Temporal change of EIA asymmetry revealed by a beacon receiver network in Southeast Asia

Watthanasangmechai, Kornyanat; Yamamoto, M.; Saito, Akinori; Maruyama, Takashi; Yokoyama, T.; Nishioka, Michi; Ishii, Mamoru

doi:10.1186/s40623-015-0252-9

Cited by 15 publications

(8 citation statements)

References 36 publications

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“…The data gap caused by the solar panels can be seen on the north side of the mapping image. An enhancement of the total count of the red channel caused by an enhancement of the 630-nm emission can be seen around the latitude of 5° S. This enhancement was interpreted to be caused by the EIA, because the magnetic latitude of the enhancement is consistent with the typical magnetic latitude of the EIA (e.g., Watthanasangmechai et al 2014Watthanasangmechai et al , 2015. The total counts of the enhancement on the east side of the FOV were larger than those on the west side.…”

Section: Horizontal Airglow Structuresmentioning

confidence: 80%

Calibration of imaging parameters for space-borne airglow photography using city light positions

2016

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Abstract:A new method for calibrating imaging parameters of photographs taken from the International Space Station (ISS) is presented in this report. Airglow in the mesosphere and the F-region ionosphere was captured on the limb of the Earth with a digital single-lens reflex camera from the ISS by astronauts. To utilize the photographs as scientific data, imaging parameters, such as the angle of view, exact position, and orientation of the camera, should be determined because they are not measured at the time of imaging. A new calibration method using city light positions shown in the photographs was developed to determine these imaging parameters with high accuracy suitable for airglow study. Applying the pinhole camera model, the apparent city light positions on the photograph are matched with the actual city light locations on Earth, which are derived from the global nighttime stable light map data obtained by the Defense Meteorological Satellite Program satellite. The correct imaging parameters are determined in an iterative process by matching the apparent positions on the image with the actual city light locations. We applied this calibration method to photographs taken on August 26, 2014, and confirmed that the result is correct. The precision of the calibration was evaluated by comparing the results from six different photographs with the same imaging parameters. The precisions in determining the camera position and orientation are estimated to be ±2.2 km and ±0.08°, respectively. The 0.08° difference in the orientation yields a 2.9-km difference at a tangential point of 90 km in altitude. The airglow structures in the photographs were mapped to geographical points using the calibrated imaging parameters and compared with a simultaneous observation by the Visible and near-Infrared Spectral Imager of the Ionosphere, Mesosphere, Upper Atmosphere, and Plasmasphere mapping mission installed on the ISS. The comparison shows good agreements and supports the validity of the calibration. This calibration technique makes it possible to utilize photographs taken on low-Earth-orbit satellites in the nighttime as a reference for the airglow and aurora structures.

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Section: Horizontal Airglow Structuresmentioning

confidence: 80%

Calibration of imaging parameters for space-borne airglow photography using city light positions

2016

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“…The RMSE is larger in low latitude regions than in middle and high latitude regions and shows two peaks near 20 ±  . The reason for this may be the EIA, which makes the variation of the F2-layer in low latitude regions a non-linear dynamic process and a result of complex physical systems [47]. It can be seen that the RMSE is larger in equinoxes than in solstices over both the northern and southern hemispheres.…”

Section: Modeling Resultsmentioning

confidence: 99%

A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation

et al. 2019

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To facilitate F2-layer peak density (NmF2) modeling, a nonlinear polynomial model approach based on global NmF2 observational data from ionospheric radio occultation (IRO) measurements onboard the CHAMP, GRACE, and COSMIC satellites, is presented in this paper. We divided the globe into 63 slices from 80°S to 80°N according to geomagnetic latitude. A Nonlinear Polynomial Peak Density Model (NPPDM) was constructed by a multivariable least squares fitting to NmF2 measurements in each latitude slice and the dependencies of NmF2 on solar activity, geographical longitude, universal time, and day of year were described. The model was designed for quiet and moderate geomagnetic conditions (Ap ≤ 32). Using independent radio occultation data, quantitative analysis was made. The correlation coefficients between NPPDM predictions and IRO data were 0.91 in 2002 and 0.82 in 2005. The results show that NPPDM performs better than IRI2016 and Neustrelitz Peak Density Model (NPDM) under low solar activity, while it undergoes performance degradation under high solar activity. Using data from twelve ionosonde stations, the accuracy of NPPDM was found to be better than that of NPDM and comparable to that of IRI2016. Additionally, NPPDM can well simulate the variations and distributions of NmF2 and describe some ionospheric features, including the equatorial ionization anomaly, the mid-latitude trough, and the wavenumber-four longitudinal structure.

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“…The electrodynamical process in EIA regions is complicated, the asymmetry and strength of EIA would be mainly affected by the disturbed neutral wind and electric field. Watthanasangmechai et al [2015] indicated that the neutral wind is typically considered as the primary source of EIA interhemispheric asymmetry, whereas the zonal electric field is secondary. Thus, when the normal neutral wind is disrupted, the interhemispheric asymmetry may be changed.…”

Section: Discussionmentioning

confidence: 99%

The strength and hemispheric asymmetry of Equatorial Ionization Anomaly during two geomagnetic storms in 2013 from Global Ionosphere Map and SAMI2

Luo

Zhu

Lan

2016

Journal of Atmospheric and Solar-Terrestrial Physics

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The variations of the strength and the hemispheric asymmetry of EIA were studied by Global Ionosphere Map(GIM) and SAMI2 during two geomagnetic storm periods in March and June 2013. Compared with the 30-days median TEC, the TEC at the two crests of EIA had small variations while the TEC at the trough had a more remarkable variation for the two storms after the SSC. The TEC difference between the two EIA peaks had an increase or decrease several hours after the SSC, the asymmetry between the two crests of EIA represented by the defined asymmetry index has no obvious variations except several hours after the SSC, and EIA strength represented by the Crest-to-Trough Ratio (CTR) had a remarkable increase one day after the SSC day for March storm and decrease several hours after the SSC for June storm. The variations last several hours, with more than 40% variations compared with the value during the quiet period. The EIA peaks were also found to move toward the equator after the SSC during the two storms. The simulation from SAMI2 and HWM07 also shows that EIA crests would move toward the equator during storm time and EIA strength would decrease, which suggests that the disturbed neutral wind and disturbed electric field may be important factors affecting the EIA during the storm periods.

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Temporal change of EIA asymmetry revealed by a beacon receiver network in Southeast Asia

Cited by 15 publications

References 36 publications

Calibration of imaging parameters for space-borne airglow photography using city light positions

Calibration of imaging parameters for space-borne airglow photography using city light positions

A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation

The strength and hemispheric asymmetry of Equatorial Ionization Anomaly during two geomagnetic storms in 2013 from Global Ionosphere Map and SAMI2

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