edu.ucar.opensky::articles:25914 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T20:00:45.550437 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7tx3k76 https://doi.org/10.5065/wb42-vp18 https Related Dataset #1 Data for WACCMX EIA Hemispherically asymmetric evolution of nighttime ionospheric equatorial ionization anomaly in the American Longitude Sector 2022-11-01T00:00:00Z publication https://n2t.org/ark:/85065/d7tx3k76 https://doi.org/10.1029/2022JA030706 Cai, X. author Qian, Liying author Wang, Wenbin author McInerney, Joseph author Liu, Hanli author Eastes, R. W. author UCAR/NCAR - Library publisher The Global-scale Observation of Limb and Disk (GOLD) mission observed distinct post-sunset, hemispherically asymmetric evolution of the equatorial ionization anomaly between 40 degrees and 50 degrees W on 19 November 2018, with the southern crest shifting poleward but the northern crest remaining in the same latitude region. The Whole Atmosphere Community Climate Model-eXtended captured this phenomenon. Diagnostic analysis revealed that this asymmetric evolution was due to the hemispheric asymmetry in plasma transport by E x B drifts and neutral winds. In the Northern hemisphere, northward neutral wind transport dominated around sunset (20 UT near 45 degrees W), causing the crest to be at lower altitudes and decay faster. After pre-reversal enhancement (PRE) occurred at 20 UT in the northern hemisphere, E x B and neutral wind transport largely balanced each other, and the crest remained in the same latitude region. In the southern hemisphere EIA crest, PRE occurred around 1 hr later than the one in the north. The northward neutral wind transported the plasma to higher altitudes with less recombination. E x B transport augmented the neutral wind transport after 21 UT, lifting and pushing the crest poleward. The magnetic field configuration (large declination) and the resultant occurrence time difference in PRE between 40 degrees W and 50 degrees W not only play critical roles in the asymmetric evolution of the two crests, but also makes it possible for this phenomenon to be observed in the GOLD field-of-view. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2022 American Geophysical Union. None eng geoscientificInformation