Earth and Planetary Physics最新文献

{"title":"Far-field coseismic gravity changes related to the 2015 MW7.8 Nepal (Gorkha) earthquake observed by superconducting gravimeters in mainland China","authors":"LeLin Xing,&nbsp;ZiWei Liu,&nbsp;JianGang Jia,&nbsp;ShuQing Wu,&nbsp;ZhengSong Chen,&nbsp;XiaoWei Niu","doi":"10.26464/epp2021018","DOIUrl":"10.26464/epp2021018","url":null,"abstract":"<p>Using data from five SGs at four stations in mainland China, obvious permanent gravity changes caused by the 2015 <i>M</i>_W 7.8 Nepal (Gorkha) earthquake were detected. We analyzed the gravity effects from ground vertical deformation (VD) using co-site continuous GPS (cGPS) data collocated at the Lijiang and the Wuhan station, and hydrological effects using GLDAS models and groundwater level records. After removing these effects, SG observations before and after the earthquake revealed obvious permanent gravity changes: −3.0 μGal, 7.3 μGal and 8.0 μGal at Lhasa, Lijiang and Wuhan station, respectively. We found that the gravity changes cannot be explained by the results of dislocation theory.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 2","pages":"141-148"},"PeriodicalIF":2.9,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43500203","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}

{"title":"Correlating the interplanetary factors to distinguish extreme and major geomagnetic storms","authors":"Ragini Balachandran,&nbsp;Li-Jen Chen,&nbsp;Shan Wang,&nbsp;Mei-Ching Fok","doi":"10.26464/epp2021015","DOIUrl":"10.26464/epp2021015","url":null,"abstract":"<p>We investigate the correlation between Disturbance Storm Time (<i>Dst</i>) characteristics and solar wind conditions for the main phase of geomagnetic storms, seeking possible factors that distinguish extreme storms (minimum <i>Dst</i> &lt;−250 nT) and major storms (minimum <i>Dst</i> &lt;−100 nT). In our analysis of 170 storms, there is a marked correlation between the average rate of change of <i>Dst</i> during a storm's main phase (Δ<i>Dst</i>/Δ<i>t</i>) and the storm's minimum <i>Dst</i>, indicating a faster Δ<i>Dst</i>/Δ<i>t</i> as storm intensity increases. Extreme events add a new regime to Δ<i>Dst</i>/Δ<i>t</i>, the hourly time derivative of <i>Dst</i> (d<i>Dst</i>/d<i>t</i>), and sustained periods of large amplitudes for southward interplanetary magnetic field <i>B_z</i> and solar wind convection electric field <i>E_y</i>. We find that <i>E_y</i> is a less efficient driver of d<i>Dst</i>/d<i>t</i> for extreme storms compared to major storms, even after incorporating the effects of solar wind pressure and ring current decay. When minimum <i>Dst</i> is correlated with minimum <i>B_z</i>, we observe a similar divergence, with extreme storms tending to have more negative <i>Dst</i> than the trend predicted on the basis of major storms. Our results enable further improvements in existing models for storm predictions, including extreme events, based on interplanetary measurements.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 2","pages":"180-186"},"PeriodicalIF":2.9,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43688526","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}

{"title":"A new inversion method for reconstruction of plasmaspheric He+ density from EUV images","authors":"Ya Huang,&nbsp;Lei Dai,&nbsp;Chi Wang,&nbsp;RongLan Xu,&nbsp;Liang Li","doi":"10.26464/epp2021020","DOIUrl":"10.26464/epp2021020","url":null,"abstract":"<p>The Computer Tomography (CT) method is used for remote sensing the Earth's plasmasphere. One challenge for image reconstruction is insufficient projection data, mainly caused by limited projection angles. In this study, we apply the Algebraic Reconstruction Technique (ART) and the minimization of the image Total Variation (TV) method, with a combination of priori knowledge of north-south symmetry, to reconstruct plasmaspheric He⁺ density from simulated EUV images. The results demonstrate that incorporating priori assumption can be particularly useful when the projection data is insufficient. This method has good performance even with a projection angle of less than 150 degrees. The method of our study is expected to have applications in the Soft X-ray Imager (SXI) reconstruction for the Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE) mission.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 2","pages":"218-222"},"PeriodicalIF":2.9,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48817663","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}

