Yuan Lei, Xing Cao, BinBin Ni, Song Fu, TaoRong Luo, XiaoYu Wang
Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space, it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes. In the present study, we develop a forecast model of radiation belt electron fluxes based on the data assimilation method, in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations. Our forecast model can cover the entire outer radiation belt with a high temporal resolution (1 hour) and a spatial resolution of 0.25 L over a wide range of both electron energy (0.1–5.0 MeV) and pitch angle (5°–90°). On the basis of this model, we forecast hourly electron fluxes for the next 1, 2, and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance. Our model can reasonably predict the storm-time evolution of radiation belt electrons with high prediction efficiency (up to ~0.8–1). The best prediction performance is found for ~0.3–3 MeV electrons at L = ~3.25–4.5, which extends to higher L and lower energies with increasing pitch angle. Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes, and the model has both scientific significance and practical implications.
{"title":"A data assimilation-based forecast model of outer radiation belt electron fluxes","authors":"Yuan Lei, Xing Cao, BinBin Ni, Song Fu, TaoRong Luo, XiaoYu Wang","doi":"10.26464/epp2023079","DOIUrl":"https://doi.org/10.26464/epp2023079","url":null,"abstract":"Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space, it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes. In the present study, we develop a forecast model of radiation belt electron fluxes based on the data assimilation method, in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations. Our forecast model can cover the entire outer radiation belt with a high temporal resolution (1 hour) and a spatial resolution of 0.25 <italic>L</italic> over a wide range of both electron energy (0.1–5.0 MeV) and pitch angle (5°–90°). On the basis of this model, we forecast hourly electron fluxes for the next 1, 2, and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance. Our model can reasonably predict the storm-time evolution of radiation belt electrons with high prediction efficiency (up to ~0.8–1). The best prediction performance is found for ~0.3–3 MeV electrons at <italic>L</italic> = ~3.25–4.5, which extends to higher <italic>L</italic> and lower energies with increasing pitch angle. Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes, and the model has both scientific significance and practical implications.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135495254","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}
Wen Yi, XiangHui Xue, MaoLin Lu, Jie Zeng, HaiLun Ye, JianFei Wu, Chong Wang, TingDi Chen
The atmospheric temperatures and densities in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. In this study, more than 9 years of mesopause temperatures and relative densities estimated by using ambipolar diffusion coefficient measurements observed by the Mengcheng meteor radar (33.4°N, 116.5°E) are presented. The intercomparison between the meteor radar and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere by Broadband Emission Radiometry (TIMED/SABER) and EOS Aura/Microwave Limb Sounder (MLS) observations indicates that the meteor radar temperatures and densities agree well with the simultaneous satellite measurements. The annual variations dominate mesopause temperatures, with a maximum during winter and a minimum during summer. The mesopause relative densities also show annual variations with strong maxima near the spring equinox and weak maxima before the winter solstices and with a minimum during summer. In addition, the mesopause density exhibits a structure similar to that of the zonal wind; as the zonal wind flow is eastward (westward), the mesopause density decreases (increases). At the same time, the meridional wind shows a structure similar to that of the mesopause temperature; as the meridional wind shows northward (southward) enhancements, the mesopause temperature increases (decreases). Simultaneous horizontal wind, temperature, and density observations provide multiple mesospheric parameters for investigating mesospheric dynamics and thermodynamic processes and have the potential to improve widely used empirical atmospheric models.
