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Article ; Online: Editorial

Angelo De Santis / Lin Jian / Mirko Piersanti / Xuhui Shen / Chao Xiong / Zeren Zhima

Frontiers in Earth Science, Vol

Near-earth electromagnetic environment and natural hazards disturbances: Volume II

2023 Volume 11

Keywords	natural hazard- ; satellite ; electromagnetic environment ; earthquake ; LAIC ; Science ; Q
Language	English
Publishing date	2023-11-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Editorial

Angelo De Santis / Lin Jian / Mirko Piersanti / Xuhui Shen / Chao Xiong / Zeren Zhima

Frontiers in Environmental Science, Vol

Near-earth electromagnetic environment and natural hazards disturbances

2023 Volume 11

Keywords	natural hazards ; satellite ; electromagnetic environment ; data analysis ; LAIC ; Environmental sciences ; GE1-350
Language	English
Publishing date	2023-11-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Study of the Statistical Characteristics of Artificial Source Signals Based on the CSES

Jianping Huang / Juan Jia / Huichao Yin / Zhong Li / Jinwen Li / Xuhui Shen / Zeren Zhima

Frontiers in Earth Science, Vol

2022 Volume 10

Abstract: The ground-based artificial source electromagnetic signal transmitted to space will form a pair of intensity regions over the station and its conjugate point. In order to study the position and intensity of the strongest points in the two regions, the ... ...

Abstract	The ground-based artificial source electromagnetic signal transmitted to space will form a pair of intensity regions over the station and its conjugate point. In order to study the position and intensity of the strongest points in the two regions, the power-spectrum density (PSD) of the electric field on board the Zhangheng-1 satellite (CSES) was selected when it passed over the NWC artificial source transmitting station. The selected frequency is centered at 19.8 kHz with a bandwidth of 200 Hz. The strongest point is defined as the location with the maximum power spectral density of ±10° around the NWC station within 5 days, which is the revisiting period of the CSES. The results show that statistical characteristics of strongest points vary as day/night, local/conjugate point, longitude/latitude, and different components of electric field vectors. In terms of longitude deviation, it is mostly westward offset at night and on both sides in the day over the NWC but opposite at the conjugate point. In terms of latitude deviations, it is equator-ward at night and the same during the day with a smaller deviation. While over the conjugate point, it is northward offset in the day and both at night with a bigger offset. In terms of intensity, it is stable without obvious seasonal changes over the NWC and its conjugate point. The intensity of PSD is higher at night than during the day. For the PSD intensity of the three components, the descending order over the NWC is Ead, Eab, and Ecd at night and Ecd, Ead, and Eab in the day, and the opposite is true for over the conjugate point.
Keywords	CSES ; NWC station ; conjugate point ; electric power spectrum ; statistical characteristics ; Science ; Q
Subject code	390
Language	English
Publishing date	2022-06-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Study on Electron Density Anomalies Possibly Related to Earthquakes Based on CSES Observations

Chengcheng Han / Rui Yan / Dedalo Marchetti / Weixing Pu / Zeren Zhima / Dapeng Liu / Song Xu / Hengxin Lu / Na Zhou

Remote Sensing, Vol 15, Iss 3354, p

2023 Volume 3354

Abstract: This research examines the correlation between seismic activity and variations in ionospheric electron density (Ne) using the data from the Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES) during nighttime. Statistical ... ...

Abstract	This research examines the correlation between seismic activity and variations in ionospheric electron density (Ne) using the data from the Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES) during nighttime. Statistical analysis of Ms ≥ 6.8 earthquakes that occurred globally between August 2018 and March 2023 is conducted, as well as Ms ≥ 6.0 earthquakes in China during the same period, using the quartile analysis method for fixed revisiting orbits. The main conclusions are that: (1) the larger the magnitude of the earthquake, the more anomalous the phenomena that appear; (2) the anomalies on the east side of the epicenter are significantly higher than those on the west side, and the anomalies in the Northern Hemisphere are mostly distributed southward from the epicenter, while those in the Southern Hemisphere are mostly distributed northward from the epicenter; (3) anomalies appear with a higher frequency on several specific time intervals, including the day of the earthquake (likely co-seismic effect) and 2, 7, and 11 days before the earthquake (possible precursor candidates); and (4) for the 15 earthquakes of Ms ≥ 6.0 in China over the past five years, anomalous Ne mainly occurred southwest of the epicenter, with the highest frequency observed 5 days before the earthquake, and there were continuous anomalous phenomena between 9 days and 5 days before the earthquake. This study concludes that Ne, measured by CSES, can play a fundamental role in studying earthquake-related ionospheric disturbances.
Keywords	CSES ; electron density ; earthquake ; seismic anomaly ; Science ; Q
Subject code	950
Language	English
Publishing date	2023-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Correlation Between Ne and Te Around 14:00 LT in the Topside Ionosphere Observed by CSES, Swarm and CHAMP Satellites

