Concentric gravity waves (CGWs) in the middle and upper atmosphere show wave-coupling processes between the lower atmosphere and the middle and upper atmosphere. In this research, we analyzed a case of CGWs detected simultaneously by the AIRS (Atmospheric Infrared Sounder) and the VIIRS/DNB (Day/Night Band of the Visible Infrared Imager Radiometer Suite) in the stratosphere and mesosphere. Results showed that gravity waves (GWs) were generated by the collocated Hurricane Bejisa on the island of Mauritius. The AIRS data showed arc-like phase fronts of GWs with horizontal wavelengths of 190 and 150 km at 21:08 coordinated universal time (UTC) on 1 January 2014 and at 10:00 UTC on 2 January 2014, whereas the DNB observed arced GWs with horizontal wavelengths of 60 and 150 km in the same geographic regions at 22:24 UTC. The characteristics of CGW parameters in the stratosphere (~40 km) and the mesosphere (~87 km), such as the vertical wavelength, intrinsic frequency, and intrinsic horizontal phase speed, were first derived together with the background winds from ERA5 reanalysis data and Horizontal Wind Model data through the dispersion relationship of GWs and the wind-filtering theory.
{"title":"Case study on stratospheric and mesospheric concentric gravity waves generated by deep convection","authors":"GuoChun Shi, Xiong Hu, ZhiGang Yao, WenJie Guo, MingChen Sun, XiaoYan Gong","doi":"10.26464/epp2021002","DOIUrl":"10.26464/epp2021002","url":null,"abstract":"<p>Concentric gravity waves (CGWs) in the middle and upper atmosphere show wave-coupling processes between the lower atmosphere and the middle and upper atmosphere. In this research, we analyzed a case of CGWs detected simultaneously by the AIRS (Atmospheric Infrared Sounder) and the VIIRS/DNB (Day/Night Band of the Visible Infrared Imager Radiometer Suite) in the stratosphere and mesosphere. Results showed that gravity waves (GWs) were generated by the collocated Hurricane Bejisa on the island of Mauritius. The AIRS data showed arc-like phase fronts of GWs with horizontal wavelengths of 190 and 150 km at 21:08 coordinated universal time (UTC) on 1 January 2014 and at 10:00 UTC on 2 January 2014, whereas the DNB observed arced GWs with horizontal wavelengths of 60 and 150 km in the same geographic regions at 22:24 UTC. The characteristics of CGW parameters in the stratosphere (~40 km) and the mesosphere (~87 km), such as the vertical wavelength, intrinsic frequency, and intrinsic horizontal phase speed, were first derived together with the background winds from ERA5 reanalysis data and Horizontal Wind Model data through the dispersion relationship of GWs and the wind-filtering theory.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"79-89"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41789581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ShuTao Yao, ZongShun Yue, QuanQi Shi, Alexander William Degeling, HuiShan Fu, AnMin Tian, Hui Zhang, Andrew Vu, RuiLong Guo, ZhongHua Yao, Ji Liu, Qiu-Gang Zong, XuZhi Zhou, JingHuan Li, WenYa Li, HongQiao Hu, YangYang Liu, WeiJie Sun
Kinetic-scale magnetic holes (KSMHs) are structures characterized by a significant magnetic depression with a length scale on the order of the proton gyroradius. These structures have been investigated in recent studies in near-Earth space, and found to be closely related to energy conversion and particle acceleration, wave-particle interactions, magnetic reconnection, and turbulence at the kinetic-scale. However, there are still several major issues of the KSMHs that need further study — including (a) the source of these structures (locally generated in near-Earth space, or carried by the solar wind), (b) the environmental conditions leading to their generation, and (c) their spatio-temporal characteristics. In this study, KSMHs in near-Earth space are investigated statistically using data from the Magnetospheric Multiscale mission. Approximately 200,000 events were observed from September 2015 to March 2020. Occurrence rates of such structures in the solar wind, magnetosheath, and magnetotail were obtained. We find that KSMHs occur in the magnetosheath at rates far above their occurrence in the solar wind. This indicates that most of the structures are generated locally in the magnetosheath, rather than advected with the solar wind. Moreover, KSMHs occur in the downstream region of the quasi-parallel shock at rates significantly higher than in the downstream region of the quasi-perpendicular shock, indicating a relationship with the turbulent plasma environment. Close to the magnetopause, we find that the depths of KSMHs decrease as their temporal-scale increases. We also find that the spatial-scales of the KSMHs near the subsolar magnetosheath are smaller than those in the flanks. Furthermore, their global distribution shows a significant dawn-dusk asymmetry (duskside dominating) in the magnetotail.