{"title":"Mesopause temperatures and relative densities at midlatitudes observed by the Mengcheng meteor radar","authors":"Wen Yi, XiangHui Xue, MaoLin Lu, Jie Zeng, HaiLun Ye, JianFei Wu, Chong Wang, TingDi Chen","doi":"10.26464/epp2023083","DOIUrl":"https://doi.org/10.26464/epp2023083","url":null,"abstract":"The atmospheric temperatures and densities in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. In this study, more than 9 years of mesopause temperatures and relative densities estimated by using ambipolar diffusion coefficient measurements observed by the Mengcheng meteor radar (33.4°N, 116.5°E) are presented. The intercomparison between the meteor radar and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere by Broadband Emission Radiometry (TIMED/SABER) and EOS Aura/Microwave Limb Sounder (MLS) observations indicates that the meteor radar temperatures and densities agree well with the simultaneous satellite measurements. The annual variations dominate mesopause temperatures, with a maximum during winter and a minimum during summer. The mesopause relative densities also show annual variations with strong maxima near the spring equinox and weak maxima before the winter solstices and with a minimum during summer. In addition, the mesopause density exhibits a structure similar to that of the zonal wind; as the zonal wind flow is eastward (westward), the mesopause density decreases (increases). At the same time, the meridional wind shows a structure similar to that of the mesopause temperature; as the meridional wind shows northward (southward) enhancements, the mesopause temperature increases (decreases). Simultaneous horizontal wind, temperature, and density observations provide multiple mesospheric parameters for investigating mesospheric dynamics and thermodynamic processes and have the potential to improve widely used empirical atmospheric models.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135650144","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}
Hui Zhang, Jun Zhong, SuiYan Fu, ZuYin Pu, Yong Wei, Lun Xie, LiBo Liu and Qi’an Chen
Large-scale inverted-V channels of upflowing oxygen ions are frequently identified out of the data of Cluster at all the local time near the open-closed field line boundary over Earth’s high-latitude ionospheres. These energy spectrum structures generally cooccurred with downward propagating MHD Alfvén waves which had cascaded down into kinetic regime of plasma, and the transverse acceleration of the oxygen ions in the center of the structures are interpreted as the integrated energization by these waves along the channels. Upward parallel electric fields, a key characteristic of kinetic Alfvén waves, are also observed within the channels, which may not only contribute to lift the ions but also precipitate aurora electrons that might initiate the ion upflow in the ionosphere below. Statistics on five-year observations of Cluster show that the channels typically form during geomagnetic perturbations, particularly when solar wind dynamic pressure is high or highly fluctuated. Near the open-closed field line boundary, the stronger the wave power, the higher the upward oxygen flux and the higher the beam energy, indicating that these waves provide a simple but efficient way to drive the oxygen upflows.
{"title":"Large-scale inverted-V channels of upflowing oxygen ions pumped by Alfvén waves","authors":"Hui Zhang, Jun Zhong, SuiYan Fu, ZuYin Pu, Yong Wei, Lun Xie, LiBo Liu and Qi’an Chen","doi":"10.26464/epp2023082","DOIUrl":"https://doi.org/10.26464/epp2023082","url":null,"abstract":"Large-scale inverted-V channels of upflowing oxygen ions are frequently identified out of the data of Cluster at all the local time near the open-closed field line boundary over Earth’s high-latitude ionospheres. These energy spectrum structures generally cooccurred with downward propagating MHD Alfvén waves which had cascaded down into kinetic regime of plasma, and the transverse acceleration of the oxygen ions in the center of the structures are interpreted as the integrated energization by these waves along the channels. Upward parallel electric fields, a key characteristic of kinetic Alfvén waves, are also observed within the channels, which may not only contribute to lift the ions but also precipitate aurora electrons that might initiate the ion upflow in the ionosphere below. Statistics on five-year observations of Cluster show that the channels typically form during geomagnetic perturbations, particularly when solar wind dynamic pressure is high or highly fluctuated. Near the open-closed field line boundary, the stronger the wave power, the higher the upward oxygen flux and the higher the beam energy, indicating that these waves provide a simple but efficient way to drive the oxygen upflows.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"167 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135650154","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}
Xin Sun, DaLian Shi, Zhen Chen, Ran Li, WeiWei Cao, Jun Zhu, YongLin Bai, Le Wang, and Fei He
The Scientific Experimental system in Near SpacE (SENSE) consists of different types of instruments that will be installed on a balloon-based platform to characterize near-space environmental parameters. As one of the main scientific payloads, the middle and near ultraviolet spectrograph (MN-UVS) will provide full spectra coverage from middle ultraviolet (MUV, 200 nm-300 nm) to near ultraviolet (NUV, 300 nm-400 nm) with a spectral resolution of 2 nm. Its primary mission is to acquire data regarding the UV radiation background of the upper atmosphere. The MN-UVS is made up of six primary components: a fore-optical module, an imaging grating module, a UV intensified focal plane module, a titanium alloy frame, a spectrometer control module, and a data processing module. This paper presents in detail the engineering design of each functional unit of the MN-UVS, as well as the instrument’s radiometric calibration, wavelength calibration, impact test, and low-pressure discharge test. Furthermore, we are able to report ground test and flight test results of high quality, showing that the MN-UVS has a promising future in upcoming near-space applications.