Rui Yan / Chao Xiong / Zeren Zhima / Xuhui Shen / Dapeng Liu / Chao Liu / Yibing Guan / Keying Zhu / Lin Zheng / Fangxian Lv

Frontiers in Earth Science, Vol

2022 Volume 10

Abstract: In this study, we have performed a detailed analysis for the correlation between electron density (Ne) and temperature (Te) at the topside ionosphere. In situ measurements from four satellites have been utilized, including the China Seismo- ... ...

Abstract	In this study, we have performed a detailed analysis for the correlation between electron density (Ne) and temperature (Te) at the topside ionosphere. In situ measurements from four satellites have been utilized, including the China Seismo-Electromagnetic Satellite (CSES), Swarm A and B, as well as the earlier Challenging Minisatellite Payload (CHAMP) satellite. To make a fair comparison, only simultaneous observations between CSES and Swarm A/B have been considered; while for CHAMP, as it doesn’t have overlaps with CSES period, the observations during similar low solar activity years are considered. Our study has been confined to the dayside around 14:00 local time (LT), due to the fixed LT coverage of CSES. Observations from the four satellites show generally consistent relationship between the Ne and Te at the topside ionosphere. When Ne is low, the Te is negative correlated with Ne, while the slop of negative relation becomes shallower or even reverses to a positive relation after Ne exceeds a certain threshold. The slope of Ne/Te relation shows also dependence on season and magnetic latitude (MLat), as the ionospheric Ne and Te themselves are seasonal and MLat dependent. Interestingly, we find two abnormal features of the Swarm Te measurements: 1) when Ne is lower than 1×1011 m−3, Te sometimes becomes very scatter at low and middle latitudes; 2) when Ne is larger than 1×1011 m−3, Te is grouped into two branches at the equatorial and low latitudes. Further analysis reveals that the flags used in the Swarm Level-1 B plasma density product cannot well distinguish the two abnormal features of Te, implying further efforts are needed for the Swarm Te data calibration.
Keywords	China seismo-electromagnetic satellite (CSES) ; electron density (Ne) ; electron temperature (Te) ; correlation of Ne and Te ; abnormal features ; Science ; Q
Subject code	629
Language	English
Publishing date	2022-05-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Detecting the Auroral Oval through CSES-01 Electric Field Measurements in the Ionosphere

Emanuele Papini / Mirko Piersanti / Giulia D’Angelo / Antonio Cicone / Igor Bertello / Alexandra Parmentier / Piero Diego / Pietro Ubertini / Giuseppe Consolini / Zeren Zhima

Remote Sensing, Vol 15, Iss 1568, p

2023 Volume 1568

Abstract: We present the results of a systematic study of the ionospheric electric field in the Auroral Oval (AO) region in the southern hemisphere. We exploit one year of electric field measurements taken by the Electric Field Detector (EFD) on board the Chinese ... ...

Abstract	We present the results of a systematic study of the ionospheric electric field in the Auroral Oval (AO) region in the southern hemisphere. We exploit one year of electric field measurements taken by the Electric Field Detector (EFD) on board the Chinese Seismo-Electromagnetic Satellite-01 (CSES-01), flying at around 500 km altitude in a sun-synchronous orbit. We exploit the high temporal resolution of the EFD to devise a new technique for the detection of CSES-01 crossing of the AO using electric field measurements only. This new technique combines a Median-Weighted Local Variance Measure with Fast Iterative Filtering to automatically isolate high levels of electromagnetic activity caused by, e.g., particle precipitation and Field Aligned Currents (FACs) at auroral latitudes. We validate this new method against other standard proxies, such as the single-FAC product from the Swarm mission and the auroral radiance emission measured by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) units on board the Defense Meteorological Satellite Program (DMSP) constellation. Furthermore, we identify ∼3000 orbits (out of a dataset of ∼10,000) where CSES-01 crosses the AO boundary under conditions of high geomagnetic activity. This dataset represents the first step in the systematic study of the auroral electric field, with many potential applications to space weather, thanks to the large amount of continuous observations of the ionosphere by CSES-01 and the forthcoming CSES-02 mission.
Keywords	auroral ionosphere ; electric field ; ionosphere–magnetosphere coupling ; detection algorithms ; Science ; Q
Subject code	530
Language	English
Publishing date	2023-03-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Annual and semi-annual variations of electron density in the topside ionosphere observed by CSES