{"title":"Statistical properties of kinetic-scale magnetic holes in terrestrial space","authors":"ShuTao Yao, ZongShun Yue, QuanQi Shi, Alexander William Degeling, HuiShan Fu, AnMin Tian, Hui Zhang, Andrew Vu, RuiLong Guo, ZhongHua Yao, Ji Liu, Qiu-Gang Zong, XuZhi Zhou, JingHuan Li, WenYa Li, HongQiao Hu, YangYang Liu, WeiJie Sun","doi":"10.26464/epp2021011","DOIUrl":"10.26464/epp2021011","url":null,"abstract":"<p>Kinetic-scale magnetic holes (KSMHs) are structures characterized by a significant magnetic depression with a length scale on the order of the proton gyroradius. These structures have been investigated in recent studies in near-Earth space, and found to be closely related to energy conversion and particle acceleration, wave-particle interactions, magnetic reconnection, and turbulence at the kinetic-scale. However, there are still several major issues of the KSMHs that need further study — including (a) the source of these structures (locally generated in near-Earth space, or carried by the solar wind), (b) the environmental conditions leading to their generation, and (c) their spatio-temporal characteristics. In this study, KSMHs in near-Earth space are investigated statistically using data from the Magnetospheric Multiscale mission. Approximately 200,000 events were observed from September 2015 to March 2020. Occurrence rates of such structures in the solar wind, magnetosheath, and magnetotail were obtained. We find that KSMHs occur in the magnetosheath at rates far above their occurrence in the solar wind. This indicates that most of the structures are generated locally in the magnetosheath, rather than advected with the solar wind. Moreover, KSMHs occur in the downstream region of the quasi-parallel shock at rates significantly higher than in the downstream region of the quasi-perpendicular shock, indicating a relationship with the turbulent plasma environment. Close to the magnetopause, we find that the depths of KSMHs decrease as their temporal-scale increases. We also find that the spatial-scales of the KSMHs near the subsolar magnetosheath are smaller than those in the flanks. Furthermore, their global distribution shows a significant dawn-dusk asymmetry (duskside dominating) in the magnetotail.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"63-72"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43631725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polar Mesosphere Summer Echoes (PMSEs) are very strong radar echoes observed at altitudes near the polar summer mesopause. One of the essential properties of these radar echoes is that they can give useful diagnostic information about the physics of the scattering process. In this paper, the related characteristics of PMSEs measured with the European Incoherent SCATter Very High Frequency (EISCAT VHF) 224 MHz radar on 13–15 July 2010 are studied at different elevation angles from 78° to 90°. It is found that the PMSEs peak power and strongest PMSEs average power occur at the same elevation angles. Also interesting is that the strongest PMSEs occur at off-vertical angles when a PMSEs has a layered (multilayer) structure. And reflection may have more significant effects on PMSEs when there are double or multilayer PMSEs. Possible explanations regarding these observations are discussed.
{"title":"Characteristic analysis of layered PMSEs measured with different elevation angles at VHF based on an experimental case","authors":"ShuCan Ge, HaiLong Li, Bin Xu, Tong Xu, Lin Meng, MaoYan Wang, Abdel Hannachi, MengYan Zhu, Lina Broman, Safi Ullah, Abdur Rauf","doi":"10.26464/epp2021001","DOIUrl":"10.26464/epp2021001","url":null,"abstract":"<p>Polar Mesosphere Summer Echoes (PMSEs) are very strong radar echoes observed at altitudes near the polar summer mesopause. One of the essential properties of these radar echoes is that they can give useful diagnostic information about the physics of the scattering process. In this paper, the related characteristics of PMSEs measured with the European Incoherent SCATter Very High Frequency (EISCAT VHF) 224 MHz radar on 13–15 July 2010 are studied at different elevation angles from 78° to 90°. It is found that the PMSEs peak power and strongest PMSEs average power occur at the same elevation angles. Also interesting is that the strongest PMSEs occur at off-vertical angles when a PMSEs has a layered (multilayer) structure. And reflection may have more significant effects on PMSEs when there are double or multilayer PMSEs. Possible explanations regarding these observations are discussed.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"42-51"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48923518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field (IMF), to investigate how the nighttime poleward wind (30°–50° magnetic latitude and 19–22 magnetic local time) responds to subauroral polarization streams (SAPS) that commence at different universal times (UTs). The SAPS effects on the poleward winds show a remarkable UT variation, with weaker magnitudes at 00 and 12 UT than at 06 and 18 UT. The strongest poleward wind emerges when SAPS commence at 06 UT, and the weakest poleward wind develops when SAPS occur at 00 UT. A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 UT. Meanwhile, the effect of ion drag is important in the modulation of the poleward wind velocity at 06 and 18 UT. This is caused by the misalignment of the geomagnetic and geographic coordinate systems, resulting in a large component of ion drag in the geographically northward (southward) direction due to channel orientation of the SAPS at 06 and 18 UT (00 and 12 UT). The Coriolis force effect induced by westward winds maximizes (minimizes) when SAPS commence at 12 UT (00 UT). The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force, but with an opposite effect.
