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Mesospheric tide comparisons at low latitudes observed by two collocated meteor radars

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Earth and Planetary Physics 2025年第1期9卷 54-68页

作者： Jian Li Wen Yi XiangHui Xue Jie Zeng HaiLun Ye JianYuan Wang JinSong Chen Na Li TingDi Chen Chinese Academy of Sciences(CAS)key laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology Anhui Mengcheng Geophysics National Observation and Research StationUniversity of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230026China Collaborative Innovation Center of Astronautical Science and Technology Harbin 150001China National key laboratory of Electromagnetic Environment China Research Institute of Radiowave PropagationQingdao 266107China Yunnan Kunming Electromagnetic Environment National Observation and Research Station Qujing Kunming 655000China

Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)*** this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December *** two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,***,overall good agreement is observed between the two radars in terms of horizontal winds and tide *** results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal ***,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal *** investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both *** finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor *** of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.

关键词： mesosphere and lower thermosphere region meteor radar mesospheric winds tides

Effects of mesoscale gravity waves on sporadic E simulated by a one-dimensional dynamic model

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Earth and Planetary Physics 2025年第1期9卷 1-9页

作者： Xu Zhou ZeZhong Li XinAn Yue LiBo Liu key laboratory of Earth and Planetary Physics/Heilongjiang Mohe National Geophysical Observatory/Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences(CAS)Beijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Comparative Planetology/CAS key laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively *** this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high *** by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower *** effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the *** mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their *** addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.

关键词： sporadic E ion tidal layer gravity waves numerical simulation

Proper orthogonal decomposition based seismic source wavefield reconstruction for finite element reverse time migration

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Petroleum Science 2023年第1期20卷 199-211页

作者： Wen-Zhuo Tan Bang-Yu Wu Rui Li Bo Li School of Mathematics and Statistics Xi'an Jiaotong UniversityXi'anShaanxi710049China School of Mathematics and Statistics Shaanxi Normal UniversityXi'anShaanxi710062China snopec key laboratory of geophysics NanjingJiangsu211103China

The large storage requirement is a critical issue in cross-correlation imaging-condition based reverse time migration(RTM),because it requires the operation of the source and receiver wavefields at the same *** boundary value method(BVM),based on the finite difference method(FDM),can be used to reconstruct the source wavefield in the reverse time propagation in the same way as the receiver wavefield,which can reduce the storage burden of the RTM *** that the FDM cannot well handle models with discontinuous material properties and rough interfaces,we develop a source wavefield reconstruction strategy based on the finite element method(FEM),using proper orthogonal decomposition(POD)to enhance computational *** this method,we divide the whole time period into several segments,and construct the POD basis functions to get a reduced order model(ROM)for the source wavefield reconstruction in each *** show the corresponding quantitative analysis of the storage requirement of the *** tests on the homogeneous model show the effectiveness of the proposed method,while the layered model and part of the Marmousi model tests indicate that the POD-FEM can keep an excellent balance between computational efficiency and memory usage compared with the full-stored method(FSM)and the BVM,and can be effectively applied in imaging.

关键词： Reverse time migration Seismic wavefield reconstruction Finite element modeling Proper orthogonal decomposition

Prediction and Elimination of Multiples Based on Energy Flux Conservation Theorem and Prediction Operator Equation

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Chinese Physics Letters 2010年第5期27卷 271-274页

作者：何利刘洪丁仁伟李博 key laboratory of Petroleum geophysics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029

The received wave field including primaries and all of the multiples can be associated with the reflection coefficients which are only primaries by a prediction operator and two equations： the energy flux conservation equation and the prediction operator equation that is developed from the Levinson recursion and can be easily solved by Li group method under a two-dimensional condition. Given reflection coefficients, the prediction operator can be obtained by solving the prediction operator equation. By the energy flux conservation equation, the reciprocal of the prediction operator times the conjugate of it, the wave field can be predicted, in which both of the surface multiples and the internal multiples are involved. On the other hand, if the wave field is given, based on the energy flux conservation equation solved by the 2D spectral factorization, a fully automated data-driven algorithm is developed to remove the surface multiples as well as the internal multiples.

关键词： PREDICTION models ELIMINATION (Mathematics) ENERGY conservation OPERATOR equations RECURSION theory SPECTRAL theory (Mathematics) FACTORIZATION (Mathematics)

Determining the key conditions for the formation of metamorphic core complexes by geodynamic modeling and insights into the destruction of North China Craton

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Science China Earth Sciences 2016年第9期59卷 1873-1884页

作者： LU Gang ZHAO Liang ZHENG TianYu WANG Kun YANG JianFeng State key laboratory of Lithospheric Evolution of Geology and geophysics Chinese Academy of Sciences

Metamorphic core complex(MCC) is characterized by the exhumation of lower crust over a large-scale detachment fault, providing natural records for tectonic extension. MCCs are widely identified in the North China Craton(NCC), which have been intensively studied on their structural and geological characteristics. Yet, the condition for the formation of MCCs and their link with NCC destruction are still in debate. In this study, we perform numerical simulations to investigate MCC formation under extension, with a focus on the effect of crustal rheologies. Results indicate that three end-member modes of deformation may occur: the metamorphic core complex mode, the detachment fault-uplifting mode and the pure shear mode. Weaker lower crust and stronger upper crust may promote the formation of MCC. In contrast, stronger lower crust(>1.3×1021 Pa s) may prohibit the exhumation of lower crust(detachment fault-uplifting mode), while weaker upper crust(<7.8×1021 Pa s) may fail to develop detachment faults(pure shear mode). Given that cratons typically have a strong crust, we suggest that the lower crust of NCC was weakened prior to extension, which promoted the formation of MCC in a later stage under the back-arc extension.