{"title":"Middle and near ultraviolet spectrograph of the Scientific Experimental system in Near SpacE (SENSE)","authors":"Xin Sun, DaLian Shi, Zhen Chen, Ran Li, WeiWei Cao, Jun Zhu, YongLin Bai, Le Wang, and Fei He","doi":"10.26464/epp2023081","DOIUrl":"https://doi.org/10.26464/epp2023081","url":null,"abstract":"The Scientific Experimental system in Near SpacE (SENSE) consists of different types of instruments that will be installed on a balloon-based platform to characterize near-space environmental parameters. As one of the main scientific payloads, the middle and near ultraviolet spectrograph (MN-UVS) will provide full spectra coverage from middle ultraviolet (MUV, 200 nm-300 nm) to near ultraviolet (NUV, 300 nm-400 nm) with a spectral resolution of 2 nm. Its primary mission is to acquire data regarding the UV radiation background of the upper atmosphere. The MN-UVS is made up of six primary components: a fore-optical module, an imaging grating module, a UV intensified focal plane module, a titanium alloy frame, a spectrometer control module, and a data processing module. This paper presents in detail the engineering design of each functional unit of the MN-UVS, as well as the instrument’s radiometric calibration, wavelength calibration, impact test, and low-pressure discharge test. Furthermore, we are able to report ground test and flight test results of high quality, showing that the MN-UVS has a promising future in upcoming near-space applications.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"390 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136258064","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}
The principal moments of inertia (PMIs) with the principal axes are usually taken as the dynamic figure parameters of Mars; they can be deduced from satellite-observed degree-two gravitational potentials in recent global gravity models and from the dynamic ellipticities resulting from precession observations. These PMIs are natural and significant for the geodetic, geophysical, and geodynamic problems of Mars, which are functions of internal density distributions. In this study, a closed and concise formula for determining the PMIs of the entire planet and its core was developed based on the second invariants of gravity and a multipole expansion. We deduced the polar oblateness J2 and the equatorial ellipticity J22 of Mars to be 1.9566 × 10−3 and 6.3106 × 10−5, respectively. The preferred principal moments of inertia of Mars are A = 2.66589 × 1036 kg·m2, B = 2.66775 × 1036 kg·m2, and C = 2.68125 × 1036 kg·m2. These values indicate that Mar is slightly triaxial. The equatorial principal moment of inertia of the Martian core is 1.46008 × 1035 kg·m2, accounting for ~5.47% of the planet’s PMI; this result is critical for investigating the density and size of the core of Mars, and the planet’s free core nutation.
{"title":"Determining the moment of inertia of triaxial Mars with updated global gravity models","authors":"ChangYi Xu, Yan Jiang","doi":"10.26464/epp2023084","DOIUrl":"https://doi.org/10.26464/epp2023084","url":null,"abstract":"The principal moments of inertia (PMIs) with the principal axes are usually taken as the dynamic figure parameters of Mars; they can be deduced from satellite-observed degree-two gravitational potentials in recent global gravity models and from the dynamic ellipticities resulting from precession observations. These PMIs are natural and significant for the geodetic, geophysical, and geodynamic problems of Mars, which are functions of internal density distributions. In this study, a closed and concise formula for determining the PMIs of the entire planet and its core was developed based on the second invariants of gravity and a multipole expansion. We deduced the polar oblateness <italic>J</italic><sub>2</sub> and the equatorial ellipticity <italic>J</italic><sub>22</sub> of Mars to be 1.9566 × 10<sup>−3</sup> and 6.3106 × 10<sup>−5</sup>, respectively. The preferred principal moments of inertia of Mars are <italic>A</italic> = 2.66589 × 10<sup>36</sup> kg·m<sup>2</sup>, <italic>B</italic> = 2.66775 × 10<sup>36</sup> kg·m<sup>2</sup>, and <italic>C</italic> = 2.68125 × 10<sup>36</sup> kg·m<sup>2</sup>. These values indicate that Mar is slightly triaxial. The equatorial principal moment of inertia of the Martian core is 1.46008 × 10<sup>35</sup> kg·m<sup>2</sup>, accounting for ~5.47% of the planet’s PMI; this result is critical for investigating the density and size of the core of Mars, and the planet’s free core nutation.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136258803","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}
FeiFan Liu, BaoYou Zhu, HeLin Zhou, GaoPeng Lu, Ming Ma, and JiuHou Lei
Narrow bipolar events (NBEs) are one sort of intriguing intra-cloud discharges that receive enormous interest in the lightning community. They come with two polarities dominating at different altitudes in thunderclouds. The sources of negative NBEs are usually located near the top of thunderclouds, and positive NBEs are at the middle levels. NBEs may occur at the onset of lightning, but the electrical properties of NBEs remain not well understood. Here, we present the first comparative study on the electrical characteristics of negative and positive NBEs. An improved method based on the transmission line model is applied to derive electrical parameters from the fast electric field change waveforms of 1673 positive NBEs and 364 negative NBEs recorded by the Jianghuai Area Sferic Array (JASA) in China. It is found that negative NBEs occurring at high altitudes tend to produce a narrower current pulse and take a shorter time to traverse the channel than their positive counterparts. Moreover, a larger portion of negative NBEs is associated with slightly greater peak current moment but smaller overall charge moment compared to their positive counterparts. The discrepancies in electrical properties between negative and positive NBEs reported in our work suggest the difference in charge distributions at different altitudes in NBE-producing thunderstorms.