本研究使用热层电离层电动力学环流模型(TIEGCM),在与南向行星际磁场(IMF)密切相关的地磁扰动条件下,研究夜间向极地风(30°-50°磁纬度和19-22磁地方时)如何响应于不同世界时(ut)开始的亚极光极化流(SAPS)。SAPS对极地风的影响表现出显著的UT变化,在00和12 UT的强度弱于06和18 UT。世界时06分SAPS开始时,极风最强,世界时00分SAPS开始时,极风最弱。对模式结果的诊断分析表明,压力梯度在0时和12时对极向风的发展更为突出。同时,离子阻力在06和18 UT的极向风速调制中起重要作用。这是由于地磁和地理坐标系的不对齐造成的,由于SAPS在06和18 UT(00和12 UT)的通道方向,导致离子阻力在地理上向北(南)方向的很大一部分。西风引起的科里奥利力效应在12 UT (00 UT)开始时达到最大(最小)。由加速的西风引起的离心力与科里奥利力表现出相似的UT变化,但效果相反。
{"title":"Nighttime meridional neutral wind responses to SAPS simulated by the TIEGCM: A universal time effect","authors":"KeDeng Zhang, Hui Wang, WenBin Wang, Jing Liu, ShunRong Zhang, Cheng Sheng","doi":"10.26464/epp2021004","DOIUrl":"10.26464/epp2021004","url":null,"abstract":"<p>The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field (IMF), to investigate how the nighttime poleward wind (30°–50° magnetic latitude and 19–22 magnetic local time) responds to subauroral polarization streams (SAPS) that commence at different universal times (UTs). The SAPS effects on the poleward winds show a remarkable UT variation, with weaker magnitudes at 00 and 12 UT than at 06 and 18 UT. The strongest poleward wind emerges when SAPS commence at 06 UT, and the weakest poleward wind develops when SAPS occur at 00 UT. A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 UT. Meanwhile, the effect of ion drag is important in the modulation of the poleward wind velocity at 06 and 18 UT. This is caused by the misalignment of the geomagnetic and geographic coordinate systems, resulting in a large component of ion drag in the geographically northward (southward) direction due to channel orientation of the SAPS at 06 and 18 UT (00 and 12 UT). The Coriolis force effect induced by westward winds maximizes (minimizes) when SAPS commence at 12 UT (00 UT). The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force, but with an opposite effect.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"52-62"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46009158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report a simultaneous observation of two band electromagnetic ion cyclotron (EMIC) waves and toroidal Alfvén waves by the Van Allen Probe mission. Through wave frequency analyses, the mass density ρ is found to be locally peaked at the magnetic equator. Perpendicular fluxes of ions (< 100 eV) increase simultaneously with the appearances of EMIC waves, indicating a heating of these ions by EMIC waves. In addition, the measured ion distributions also support the equatorial peak formation, which accords with the result of the frequency analyses. The formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations, which are triggered by EMIC waves’ perpendicular heating on low energy ions.
