global-scale Observations of the Limb and Disk (GOLD) mission observes Earth’s ultraviolet emissions from geostationary orbit. These observations provide a unique opportunity to examine the behavior of Equatorial Plasma Bubbles (EPBs), structures with low plasma density in the nighttime equatorial ionosphere. These observations provide the first simultaneous measurement of EPBs drift velocities at the crests of Equatorial Ionization Anomaly (EIA) and the magnetic equator. We have derived the zonal drift velocity of EPBs over South America using three nights of GOLD data in November 2018. The drift velocities obtained on 27 November 2018 are 116 ± 4, 118 ± 6, and 105 ± 9 m/s at the North and South crests of the EIA and the magnetic equator, respectively. While on 29 November the velocities 107 ± 10, 106 ± 8, and 110 ± 4 m/s agree with the values obtained on 27 th (within the uncertainties), on 28 November the velocities are substantially lower: 80 ± 3, 95 ± 7, and 88 ± 11 m/s. The drift velocities at the EIA crests and the equator are the same within their standard error in these three days of observations during winter solstices. The investigation of EPBs drift velocities at these three locations is expanded to include additional nights during different seasons. Seasonal variations in the drift velocities are compared. Such observation is useful for the predictability of post-sunset ionospheric plasma irregularities.