{"title":"A comparative study of the electrical characteristics of positive and negative narrow bipolar events","authors":"FeiFan Liu, BaoYou Zhu, HeLin Zhou, GaoPeng Lu, Ming Ma, and JiuHou Lei","doi":"10.26464/epp2023085","DOIUrl":"https://doi.org/10.26464/epp2023085","url":null,"abstract":"Narrow bipolar events (NBEs) are one sort of intriguing intra-cloud discharges that receive enormous interest in the lightning community. They come with two polarities dominating at different altitudes in thunderclouds. The sources of negative NBEs are usually located near the top of thunderclouds, and positive NBEs are at the middle levels. NBEs may occur at the onset of lightning, but the electrical properties of NBEs remain not well understood. Here, we present the first comparative study on the electrical characteristics of negative and positive NBEs. An improved method based on the transmission line model is applied to derive electrical parameters from the fast electric field change waveforms of 1673 positive NBEs and 364 negative NBEs recorded by the Jianghuai Area Sferic Array (JASA) in China. It is found that negative NBEs occurring at high altitudes tend to produce a narrower current pulse and take a shorter time to traverse the channel than their positive counterparts. Moreover, a larger portion of negative NBEs is associated with slightly greater peak current moment but smaller overall charge moment compared to their positive counterparts. The discrepancies in electrical properties between negative and positive NBEs reported in our work suggest the difference in charge distributions at different altitudes in NBE-producing thunderstorms.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136258063","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}
The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions. In this study, we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa plasma. By solving the kinetic linear dispersion equation, we explore the sensitivity of growth rates to the spectral index κ of a bi-kappa distribution under different plasma conditions, including a variety of plasma beta beta _hp and temperature anisotropy A_hp values of hot protons. Furthermore, a concise, analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables: the spectral index and the plasma beta and temperature anisotropy of hot protons. Our results show that as the κ-value increases, the instability bandwidth narrows and the maximum growth rate increases significantly. For higher beta _hp and A_hp , the maximum instability undergoes a sharp increase as well. When our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory, the results generally exhibit good agreement between them. Especially under the circumstances of large κ-values and high beta _hp and A_hp , the scalings of maximum growth rates primarily accurately model the numerical solutions. Our analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.
