Mon Dec 15, F. Flechtner
• Sorted by Date • Sorted by Last Name of First Author •
Liu, Mingming, Yuan, Yunbin, Ou, Jikun, and Tan, Bingfeng, 2025. Comparisons of Differential Code Bias (DCB) Estimates and Low-Earth-Orbit (LEO)-Topside Ionosphere Extraction Based on Two Different Topside Ionosphere Processing Methods. Remote Sensing, 17(21):3550, doi:10.3390/rs17213550.
• from the NASA Astrophysics Data System • by the DOI System •
@ARTICLE{2025RemS...17.3550L,
author = {{Liu}, Mingming and {Yuan}, Yunbin and {Ou}, Jikun and {Tan}, Bingfeng},
title = "{Comparisons of Differential Code Bias (DCB) Estimates and Low-Earth-Orbit (LEO)-Topside Ionosphere Extraction Based on Two Different Topside Ionosphere Processing Methods}",
journal = {Remote Sensing},
keywords = {GPS satellite differential code bias (DCB), LEO receiver DCB, LEO-based topside ionosphere vertical electron content (VEC), SH-topside VEC method, EP-topside VEC method, accuracy},
year = 2025,
month = oct,
volume = {17},
number = {21},
eid = {3550},
pages = {3550},
abstract = "{What are the main findings? Using GRACE-A data (400 km in 2016), the
monthly stabilities (STDs) of GPS satellite differential code
biases (DCBs) and low-earth-orbit (LEO) satellites receiver DCBs
using the EP (epoch parameter)-topside vertical electron content
(VEC) method are better than those using the SH (spherical
harmonic)-topside VEC method. For JASON-2 data (1350 km), the
STDs of GPS DCBs using the SH-topside VEC method are slightly
superior to those using the EP-topside VEC method, and LEO DCBs
using the two methods have similar STD results. However, the
root mean square (RMS) results for GPS DCBs using the SH-topside
VEC model relative to the Center for Orbit Determination in
Europe (CODE) products are slightly superior to those using the
EP-topside VEC method. Due to the difference in orbital
altitude, the results and distributions of the GRACE-topside
VECs differ from those of the JASON-topside VECs, with the
former being more consistent with the ground-based results,
indicating that there may be different height structures in the
LEO-topside VECs. Meanwhile, we applied the IRI-GIM
(International Reference Ionosphere model─Global Ionosphere Map)
method to compare the LEO-topside VEC results. The results
indicate that the accuracy of GRACE-A-topside VECs using the EP-
topside VEC method is better than that using the SH-topside VEC
method, whereas for JASON-2, the two methods have similar
accuracy. The temporal and spatial resolutions of the SH-topside
VEC model are higher than those of the EP-topside VEC method,
and the former has a wide range of usability and predictive
characteristics. Using GRACE-A data (400 km in 2016), the
monthly stabilities (STDs) of GPS satellite differential code
biases (DCBs) and low-earth-orbit (LEO) satellites receiver DCBs
using the EP (epoch parameter)-topside vertical electron content
(VEC) method are better than those using the SH (spherical
harmonic)-topside VEC method. For JASON-2 data (1350 km), the
STDs of GPS DCBs using the SH-topside VEC method are slightly
superior to those using the EP-topside VEC method, and LEO DCBs
using the two methods have similar STD results. However, the
root mean square (RMS) results for GPS DCBs using the SH-topside
VEC model relative to the Center for Orbit Determination in
Europe (CODE) products are slightly superior to those using the
EP-topside VEC method. Due to the difference in orbital
altitude, the results and distributions of the GRACE-topside
VECs differ from those of the JASON-topside VECs, with the
former being more consistent with the ground-based results,
indicating that there may be different height structures in the
LEO-topside VECs. Meanwhile, we applied the IRI-GIM
(International Reference Ionosphere model─Global Ionosphere Map)
method to compare the LEO-topside VEC results. The results
indicate that the accuracy of GRACE-A-topside VECs using the EP-
topside VEC method is better than that using the SH-topside VEC
method, whereas for JASON-2, the two methods have similar
accuracy. The temporal and spatial resolutions of the SH-topside
VEC model are higher than those of the EP-topside VEC method,
and the former has a wide range of usability and predictive
characteristics. What is the implication of the main finding? At
present, there is no research to analyze and compare the effects
of the two topside VEC processing methods on DCB estimates and
LEO-topside VEC extraction. It is essential to obtain more
