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Abstract A coronal mass ejection erupted from the Sun on 21 April 2023 and created a G4 geomagnetic storm on 23 April. NASA's global‐scale observations of the limb and disk (GOLD) imager observed bright equatorial ionization anomaly (EIA) crests at ∼25° Mlat, ∼11° poleward from their average locations, computed by averaging the EIA crests during the previous geomagnetic quiet days (18–22 April) between ∼15°W and 5°W Glon. ReversedC‐shape equatorial plasma bubbles (EPBs) were observed reaching ∼±36° Mlat (∼40°N and ∼30°S Glat) with apex altitudes ∼4,000 km and large westward tilts of ∼52°. Using GOLD's observations EPBs zonal motions are derived. It is observed that the EPBs zonal velocities are eastward near the equator and westward at mid‐latitudes. Model‐predicted prompt penetration electric fields indicate that they may have affected the postsunset pre‐reversal enhancement at equatorial latitudes. Zonal ion drifts from a defense meteorological satellite program satellite suggest that westward neutral winds and perturbed westward ion drifts over mid‐latitudes contributed to the observed latitudinal shear in zonal drifts.
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This content will become publicly available on February 1, 2026
Equatorial Ionization Anomaly X‐Pattern Occurrences Observed by the GOLD Mission During Its First 5 Years
Abstract The Global‐scale Observations of Limb and Disk (GOLD) mission has provided an unusual array of upper atmosphere observations from a geostationary platform, including the behavior of the low latitude nighttime ionosphere. One of the features observed by GOLD is the formation of an X‐pattern in the Equatorial Ionization Anomaly when its crests collapse near the magnetic equator. This paper discusses the X‐patterns that were observed during the first 5 years of the GOLD mission (2018–2023). This catalog reveals that X‐pattern occurrences are more frequent during low solar activity, and appear to be driven by changes in the normal low latitude zonal winds. In the longitude region observed by GOLD (approximately 75°W–5°E) they occurred exclusively during the September Equinox‐December Solstice‐March Equinox seasons, and they were more likely to occur near 45°W longitude, near the point where the geomagnetic equator crosses the geographic equator in the western hemisphere.
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- Award ID(s):
- 2152365
- PAR ID:
- 10577848
- Publisher / Repository:
- Wiley Online Library
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Space Physics
- Volume:
- 130
- Issue:
- 2
- ISSN:
- 2169-9380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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