Keying Zhu / Rui Yan / Chao Xiong / Lin Zheng / Zeren Zhima / Xuhui Shen / Dapeng Liu / Yibing Guan / Chao Liu / Song Xu / Fangxian Lv / Feng Guo / Na Zhou

Frontiers in Earth Science, Vol

2023 Volume 11

Abstract: In this paper, based on the observations from Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES), the annual/semi-annual variations of electron density (Ne) measured at 02:00 and 14:00 local time (LT) in the topside ionosphere ...

Abstract	In this paper, based on the observations from Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES), the annual/semi-annual variations of electron density (Ne) measured at 02:00 and 14:00 local time (LT) in the topside ionosphere have been analyzed. Results indicated that the Ne exhibits an amplification-linear-saturation with the increase of P10.7 in the daytime, while roughly linear in the nighttime. The annual/semi-annual variations of CSES Ne at around 500 km are found by morphological analysis and Morlet wavelet analysis, with dominant period of 187 days and 374 days. The annual components of longitude-averaged Ne dominate at most magnetic latitudes (Mlats) with maxima around the June solstices in the northern hemisphere and the December solstice in the southern hemisphere (except for the northern hemisphere in the nighttime), while the semi-annual variation dominates at the magnetic equator and low magnetic latitudes with two maxima at equinoxes. The Ne dominant period is characterized by a transition from semi-annual variation at the equator and low magnetic latitudes regions to annual variation at the middle magnetic latitudes region. The annual/semi-annual variations of Ne observed by CSES satellite show a consistent performance with previous studies, and have complemented the ionospheric characteristics at 500 km altitude, especially in the nighttime.
Keywords	(China Seismo-Electromagnetic Satellite) CSES ; morlet wavelet analysis ; annual/semi-annual variations ; NE ; dominant period ; Science ; Q
Subject code	551
Language	English
Publishing date	2023-03-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: An Improved In-Flight Calibration Scheme for CSES Magnetic Field Data

Yanyan Yang / Zeren Zhima / Xuhui Shen / Bin Zhou / Jie Wang / Werner Magnes / Andreas Pollinger / Hengxin Lu / Feng Guo / Roland Lammegger / Na Zhou / Yuanqing Miao / Qiao Tan / Wenjing Li

Remote Sensing, Vol 15, Iss 4578, p

2023 Volume 4578

Abstract: The CSES high precision magnetometer (HPM), consisting of two fluxgate magnetometers (FGM) and one coupled dark state magnetometer (CDSM), has worked successfully for more than 5 years providing continuous magnetic field measurements since the launch of ... ...

Abstract	The CSES high precision magnetometer (HPM), consisting of two fluxgate magnetometers (FGM) and one coupled dark state magnetometer (CDSM), has worked successfully for more than 5 years providing continuous magnetic field measurements since the launch of the CSES in February 2018. After rechecking almost every year’s data, it has become possible to make an improvement to the in-flight intrinsic calibration (to estimate offsets, scale values and non-orthogonality) and alignment (to estimate three Euler angles for the rotation between the orthogonalized sensor coordinates and the coordinate system of the star tracker) of the FGM. The following efforts have been made to achieve this goal: For the sensor calibration, FGM sensor temperature corrections on offsets and scale values have been taken into account to remove seasonal effects. Based on these results, Euler angles have been estimated along with global geomagnetic field modeling to improve the alignment of the FGM sensor. With this, a latitudinal effect in the east component of the originally calibrated data could be reduced. Furthermore, it has become possible to prolong the updating period of all calibration parameters from daily to 10 days, without the separation of dayside and nightside data. The new algorithms optimize routine HPM data processing efficiency and data quality.
Keywords	China Seismo-Electromagnetic Satellite ; high precision magnetometer ; calibration ; fluxgate magnetometer ; LEO magnetic field measurement ; Science ; Q
Subject code	600
Language	English
Publishing date	2023-09-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effects of Solar Proton Events Associated With X-Ray Flares on Near-Earth Electron and Proton Fluxes Based on ZH-1 Satellite Observations

