Comparison of GOLD nighttime measurements of OI 135.6 nm radiance with
the total electron content map: preliminary results
Abstract
The unambiguous 2-dimensional (2D) maps of OI 135.6 nm radiance
retrieved from the Global Observation of Limb and Disk (GOLD) after
sunset are compared with the total electron content (TEC) maps measured
by GPS receivers in the America sector. The OI 135.6 nm radiance
observed by GOLD is an indicator of the peak electron density of the
ionosphere, while the TEC depends on the total electron density in the
column. The comparisons show that both of them are able to capture the
large structures in the equatorial ionization anomaly (EIA) well, and
sometimes they both also capture bubbles. Both show that the ionosphere
after sunset is quite dynamic and has strong day-to-day variability. A
statistical study has also been carried out to check the occurrence rate
of bubbles and the apparent EIA structure between Oct 17, 2018 to May
31, 2019. GOLD is able to image the areas where it is difficult to
situate GPS receivers such as the ocean, while TEC data covers the
full-diurnal cycle. In all, the GOLD and TEC have valuable synergy to
allow us to gain a better understanding of the equatorial ionosphere.