{"title":"Formation of the mass density peak at the magnetospheric equator triggered by EMIC waves","authors":"ZuXiang Xue, ZhiGang Yuan, XiongDong Yu, Huang ShiYong, Zheng Qiao","doi":"10.26464/epp2021008","DOIUrl":"10.26464/epp2021008","url":null,"abstract":"<p>We report a simultaneous observation of two band electromagnetic ion cyclotron (EMIC) waves and toroidal Alfvén waves by the Van Allen Probe mission. Through wave frequency analyses, the mass density <i>ρ</i> is found to be locally peaked at the magnetic equator. Perpendicular fluxes of ions (< 100 eV) increase simultaneously with the appearances of EMIC waves, indicating a heating of these ions by EMIC waves. In addition, the measured ion distributions also support the equatorial peak formation, which accords with the result of the frequency analyses. The formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations, which are triggered by EMIC waves’ perpendicular heating on low energy ions.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"32-41"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44502728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jie Dong, Gabriele Cambiotti, HanJiang Wen, Roberto Sabadini, WenKe Sun
In this paper, we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities. From the results of applying models 1066A (continuous) and 1066B (discontinuous), we find that the difference in Love numbers of strike-slip and horizontal tensile sources are bigger than dip-slip and vertical tensile sources. Taken collectively, discontinuities have major effects on Green’s functions of four independent sources. For the near-field coseismic deformations of the 2013 Okhotsk earthquake (Mw 8.3), the overall differences between theoretical calculations in vertical displacement, geoid, and gravity changes caused by discontinuities are 10.52 percent, 9.07 percent and 6.19 percent, with RMS errors of 0.624 mm, 0.029 mm, and 0.063 μGal, respectively. The difference in far-field displacements is small, compared with GPS data, and we can neglect this effect. For the shallow earthquake, 2011 Tohoku-Oki earthquake (Mw 9.0), the differences in near-field displacements are 0.030 m (N-S), 0.093 m (E-W), and 0.025 m (up-down) in our study area with the ARIA slip model, which gives results closer to GPS data than those from the USGS model. The difference in vertical displacements and gravity changes on the Earth’s surface caused by discontinuities are larger than 10 percent. The difference in the theoretical gravity changes at spatially fixed points truncated to degrees 60, as required by GRACE data, is 0.0016 μGal and the discrepancy is 11 percent, with the theoretical spatial gravity changes from 1066B closer to observations than from 1066A. The results show that an Earth model with discontinuities in the medium has a large effect on the calculated coseismic deformations.
本文研究了1066个地球模型计算的同震形变如何受到模型处理地球不连续面的方式的影响。从1066A(连续)和1066B(不连续)模型的应用结果来看,走滑和水平张拉震源Love数的差异大于倾滑和垂直张拉震源Love数的差异。总的来说,不连续对四个独立来源的格林函数有主要影响。对于2013年鄂霍次克8.3级地震近场同震形变,不连续面引起的垂直位移、大地面和重力变化的理论计算总体差异为10.52%、9.07%和6.19%,均方根误差分别为0.624 mm、0.029 mm和0.063 μGal。与GPS数据相比,远场位移的差异很小,我们可以忽略这种影响。对于2011年Tohoku-Oki地震(Mw 9.0)的浅层地震,ARIA滑动模型在研究区内的近场位移差异为0.030 m (N-S), 0.093 m (E-W)和0.025 m(上下),与USGS模型相比,结果更接近GPS数据。不连续性引起的地球表面垂直位移和重力变化的差异大于10%。在GRACE数据要求的空间不动点截断到60度的理论重力变化差值为0.0016 μGal,差值为11%,1066B的理论空间重力变化比1066A的更接近观测值。结果表明,具有介质不连续的地球模型对计算的同震变形有较大影响。
{"title":"Treatment of discontinuities inside Earth models: Effects on computed coseismic deformations","authors":"Jie Dong, Gabriele Cambiotti, HanJiang Wen, Roberto Sabadini, WenKe Sun","doi":"10.26464/epp2021010","DOIUrl":"10.26464/epp2021010","url":null,"abstract":"<p>In this paper, we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities. From the results of applying models 1066A (continuous) and 1066B (discontinuous), we find that the difference in Love numbers of strike-slip and horizontal tensile sources are bigger than dip-slip and vertical tensile sources. Taken collectively, discontinuities have major effects on Green’s functions of four independent sources. For the near-field coseismic deformations of the 2013 Okhotsk earthquake (<i>M</i><sub>w</sub> 8.3), the overall differences between theoretical calculations in vertical displacement, geoid, and gravity changes caused by discontinuities are 10.52 percent, 9.07 percent and 6.19 percent, with RMS errors of 0.624 mm, 0.029 mm, and 0.063 μGal, respectively. The difference in far-field displacements is small, compared with GPS data, and we can neglect this effect. For the shallow earthquake, 2011 Tohoku-Oki earthquake (<i>M</i><sub>w</sub> 9.0), the differences in near-field displacements are 0.030 m (N-S), 0.093 m (E-W), and 0.025 m (up-down) in our study area with the ARIA slip model, which gives results closer to GPS data than those from the USGS model. The difference in vertical displacements and gravity changes on the Earth’s surface caused by discontinuities are larger than 10 percent. The difference in the theoretical gravity changes at spatially fixed points truncated to degrees 60, as required by GRACE data, is 0.0016 μGal and the discrepancy is 11 percent, with the theoretical spatial gravity changes from 1066B closer to observations than from 1066A. The results show that an Earth model with discontinuities in the medium has a large effect on the calculated coseismic deformations.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"90-104"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43863157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