Lu Wang / Zhenxia Zhang / Xunhui Shen / Xinqiao Li / Xiaohua Liang / Zeren Zhima / Wei Chu / Feng Guo / Na Zhou / Huaran Chen / Daihui Wei

Frontiers in Earth Science, Vol

2022 Volume 10

Abstract: Solar eruptions can cause violent effects on the space environment. Electromagnetic radiation from solar flares will be the first to arrive on the Earth at the speed of light, followed by solar energetic charged particles. The last to appear will be ... ...

Abstract	Solar eruptions can cause violent effects on the space environment. Electromagnetic radiation from solar flares will be the first to arrive on the Earth at the speed of light, followed by solar energetic charged particles. The last to appear will be coronal mass ejections and geomagnetic storms. Based on observations of ZH-1 satellite, we report three strong disturbed space environment events, all of them with solar proton events (SPEs), and analyze the driving mechanisms: 1) On 29 November 2020, an M4.4 flare accompanied with a full halo CME caused a gradual SPE, which was mainly driven by CME shocks. 2) On 28 May 2021, a C9.4 flare brought an impulsive SPE, which was accelerated by the flare. The heliolongitude of this small flare was 63°W, near the footpoint of the magnetic field line leading from the Sun to the Earth. 3) On 28 October 2021, a full-halo CME accompanied with an X1.1 flare brought a gradual SPE. On 2 November 2021, another fast full halo CME accompanied with flare was ejected. The faster CME of November 2 caught up and swept up the slower CME of November 1, and subsequently caused a severe geomagnetic storm (minimum Dst = -101) and a high-energy electron storm on November 4. The observations of the above three space environmental events confirm that the data quality of the high-energy particle package (HEPP) from ZH-1 is highly reliable and accurate and is highly advantageous to monitoring the variation of energetic particles and X-rays in the radiation belt of the Earth during solar activities.
Keywords	solar x-ray flares ; solar proton event ; CSES satellite ; geomagnetic storm ; coronal mass ejections ; ZH-1 satellite ; Science ; Q
Subject code	520
Language	English
Publishing date	2022-06-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Investigation of Precursors in VLF Subionospheric Signals Related to Strong Earthquakes (M>7) in Western China and Possible Explanations

Shufan Zhao / Xuhui Shen / Li Liao / Zeren Zhima / Chen Zhou / Zhuangkai Wang / Jing Cui / Hengxin Lu

Remote Sensing, Vol 12, Iss 3563, p

2020 Volume 3563

Abstract: Earthquakes may disturb the lower ionosphere through various coupling mechanisms during their seismogenic and coseismic periods. The VLF signal radiated from ground-based transmitters is affected when it passes near the disturbed region above the ... ...

Abstract	Earthquakes may disturb the lower ionosphere through various coupling mechanisms during their seismogenic and coseismic periods. The VLF signal radiated from ground-based transmitters is affected when it passes near the disturbed region above the seismogenic area, and this anomaly can be recorded by ground-based VLF receivers. In this paper, the seismic anomalies before two strong earthquakes (M>7) that occurred in western China were detected using the ground-based observation of VLF signal; the possible reasons for the anomalies were discussed using full wave simulation. The amplitude of the VLF signals observed by the link between NOV, KHA transmitter, and VLF receivers at Ya’an and Tonghai show obvious anomaly by nighttime fluctuation analysis. The simulated results demonstrate that the anomalies could have been induced by ascending/descending of the bottom height of the ionosphere, caused by depletion/increase in D region electron density. The simulated result also illustrates that terminator time shift could have been induced by descending of the bottom boundary of the ionosphere, which is due to modal interference between different wave modes.
Keywords	precursory of strong earthquakes ; VLF radio wave ; nighttime fluctuation ; seismic anomalies ; ionospheric disturbance ; full-wave model ; Science ; Q
Subject code	550
Language	English
Publishing date	2020-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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