Articles | Volume 38, issue 5
https://doi.org/10.5194/angeo-38-969-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/angeo-38-969-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
10 Sep 2020
Regular paper |
| 10 Sep 2020
| 10 Sep 2020
The very low-frequency transmitter radio wave anomalies related to the 2010 Ms 7.1 Yushu earthquake observed by the DEMETER satellite and the possible mechanism
Shufan Zhao
CORRESPONDING AUTHOR
National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
XuHui Shen
National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
Zeren Zhima
National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
Chen Zhou
Electronic Information School, Wuhan University, Wuhan, 430072,
China
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Subject: Earth's ionosphere & aeronomy | Keywords: Modelling and forecasting
Modeling total electron content derived from radio occultation measurements by COSMIC satellites over the African region
Analysis of different propagation models for the estimation of the topside ionosphere and plasmasphere with an ensemble Kalman filter
Comparison of quiet-time ionospheric total electron content from the IRI-2016 model and from gridded and station-level GPS observations
Performance of the IRI-2016 over Santa Maria, a Brazilian low-latitude station located in the central region of the South American Magnetic Anomaly (SAMA)
High-resolution vertical total electron content maps based on multi-scale B-spline representations
Validation and application of optimal ionospheric shell height model for single-site estimation of total electron content
Extending the coverage area of regional ionosphere maps using a support vector machine algorithm
Patrick Mungufeni, Sripathi Samireddipalle, Yenca Migoya-Orué, and Yong Ha Kim
Ann. Geophys., 38, 1203–1215, https://doi.org/10.5194/angeo-38-1203-2020, https://doi.org/10.5194/angeo-38-1203-2020, 2020
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This study developed a model of total electron content (TEC) over the African region. The TEC data were derived from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Data during geomagnetically quiet time for the years 2008–2011 and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were used to fit the data for the model.
Tatjana Gerzen, David Minkwitz, Michael Schmidt, and Eren Erdogan
Ann. Geophys., 38, 1171–1189, https://doi.org/10.5194/angeo-38-1171-2020, https://doi.org/10.5194/angeo-38-1171-2020, 2020
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We focus on reconstructing the topside ionosphere and plasmasphere and assimilating the space-based Global Navigation Satellite System slant total electron content (STEC) measurements with an ensemble Kalman filter (EnKF). We present methods for realizing the propagation step without a physical model. We investigate the capability of our estimations to reconstruct independent STEC and electron density measurements. We compare the EnKF approach with SMART+ and the 3D ionosphere model NeQuick.
Gizaw Mengistu Tsidu and Mulugeta Melaku Zegeye
Ann. Geophys., 38, 725–748, https://doi.org/10.5194/angeo-38-725-2020, https://doi.org/10.5194/angeo-38-725-2020, 2020
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The performance of the IRI-2016 model in simulating GPS-TEC is assessed based on various statistical tools during two distinct solar activity periods. In particular, the categorical metrics used in the study to assess the performance of the empirical and climatological IRI-2016 model at the margins of the TEC distribution reveal remarkable model skill in simulating the observed tails of the TEC distribution, which is much better than accurately simulating the observed climatology as designed.
Juliano Moro, Jiyao Xu, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Régia Pereira Silva, Sony Su Chen, Giorgio Arlan da Silva Picanço, Liu Zhengkuan, Hui Li, Chunxiao Yan, Chi Wang, and Nelson Jorge Schuch
Ann. Geophys., 38, 457–466, https://doi.org/10.5194/angeo-38-457-2020, https://doi.org/10.5194/angeo-38-457-2020, 2020
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The monthly averages of the F2 critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired by the DPS4-D installed in Santa Maria, Brazil, is compared to the International Reference Ionosphere (IRI-2016) model predictions. It is important to test the performance of the IRI over Santa Maria because it is located in the SAMA, which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals.
Andreas Goss, Michael Schmidt, Eren Erdogan, Barbara Görres, and Florian Seitz
Ann. Geophys., 37, 699–717, https://doi.org/10.5194/angeo-37-699-2019, https://doi.org/10.5194/angeo-37-699-2019, 2019
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This paper describes an approach to model VTEC solely from NRT GNSS observations by generating a multi-scale representation (MSR) based on B-splines. The unknown model parameters are estimated by means of a Kalman filter. A number of products are created which differ both in their spectral and temporal resolution. The validation studies show that the product with the highest resolution, based on NRT input data, is of higher accuracy than others used within the selected investigation time span.
Jiaqi Zhao and Chen Zhou
Ann. Geophys., 37, 263–271, https://doi.org/10.5194/angeo-37-263-2019, https://doi.org/10.5194/angeo-37-263-2019, 2019
Mingyu Kim and Jeongrae Kim
Ann. Geophys., 37, 77–87, https://doi.org/10.5194/angeo-37-77-2019, https://doi.org/10.5194/angeo-37-77-2019, 2019
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Spatial extrapolation of an ionosphere TEC map was carried out using a SVM learning algorithm. There has been much research on the temporal extrapolation or prediction of TEC time series, but the spatial extrapolation has rarely been attempted. Some researchers have performed simultaneous extrapolation both in time and in spatial domains, but this research covers the spatial extrapolation only by using an inner TEC map. This spatial TEC extrapolation can be useful for small countries.
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Short summary
We use satellite data to analyze precursory anomalies of the western China Ms 7.1 Yushu earthquake by analyzing the signal-to-noise ratio (SNR) and using the full-wave model to illustrate a possible mechanism for how the anomalies occurred. The results show that very low-frequency (VLF) radio wave SNR in the ionosphere decreased before the Yushu earthquake. The full-wave simulation results confirm that electron density variation in the lower ionosphere will affect VLF radio signal SNR.
We use satellite data to analyze precursory anomalies of the western China Ms 7.1 Yushu...
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