{"title":"Morphology and possible origins of the Perm anomaly in the lowermost mantle of Earth","authors":"YuMei He,&nbsp;LianXing Wen,&nbsp;Yann Capdeville","doi":"10.26464/epp2021009","DOIUrl":"10.26464/epp2021009","url":null,"abstract":"<p>We have constrained a small-scale, dome-shaped low-velocity structure near the core-mantle boundary (CMB) of Earth beneath Perm (the Perm anomaly) using travel-time analysis and three-dimensional (3-D) forward waveform modeling of seismic data sampling of the mantle. The best-fitting dome-shaped model centers at 60.0°E, 50.5°N, and has a height of 400 km and a radius that increases from 200 km at the top to 450 km at the CMB. Its velocity reduction varies from 0% at the top to –3.0% at 240km above the CMB to –3.5% at the CMB. A surrounding 240-km-thick high-velocity D'' structure has also been detected. The Perm anomaly may represent a stable small-scale chemical pile in the lowermost mantle, although the hypothesis of a developing mantle plume cannot be ruled out.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"105-116"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45165254","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}

{"title":"Wide-field aurora imager onboard Fengyun satellite: Data products and validation","authors":"GuangXing Ding,&nbsp;JiaWei Li,&nbsp;XiaoXin Zhang,&nbsp;Fei He,&nbsp;LingPing He,&nbsp;KeFei Song,&nbsp;Liang Sun,&nbsp;Shuang Dai,&nbsp;ShiJie Liu,&nbsp;Bo Chen,&nbsp;Chao Yu,&nbsp;XiuQing Hu,&nbsp;SongYan Gu,&nbsp;ZhongDong Yang,&nbsp;Peng Zhang","doi":"10.26464/epp2021003","DOIUrl":"10.26464/epp2021003","url":null,"abstract":"<p>New observations of auroras based on the wide-field aurora imager (WAI) onboard Fengyun-3D (FY-3D) satellite are exhibited in this paper. Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F18). Dynamic variations of the aurora with the solar wind, interplanetary magnetic field (IMF) parameters, and the SYM-H index are also investigated. The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics. Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth's space weather. Since the configuration of aurora is a good indicator of the solar wind-magnetosphere-ionosphere (SW-M-I) coupling system, and can reflect the disturbance of the space environment, the WAI will provide important data to help us to study the physical processes in space.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"73-78"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49436237","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}

{"title":"Is Solar Wind electron precipitation a source of neutral heating in the nightside Martian upper atmosphere?","authors":"LongKang Dai,&nbsp;Jun Cui,&nbsp;DanDan Niu,&nbsp;Hao Gu,&nbsp;YuTian Cao,&nbsp;XiaoShu Wu,&nbsp;HaiRong Lai","doi":"10.26464/epp2021012","DOIUrl":"10.26464/epp2021012","url":null,"abstract":"<p>Solar Wind (SW) electron precipitation is able to deposit a substantial amount of energy in the nightside Martian upper atmosphere, potentially exerting an influence on its thermal structure. This study serves as the first investigation of such an issue, with the aid of the simultaneous measurements of both neutral density and energetic electron intensity made on board the recent Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We report that, from a statistical point of view, the existing measurements do not support a scenario of noticeable neutral heating via SW electron precipitation. However, during 3%−4% of the MAVEN orbits for which data are available, strong correlation between nightside temperature and electron intensity is observed, manifested as collocated enhancements in both parameters, as compared to the surrounding regions. In addition, our analysis also indicates that neutral heating via SW electron precipitation tends to be more effective at altitudes below 160 km for integrated electron intensities above 0.01 ergs·cm⁻²·s⁻¹ over the energy range of 3−450 eV. The results reported here highlight the necessity of incorporating SW electron precipitation as a heat source in the nightside Martian upper atmosphere under extreme circumstances such as during interplanetary coronal mass ejections.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"1-10"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46183130","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}

