IEEE - Aerospace and Electronic Systems - February 2022 - 11

Yang et al.
Table 2.
Four Existing Empirical AMD Models Evaluated
Model
Reference
Validated
altitude
Time
Solar drivers
Magnetic drivers
Compositions
MSISE00
JB2008
[14]
0-2500 km
Local time
F10:7
ap
N2; O2; Ar He; O, H, N, and anomalous
oxygen
NEW TESTING MODEL
A new testing model was developed at RMIT with contribution
from the Space Environment Research Centre
(SERC) consortium. It is, like the other models described
thus far, an empirical model that uses a number of variables
as input such as the latitude, longitude, altitude of the
position of interest as well as the year and day of the year.
Fundamentally, the proposed model is composed of two
components-neutral and ion contributions that come
together to give an overall total AMD. The neutrals are
modeled based upon the MSISE90 model outputs while
the ion contribution is based on the International Reference
Ionosphere 2016 (IRI-2016) model, with last update
on January 2, 2016 [38]. Although at lower altitudes the
fraction of mass contributed by ions to the total mass density
is quite low, at 800 km it can reach up to 30% (see
Figure 2), which drives the need for a new model.
MSISE90 IN THE PROPOSED MODEL
To represent the neutral density of the atmosphere, the proposed
model uses the MSIS90 model. This empirical model
is based upon various empirical data. Rather than using the
more recent MSISE00 model, MSISE90 has been chosen due
to its data sources and the aspects that have beenmodeled.
One major difference between the two MSIS models is
the inclusion of satellite drag measurements and satelliteborne
accelerometer data in the MSISE00. These new data
are in addition to the data used for MSISE90 such as incoherent
scatter radar, mass spectrometers, solar UV occultation,
pressure gauges, falling spheres, and detonations [14].
The other major difference mentioned previously is
the new " anomalous oxygen " that is modeled in MSISE00
but not in MSISE90. This " anomalous oxygen " accounts
for nonthermospheric species like Oþ and O to satellite
FEBRUARY 2022
[6]
175-1000 km
Local solar time
F10:7, S10:7, M10:7 and
Y10
Dst and ap
DTM2013
[7]
120-1500 km
Local time
F30
Km
N2; O2; Ar He; O, H, N, N2; O2,He;
O, H
drag at altitudes near the exobase [14], or the altitude of
interest in this article (800 km). As the new testing model
is using the IRI-2016 to account for ionospheric species,
the MSISE90 is a more reasonable choice so that the ion
contribution from MSISE00 does not interfere with
modeling. This ensures that we independently handle the
neutral and ion contributions of the atmosphere.
IRI MODEL
The IRI model is an ionospheric climatology model that
produces monthly averages for various parameters at different
coordinates (latitude, longitude, altitude) and hours
ofthe day [38]. Another aspect affecting ionospheric properties
is solar activity, which can be optionally set in the
Figure 2.
Percentage of ion mass density at an altitude of 800 km, 00:00
universal time and low solar activity. The x-axis indicates the longitude
in degrees, and the y-axis indicates the latitude in degrees.
Different colours indicate the values of ion contributions in total
AMD in percentages.
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