{"title":"Scalings for the Alfvén-cyclotron instability in a bi-kappa plasma","authors":"YueQun Lou, Xing Cao, MingYu Wu, BinBin Ni, TieLong Zhang","doi":"10.26464/epp2023080","DOIUrl":"https://doi.org/10.26464/epp2023080","url":null,"abstract":"The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions. In this study, we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa plasma. By solving the kinetic linear dispersion equation, we explore the sensitivity of growth rates to the spectral index <italic>κ</italic> of a bi-kappa distribution under different plasma conditions, including a variety of plasma beta <inline-formula><span class=\"inline-formula-span\"> beta _hp </span><img text_id='M1' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M1.jpg'><alternatives></alternatives></inline-formula> and temperature anisotropy <inline-formula><span class=\"inline-formula-span\"> A_hp </span><img text_id='M2' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M2.jpg'><alternatives></alternatives></inline-formula> values of hot protons. Furthermore, a concise, analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables: the spectral index and the plasma beta and temperature anisotropy of hot protons. Our results show that as the <italic>κ</italic>-value increases, the instability bandwidth narrows and the maximum growth rate increases significantly. For higher <inline-formula><span class=\"inline-formula-span\"> beta _hp </span><img text_id='M1' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M1.jpg'><alternatives></alternatives></inline-formula> and <inline-formula><span class=\"inline-formula-span\"> A_hp </span><img text_id='M2' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M2.jpg'><alternatives></alternatives></inline-formula>, the maximum instability undergoes a sharp increase as well. When our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory, the results generally exhibit good agreement between them. Especially under the circumstances of large <italic>κ</italic>-values and high <inline-formula><span class=\"inline-formula-span\"> beta _hp </span><img text_id='M1' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M1.jpg'><alternatives></alternatives></inline-formula> and <inline-formula><span class=\"inline-formula-span\"> A_hp </span><img text_id='M2' class='formula-img' style='display:none;' src='RA415-louyuequn-F_M2.jpg'><alternatives></alternatives></inline-formula>, the scalings of maximum growth rates primarily accurately model the numerical solutions. Our analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135610299","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}
PengCheng Zhou, William L. Ellsworth, HongFeng Yang, Yen Joe Tan, Gregory C. Beroza, MinHan Sheng, RiSheng Chu
Seismic hazard assessment and risk mitigation depend critically on rapid analysis and characterization of earthquake sequences. Increasing seismicity in shale gas blocks of the Sichuan Basin, China, has presented a serious challenge to monitoring and managing the seismicity itself. In this study, to detect events we apply a machine-learning-based phase picker (PhaseNet) to continuous seismic data collected between November 2015 and November 2016 from a temporary network covering the Weiyuan Shale Gas Blocks (SGB). Both P- and S-phases are picked and associated for location. We refine the velocity model by using detected explosions and earthquakes and then relocate the detected events using our new velocity model. Our detections and absolute relocations provide the basis for building a high-precision earthquake catalog. Our primary catalog contains about 60 times as many earthquakes as those in the catalog of the Chinese Earthquake Network Center (CENC), which used only the sparsely distributed permanent stations. We also measure the local magnitude and achieve magnitude completeness of ML0. We relocate clusters of events, showing sequential migration patterns overlapping with horizontal well branches around several well pads in the Wei202 and Wei204 blocks. Our results demonstrate the applicability of a machine-learning phase picker to a dense seismic network. The algorithms can facilitate rapid characterization of earthquake sequences.