{"title":"An updated constraint on the local stratigraphy at the Chang'E-4 landing site","authors":"YiRen Chang,&nbsp;ZhiYong Xiao,&nbsp;YiChen Wang,&nbsp;ChunYu Ding,&nbsp;Jun Cui,&nbsp;YuZhen Cai","doi":"10.26464/epp2021007","DOIUrl":"10.26464/epp2021007","url":null,"abstract":"<p>The Chang’E-4 mission has been exploring the lunar farside. Two scientific targets of the rover onboard are (1) resolving the possible mineralogy related to the South Pole-Aitken basin and (2) understanding the subsurface processes at the lunar farside. Publications to date that are based on the reflectance spectra and radar data obtained by the rover have shown a persistent inconsistency about the local stratigraphy. To explain both the abnormal surface topography at the landing site and the unexpected radargram observed by the rover, the Alder crater has been frequently reported to be older than the mare basalts at that landing site. However, this argument is not supported by earlier geological mapping nor recent crater statistics. Resolving this controversy is critical for a full understanding of the geological history of the landing area and for correct interpretations of the scientific data returned. Employing detailed crater statistics, rigorous statistical analyses, and an updated crater chronology function, this study is determined to resolve the relative ages of the Alder crater, Finsen crater, and the mare basalts on the floor of Von Kármán. Our results reveal that while background secondaries and local resurfacing have widely occurred in the study area, affecting age determinations, the statistics are significant enough to conclude that the Alder crater is the oldest among the three targets. This independent constraint is consistent with both the crosscutting relationships of different terrains in this area and global stratigraphic mapping. Our results exclude Alder as a possible contributor of the post-mare deposits at the landing site, appealing for a more systematic stratigraphy study to resolve the provenances of these deposits.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"19-31"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43366994","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}

{"title":"Dielectric permittivity of dusty plasma in the Earth's mesosphere","authors":"Hui Li,&nbsp;Jian Wu","doi":"10.26464/epp2021006","DOIUrl":"10.26464/epp2021006","url":null,"abstract":"<p>This paper deals with the dielectric permittivity of dusty plasma in the earth's mesosphere. We give expressions for the complex dielectric permittivity of dusty plasma, taking into account the effects of the dust charging process and magnetic field. We discuss the dielectric permittivity of dusty plasma in several cases, such as high frequency approximation, parallel propagation in MF/HF band, and effects of plasma movement. Finally, the expressions are employed to study the phenomenon of radar echoes from the polar summer mesosphere. We report that dielectric permittivity caused by the dust charging process gives a radar cross section proportional to <i>ω</i>^–4 and produces a number density of charged dust that agrees with measurements of mesopheric radar echoes.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"117-120"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42879575","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}

