Response of the F2-peak electron density and height to plasma depletion bays in the equatorial nighttime ionosphere observed by FORMOSAT-7/COSMIC-2

FORMOSAT-7/COSMIC-2 (F7/C2) satellite cluster, launched in June 2019, performs radio occultation experiments observing the vertical electron density profiles in the low-latitude ionosphere. The F7/C2 F2-peak electron density (N,,,F2) and height oh,,,F2) are used to identify and examine the behavior of the plasma depletion bay (PDB) structures in the equatorial nighttime ionosphere. The N,,,F2 reveals three distinct PDBs within 60 degrees W-15 degrees E, 30-90 degrees E, and 110-160 degrees E during June solstice, while a single PDB appears within 150-60 degrees W during December solstice. All the four PDBs' features simultaneously appear during March and September equinoxes. Asymmetries in the h,,,F2 over the PDB regions suggests that the electron density increases (decreases) are related to the N,,,F2 ascending (descending) in the summer (winter) hemispheres. Agreements between F7/C2 observations and HWM93 results show that the asymmetry of vertical motions driven by the neutral wind is the main causal mechanism for the longitudinal variation of PDBs. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.