{"title":"Machine-learning-facilitated earthquake and anthropogenic source detections near the Weiyuan Shale Gas Blocks, Sichuan, China","authors":"PengCheng Zhou, William L. Ellsworth, HongFeng Yang, Yen Joe Tan, Gregory C. Beroza, MinHan Sheng, RiSheng Chu","doi":"10.26464/epp2021053","DOIUrl":"10.26464/epp2021053","url":null,"abstract":"<p>Seismic hazard assessment and risk mitigation depend critically on rapid analysis and characterization of earthquake sequences. Increasing seismicity in shale gas blocks of the Sichuan Basin, China, has presented a serious challenge to monitoring and managing the seismicity itself. In this study, to detect events we apply a machine-learning-based phase picker (PhaseNet) to continuous seismic data collected between November 2015 and November 2016 from a temporary network covering the Weiyuan Shale Gas Blocks (SGB). Both P- and S-phases are picked and associated for location. We refine the velocity model by using detected explosions and earthquakes and then relocate the detected events using our new velocity model. Our detections and absolute relocations provide the basis for building a high-precision earthquake catalog. Our primary catalog contains about 60 times as many earthquakes as those in the catalog of the Chinese Earthquake Network Center (CENC), which used only the sparsely distributed permanent stations. We also measure the local magnitude and achieve magnitude completeness of <i>M</i><sub>L</sub>0. We relocate clusters of events, showing sequential migration patterns overlapping with horizontal well branches around several well pads in the Wei202 and Wei204 blocks. Our results demonstrate the applicability of a machine-learning phase picker to a dense seismic network. The algorithms can facilitate rapid characterization of earthquake sequences.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 6","pages":"532-546"},"PeriodicalIF":2.9,"publicationDate":"2021-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021053","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42686694","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}
HongFeng Yang, XiaoWei Chen, Rebecca Harrington, YaJing Liu
<p>It has been long recognized that a variety of anthropogenic activities may cause earthquakes (Ellsworth et al., <span>2013</span>; Yang HF et al., <span>2017</span>). In the recent decades, induced earthquakes have been found in many settings and become a growing concern, in particular for regions that are undergoing with resource development. For instance, damaging earthquakes in the shale gas fields of Sichuan Basin and Oklahoma have been suggested to be associated with hydraulic fracturing and wastewater disposal (Lei XL et al., <span>2020</span>; Keranen et al., <span>2014</span>), respectively. Understanding mechanisms of induced earthquakes is critical for reducing the associated risks, yet demands integrated efforts of seismic and geodetic monitoring, probing hydraulic properties of subsurface structure, as well as geomechanical modeling.</p><p>In this special collection, we present six papers with contents spanning from earthquake monitoring to geomechanical modeling. Wong et al. (<span>2021</span>) and Zhou PC et al. (<span>2021</span>) have applied machine learning techniques to earthquake detection from the data recorded by permanent and a temporary seismic network in the Weiyuan shale gas field, Sichuan Province, respectively. Their newly acquired catalogs show clear improvement compared with those network routine catalogs. Miao SY et al. (<span>2021</span>) developed a new method to locate earthquakes and applied it in an oilfield in Oman and the Changning shale gas field, Sichuan Province. Yang W et al. (<span>2021</span>) proposed a revised local magnitude formula with coefficients calibrated for earthquakes in the Southern Sichuan Basin. Barbour and Beeler (<span>2021</span>) conducted a systematic investigation on deriving poroelastic properties of the Arbukle group in Oklahoma, based on fluid-level response to teleseismic waves. Hemami et al. (<span>2021</span>) conducted 3D fully coupled poroelastic analysis of the Wilzetta fault system and its response to saltwater injection within the Arbuckle group. The following part includes details in each contributed paper.</p><p>For induced seismicity, a complete earthquake catalog is crucial in evaluating the spatial-temporal correlation with anthropogenic activities, however, routine monitoring network is often limited by the station coverage and processing power. Wong et al. (<span>2021</span>) have applied advanced machine learning technique on detecting phase arrivals on the permanent network in the Weiyuan shale gas field, Sichuan Province, China, and find clear improvement in the accuracy of identifying both P and S arrivals. Then they derive differential times from waveform correlation to build a high-resolution earthquake catalog of induced earthquakes in the Weiyuan Area. The improved resolution permits a detailed analysis of the induced earthquakes, including investigation of the spatial and temporal of seismicity surrounding the geological structures activated during a <i