{"title":"Annual Meeting minutes of the Chinese Geoscience Union, 2020","authors":"QingHua Huang","doi":"10.26464/epp2021013","DOIUrl":"10.26464/epp2021013","url":null,"abstract":"&lt;p&gt;The Seventh Annual Meeting of the Chinese Geoscience Union was held in Chongqing Yuelai International Convention Center, from October 18 to 21 2020, together with the 36&lt;sup&gt;th&lt;/sup&gt; Annual Meeting of Chinese Geophysical Society which was held. This annual meeting convened one main venue and 31 academic conference venues, hosting 92 sessions with 51 of them focused on geophysics (including one English session). In addition, there were also six union-wide invited talks, 5 presentations on the frontiers of geophysics, and 8 award lectures for the 2020 Fu Chengyi Young Scientist Awardees. The annual meeting received about 3200 abstracts, 2150 of which were oral presentations and 950 as posters. In total, there were about 4000 participants from the scientific community and more than 80 exhibitors.&lt;/p&gt;&lt;p&gt;The 2020 annual meeting started on the afternoon of October 18th, chaired by the Chairman of the Chinese Geophysical Society Prof. Chen Xiaofei, an academician of the Chinese Academy of Sciences. Academician Zheng Yongfei announced the outstanding paper awardees of the 2019 annual meeting. Academician Xu Yigang from Guangzhou Institute of Geochemistry, Chinese Academy of Sciences delivered an invited talk titled “Deep processes and habitable Earth”, and Academician Gao Rui from Sun Yat-sen University delivered an invited talk titled “Deep seismic reflection profiles, dense seismic arrays, and MT jointly reveal the deep process of land-land collision in the Qinghai-Tibet Plateau”. Academician Pan Yongxin from the Institute of Geology and Geophysics, Chinese Academy of Sciences, delivered an invited presentation titled “The Explorations of Mars: review and perspective”. Academician Xiao Wenjiao from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences gave an invited presentation titled \"Multiple Collages and Central Asian Continent Accretion\"; Academician Cui Peng from Chengdu Institute of Mountain Disasters and Environment, Chinese Academy of Sciences and Ministry of Water Resources gave an invited presentation titled \"Disaster Risk of Sichuan-Tibet Railway and its Prevention and Control Research\"; and Professor-level senior engineer Zhao Bangliu of China Petroleum Exploration and Production Branch gave an invited talk titled \"The key role of geophysical technology in the exploration and development of shale gas in the Sichuan Basin\".&lt;/p&gt;&lt;p&gt;On the morning of October 18th, the Chairman of the Chinese Geophysical Society Academician Chen Xiaofei presided over a forum on the frontiers of geophysics at the 36th Annual Conference of the Chinese Geophysics Society. Professor Zhang Keke from the Macau University of Science and Technology gave a report on \"Macau High-precision Geomagnetic Satellite Constellation: Scientific Significance and Application Value\"; Research Professor Ding Zhifeng from the Institute of Geophysics, China Earthquake Administration gave a report on \"Research Progress of Seismic Array Detection of Deep Structures","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"121"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48878541","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}

{"title":"Some features of effective radius and variance of dust particles in numerical simulations of the dust climate on Mars","authors":"Chi-Fong Wong,&nbsp;Chow Kim-Chiu,&nbsp;Kwing L. Chan,&nbsp;Jing Xiao,&nbsp;Yemeng Wang","doi":"10.26464/epp2021005","DOIUrl":"10.26464/epp2021005","url":null,"abstract":"<p>Airborne dust is an important constituent in the Martian atmosphere because of its radiative interaction with the atmospheric circulation. Dust size is one crucial factor in determining this effect. In reality dust sizes are varied; however, in numerical modeling of dust processes, dust size has usually been described by choice of a particular size distribution function, or by use of fixed values of effective radius (ER) and effective variance (EV). In this work, we present analytical expressions that have been derived to specify ER and EV for <i>N</i>-bin dust schemes, based on a model-calculated dust mixing ratio. Numerical simulations based on this approach thus would consider the effects of variable ER on the atmospheric radiation and their interaction. Results have revealed some interesting features of the dust distribution parameters, such as seasonal and spatial variation of ER and EV, which are generally consistent with some previous observational and modeling studies. Compared with the usual approach of using a fixed ER, simulation results from the present approach suggest that the variability of ER can have significant effects on the simulated thermal field of the Martian atmosphere.</p>","PeriodicalId":45246,"journal":{"name":"Earth and Planetary Physics","volume":"5 1","pages":"11-18"},"PeriodicalIF":2.9,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.26464/epp2021005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45674982","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}