Abstract:
A self-contained global ionospheric maps
(GIM)-aided Abel retrieval method is adopted that can
account for spherical non-uniformity along the radio wave
path in the vicinity of the radio occultation (RO) region
using the asymmetry factors derived from global background
NmF2 maps. This procedure does not require any
supplementary data sources to augment the Abel retrieval
in order to represent the horizontal gradients in the ionosphere.
This simulation study demonstrates that when
sufficiently dense RO observations are available, the NmF2
values initially derived from classical Abel retrieval (with
the assumption of spherical symmetry) are sufficiently
good and useful to represent the spherical non-uniformities
in electron density distribution. The Ne(h) profiles
retrieved from this Abel retrieval procedure aided with
asymmetry factors provide significant improvement compared
to classical Abel retrieval at both F- and E-regions.
The artificial large-scale structures, such as wave number-3
latitudinal structure and plasma caves underneath the
equatorial ionization anomaly crests, were largely eliminated.
This improved retrieval procedure also reduces the
computational complexity and is suitable when the number
of occultations increased by many times in the future when
FORMOSAT-7/COSMIC-2 (F7/C2) and other RO missions
become operational. The computation simplicity in this self-contained GIM-aided Abel retrieval procedure
enables more accurate retrieval of Ne(h) profiles in near
real time.