这种方法带来了改进，特别是在信噪比(SNRs)较差或首次到达的情况下。在编制地震目录时，另一个基本而又重要的问题是确定地震的震级。地震局地震级的准确性是地震灾害和风险评估的关键。在容易诱发地震的环境中，交通灯协议严重依赖(如果不是完全依赖)当地报告的震级，这一点尤为明显。然而，根据目前的CNSN国家标准，当震中距离较短(<包括10公里)，也包括用局部密集阵列监测诱发地震活动的情况。yang W et al.(2021)的研究解决了这一迫切需求，提出了一个修正的局部震级公式，其中校正了四川盆地南部地震的系数。2019年在长宁-昭通页岩气田附近用密集节点阵列记录的约7500个事件进行了测试，新公式显著降低了短距离(100米至30公里)的高估。结合相位选择和事件检测的机器学习技术，本研究为当地地震风险表征提供了丰富、可靠的地震活动目录。系数优化协议可以潜在地应用于其他地区和/或未来密集阵列的部署，以进行改进。虽然地震监测对于调查诱发地震至关重要，但了解诱发地震的机制和评估未来诱发地震的风险需要考虑流体和岩石之间相互作用的地质力学模型。Hemami等人(2021)在Wilzetta断层系统上应用了三维全耦合孔隙弹性模型，并计算了其对次表层，特别是Arbuckle组和基底盐水注入的响应。通过建立三维断层几何图形，他们根据地质层和断裂带之间水力关系的假设，计算出断层系统上的应力扰动。然而，数值结果表明，向Brbuckle群注入大量流体往往会使Wilzetta部分断层更接近破坏。地质力学建模的一个关键因素是如何定义一个合理的模型参数范围，特别是对于那些没有直接测量的模型参数。利用近场GPS网络，可以合理地推断地下各层的水力参数(Jiang GY et al.， 2020)。然而，在有诱发地震的地区，密集的近场大地测量并不总是可用的。Barbour和Beeler(2021)利用远震表面波对俄克拉何马arbuckle组的孔隙弹性特性进行了系统研究。通过监测俄克拉何马州Sage县一座改造后的Arbuckle处置井的液位变化，并与同一位置的宽带地震仪记录的远震波进行比较，他们发现了与S波、Love波以及瑞利波相对应的液位变化信号。利用井眼应变计，他们还能够校准从宽带地震记录推断的动态应变，然后使用该动态应变来获得Arbuckle组内的孔隙弹性参数。此外，Arbuckle地层的孔隙弹性响应既具有方位变化性，又具有各向异性，这与最大水平应力方向和断层/裂缝方向等构造应力和应变指标有关。结果还证明了一种利用远震波估计水力特性的可行方法。虽然本文介绍了一系列不同环境下诱发地震的最新研究进展，但诱发地震的机制尚不完全清楚，对诱发地震的减灾也没有达成共识。因此，对诱发地震的进一步研究是迫切需要的，特别是在全球走向碳中和的趋势下，在开发非常规能源和绿色能源的过程中，诱发地震将不可避免。
{"title":"Preface to the special collection of Induced Earthquakes","authors":"HongFeng Yang, XiaoWei Chen, Rebecca Harrington, YaJing Liu","doi":"10.26464/epp2021057","DOIUrl":"10.26464/epp2021057","url":null,"abstract":"<p>It has been long recognized that a variety of anthropogenic activities may cause earthquakes (Ellsworth et al., <span>2013</span>; Yang HF et al., <span>2017</span>). In the recent decades, induced earthquakes have been found in many settings and become a growing concern, in particular for regions that are undergoing with resource development. For instance, damaging earthquakes in the shale gas fields of Sichuan Basin and Oklahoma have been suggested to be associated with hydraulic fracturing and wastewater disposal (Lei XL et al., <span>2020</span>; Keranen et al., <span>2014</span>), respectively. Understanding mechanisms of induced earthquakes is critical for reducing the associated risks, yet demands integrated efforts of seismic and geodetic monitoring, probing hydraulic properties of subsurface structure, as well as geomechanical modeling.</p><p>In this special collection, we present six papers with contents spanning from earthquake monitoring to geomechanical modeling. Wong et al. (<span>2021</span>) and Zhou PC et al. (<span>2021</span>) have applied machine learning techniques to earthquake detection from the data recorded by permanent and a temporary seismic network in the Weiyuan shale gas field, Sichuan Province, respectively. Their newly acquired catalogs show clear improvement compared with those network routine catalogs. Miao SY et al. (<span>2021</span>) developed a new method to locate earthquakes and applied it in an oilfield in Oman and the Changning shale gas field, Sichuan Province. Yang W et al. (<span>2021</span>) proposed a revised local magnitude formula with coefficients calibrated for earthquakes in the Southern Sichuan Basin. Barbour and Beeler (<span>2021</span>) conducted a systematic investigation on deriving poroelastic properties of the Arbukle group in Oklahoma, based on fluid-level response to teleseismic waves. Hemami et al. (<span>2021</span>) conducted 3D fully coupled poroelastic analysis of the Wilzetta fault system and its response to saltwater injection within the Arbuckle group. The following part includes details in each contributed paper.</p><p>For induced seismicity, a complete earthquake catalog is crucial in evaluating the spatial-temporal correlation with anthropogenic activities, however, routine monitoring network is often limited by the station coverage and processing power. Wong et al. (<span>2021</span>) have applied advanced machine learning technique on detecting phase arrivals on the permanent network in the Weiyuan shale gas field, Sichuan Province, China, and find clear improvement in the accuracy of identifying both P and S arrivals. Then they derive differential times from waveform correlation to build a high-resolution earthquake catalog of induced earthquakes in the Weiyuan Area. The improved resolution permits a detailed analysis of the induced earthquakes, including investigation of the spatial and temporal of seismicity surrounding the geological structures activated during a <i","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 6","pages":"483-484"},"PeriodicalIF":2.9,"publicationDate":"2021-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48507646","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：