accurate global navigation satellite system (GNSS)/LEO DCBs and
LEO-topside VEC parameters, particularly in future scenarios
with an increase in LEO satellites, which can serve next-
generation GNSS and LEO positioning. For GNSS/LEO DCB estimates,
different evaluation criteria yield different results. The STD
results are related to the heights of LEO receivers, whereas the
RMS results are not. The accuracies of the LEO-topside VEC
results are related to the heights of LEO orbits. Meanwhile, the
temporal and spatial resolutions of the SH-topside VEC model are
higher than those of the EP-topside VECs, and the former have a
wide range of usability and predictive characteristics. At
present, there is no research to analyze and compare the effects
of the two topside VEC processing methods on DCB estimates and
LEO-topside VEC extraction. It is essential to obtain more
accurate global navigation satellite system (GNSS)/LEO DCBs and
LEO-topside VEC parameters, particularly in future scenarios
with an increase in LEO satellites, which can serve next-
generation GNSS and LEO positioning. For GNSS/LEO DCB estimates,
different evaluation criteria yield different results. The STD
results are related to the heights of LEO receivers, whereas the
RMS results are not. The accuracies of the LEO-topside VEC
results are related to the heights of LEO orbits. Meanwhile, the
temporal and spatial resolutions of the SH-topside VEC model are
higher than those of the EP-topside VECs, and the former have a
wide range of usability and predictive characteristics. Global
navigation satellite system (GNSS) differential code bias (DCB)
and topside ionosphere vertical electron content (VEC) can be
estimated using onboard data from low-earth-orbit (LEO)
satellites. These satellites provide the potential to make up
for the lack of ground-based stations in the oceanic and polar
regions and establish a high-precision global ionosphere model.
In order to study the influences of different LEO-topside VEC
processing methods on estimates, we creatively analyzed and
compared the results and accuracy of the DCBs and LEO-topside
VEC estimates using two topside VEC solutions{\textemdash}the
SH-topside VEC (spherical harmonic-topside vertical electron
content) and EP-topside VEC (epoch parameter-topside vertical
electron content) methods. Some conclusions are drawn as
follows. (1) Using GRACE-A data (400 km in 2016), the monthly
stabilities (STDs) of GPS satellite DCBs and LEO receiver DCBs
using the EP-topside VEC method are better than those using the
SH-topside VEC method. For JASON-2 data (1350 km), the STD
results of GPS DCBs using the SH-topside VEC method are slightly
superior to those using the EP-topside VEC method, and LEO DCBs
using the two methods have similar STD results. However, the
root mean square (RMS) results for GPS DCBs using the SH-topside
VEC model relative to the Center for Orbit Determination in
Europe (CODE) products are slightly superior to those using the
EP-topside VEC method. (2) The peak ranges of the actual GRACE-
A-topside VEC results using the SH-topside VEC and EP-topside
VEC methods are within 42 and 35 TECU, respectively, while the
peak ranges of the JASON-2-topside VEC results are both within 6
TECU. Additionally, only the SH-topside VEC model results are
displayed due to the EP-topside VEC method not modeling VEC. Due
to the difference in orbital altitude, the results and
distributions of the GRACE-topside VECs differ from those of the
JASON-topside VECs, with the former being more consistent with
the ground-based results, indicating that there may be different
height structures in the LEO-topside VECs. In addition, we
applied the IRI-GIM (International Reference Ionosphere
model─Global Ionosphere Map) method to compare the LEO-based
topside VEC results, which indicate that the accuracy of GRACE-
A-topside VEC using the EP-topside VEC method is better than
that using the SH-topside VEC method, whereas for JASON-2, the
two methods have similar accuracy. Meanwhile, we note that the
temporal and spatial resolutions of the SH-topside VEC method
are higher than those of the EP-topside VEC method, and the
former has a wide range of usability and predictive
characteristics. The latter seems to correspond to the single-
epoch VEC mean of the former to some extent.}",
doi = {10.3390/rs17213550},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025RemS...17.3550L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
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