XinAn Yue, WeiXing Wan, Han Xiao, LingQi Zeng, ChangHai Ke, BaiQi Ning, Feng Ding, BiQiang Zhao, Lin Jin, Chen Li, MingYuan Li, JunYi Wang, HongLian Hao, Ning Zhang
In the past decades, the Incoherent Scatter Radar (ISR) has been demonstrated to be one of the most powerful instruments for ionosphere monitoring. The Institute of Geology and Geophysics at the Chinese Academy of Sciences was founded to build a state-of-the-art phased-array ISR at Sanya (18.3°N, 109.6°E), a low-latitude station on Hainan Island, named the Sanya ISR (SYISR). As a first step, a prototype radar system consisting of eight subarrays (SYISR-8) was built to reduce the technical risk of producing the entire large array. In this work, we have summarized the preliminary experimental results based on the SYISR-8. The amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring network. The mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°, respectively, which met the basic requirements. The beam directivity was confirmed by crossing screen of the International Space Station. The SYISR-8 was further used to detect the tropospheric wind profile and meteors. The derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS measurements. The SYISR-8 was able to observe several typical meteor echoes, such as the meteor head echo, range-spread trail echo, and specular trail echo. These results confirmed the validity and reliability of the SYISR-8 system, thereby reducing the technical risk of producing the entire large array of the SYISR to some extent.
{"title":"Preliminary experimental results by the prototype of Sanya Incoherent Scatter Radar","authors":"XinAn Yue, WeiXing Wan, Han Xiao, LingQi Zeng, ChangHai Ke, BaiQi Ning, Feng Ding, BiQiang Zhao, Lin Jin, Chen Li, MingYuan Li, JunYi Wang, HongLian Hao, Ning Zhang","doi":"10.26464/epp2020063","DOIUrl":"10.26464/epp2020063","url":null,"abstract":"<p>In the past decades, the Incoherent Scatter Radar (ISR) has been demonstrated to be one of the most powerful instruments for ionosphere monitoring. The Institute of Geology and Geophysics at the Chinese Academy of Sciences was founded to build a state-of-the-art phased-array ISR at Sanya (18.3°N, 109.6°E), a low-latitude station on Hainan Island, named the Sanya ISR (SYISR). As a first step, a prototype radar system consisting of eight subarrays (SYISR-8) was built to reduce the technical risk of producing the entire large array. In this work, we have summarized the preliminary experimental results based on the SYISR-8. The amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring network. The mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°, respectively, which met the basic requirements. The beam directivity was confirmed by crossing screen of the International Space Station. The SYISR-8 was further used to detect the tropospheric wind profile and meteors. The derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS measurements. The SYISR-8 was able to observe several typical meteor echoes, such as the meteor head echo, range-spread trail echo, and specular trail echo. These results confirmed the validity and reliability of the SYISR-8 system, thereby reducing the technical risk of producing the entire large array of the SYISR to some extent.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"4 6","pages":"579-587"},"PeriodicalIF":2.9,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44983507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tao Tang, Jun Yang, QuanQi Shi, AnMin Tian, Shi-Chen Bai, Alexander William Degeling, SuiYan Fu, JingXian Liu, Tong Shao, ZeYuan Sun
Earth's aurora is a luminescent phenomenon generated by the interaction between magnetospheric precipitating particles and the upper atmosphere; it plays an important role in magnetosphere–ionosphere (M-I) coupling. The transpolar arc (TPA) is a discrete auroral arc distributed in the noon-midnight direction poleward of the auroral oval and connects the dayside to the nightside sectors of the auroral oval. Studying the seasonal variation of TPA events can help us better understand the long-term variation of the interaction between the solar wind, the magnetosphere, and M-I coupling. However, a statistical study of the seasonal variation of TPA incidence has not previously been carried out. In this paper, we have identified 532 TPA events from the IMAGE database (2000–2005) and the Polar database (1996–2002), and calculated the incidence of TPA events for different months. We find a semiannual variation in TPA incidence. Clear peaks in the incidence of TPAs occur in March and September; a less pronounced peak appears in November. We also examine seasonal variation in the northward interplanetary magnetic field (IMF) over the same time period. The intensity and occurrence rate of the northward IMF exhibit patterns similar to that of the TPA incidence. Having studied IMFB