关键词： Metamorphic core complex Numerical modeling North China Craton Extension

A subduction channel model for exhumation of oceanic-type high-pressure to ultrahigh-pressure eclogite-facies metamorphic rocks in SW Tianshan,China

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Science China Earth Sciences 2016年第12期59卷 2339-2354页

作者： LI JiLei GAO Jun WANG XinShui key laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences

High-pressure(HP) and ultrahigh-pressure(UHP) eclogites exposed in collisional orogens are widely regarded to record the history of crustal rocks that were subducted to mantle depths and exhumed back to the *** into subduction and exhumation processes plays an important role in understanding the nature and evolution of subduction zones,geodynamics and plate *** contrast to continental-type HP to UHP metamorphic rocks that are dominated by felsic lithology,oceanic-type HP to UHP metamorphic rocks are dominated by mafic eclogites and thus have greater density,and their exhumation needs to overcome large barriers and may involve complicated tectonic *** exhumation of HP to UHP rocks is mainly influenced by the internal buoyancy,however,the external tectonic forces(such as channel flow) also act as effective exhumation drivers;in addition,effects of tectonic settings(such as slab rollback and breakoff) should take into *** HP-UHP metamorphic terrane in Southwestern Tianshan,which mainly comprises of metasediments with interlayered metamafic lenses and blocks,represents a typical accretionary melange associated with deep subduction of oceanic ***,the exhumation mechanisms of these once deeply buried HP-UHP rocks are still under *** on the field occurrences,petrographic features,peak metamorphic P-T conditions and ages of the eclogites/blueschists and their metasedimentary country rocks,a "sediment-type subduction channel" model is advocated in this study to appraise/decipher the formation and evolution of Southwestern Tianshan HP-UHP metamorphic ***-cyclic metamorphic eclogites record the multistage burial-exhumation cycling manipulated by convective flow in a channel-like interface between the plates,giving robust evidence for the presence of a subduction *** addition,this study summarizes some remaining geotectonic problems and research perspectives concerning the Southwestern Tianshan HP-UHP me

关键词： Eclogite High-pressure metamorphism Oceanic crust Exhumation Subduction channel Southwestern Tianshan

Influence of mantle convection to the crustal movement pattern in the northeastern margin of the Tibetan Plateau based on numerical simulation

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Science China Earth Sciences 2018年第11期61卷 1644-1658页

作者： Aiyu ZHU Dongning ZHANG Tao ZHU Yingxing GUO Institute of geophysics China Earthquake Administration key laboratory of Seismic Observation and Geophysical Imaging Institute of GeophysicsChina Earthquake Administration

Based on the recent observations about the movement and rheological structure of the lithosphere and deformation pattern of the crust, we developed a three-dimensional finite element model for the northeastern margin of the Tibetan *** model considered the impacts of both external and internal conditions, including mantle convection, gravitational potential energy and block interactions. We compared the simulated surface movement rates to the observed GPS velocities, and the results revealed that crustal movement gradually decreased toward the edge of the plateau. The factors controlling this pattern are the interactions of adjacent blocks, gravitational potential energy of the plateau, and also mantle convection as well. Additionally,according to the observation that there was an apparent difference between the horizontal movement rate of the lithosphere and convective velocity of the underlying mantle, and also based on the results of seismic anisotropy studies that suggest different strengths and deformation regimes of the lithosphere in different tectonic blocks, we proposed that the impact of mantle convection on the lithosphere may have varied in space, and introduced a parameter named mantle convection intensity factor in numerical simulations. Our simulation results show consistent surface movement rates with GPS observations, which further supports the viewpoint of seismic anisotropy studies, i.e., the degree of coupling between the crust and mantle varies significantly among different blocks.

关键词： Northeastern margin of the Tibetan Plateau Crustal movement Mantle convection Numerical simulation

Major Advances in the Study of the Precambrian Geology and Metallogenesis of the North China Craton:A Review

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Acta Geologica Sinica(English Edition) 2016年第4期90卷 1122-1155页

作者： ZHAO Lei ZHU Xiyan ZHAI Mingguo State key laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Science key laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences

The North China Craton （NCC） is one of the most ancient cratons in the world and records a complex geological evolution since the early Precambrian. In addition to recording major geological events similar to those of other cratons, the NCC also exhibits some unique features such as multi- stage cratonization （late Archaean and Palaeoproterozoic） and long-term rifting during the Meso- Neoproterozoic. The NCC thus provides one of the best examples to address secular changes in geological history and metallogenic epochs in the evolving Earth. We summarize the major geological events and metallogenic systems of the NCC, so that the evolutionary patterns of the NCC can provide a better understanding of the Precambrian NCC and facilitate comparison of the NCC with other ancient continental blocks globally. The NCC experienced three major tectonic cycles during the Precambrian：（1） Neoarchaean crustal growth and stabilization; （2） Palaeoproterozoic rifting-subduction-accretion-collision with imprints of the Great Oxidation Event and （3） Meso-Neoproterozoic multi-stage rifting. A transition from primitive- to modern-style plate tectonics occurred during the early Precambrian to late Proterozoic and is evidenced by the major geological events. Accompanying these major geological events, three major metallogenic systems are identified：（1） the Archaean banded iron formation system; （2） Palaeoproterozoic Cu-Pb-Zn and Mg-B systems and （3） a Mesoproterozoic rare earth element-Fe- Pb-Zn system. The ore-deposit types in each of these metallogenic systems show distinct characteristics and tectonic affinities.

关键词： North China Craton geological events metallogenesis cratonization multi-stage rifting

Contributions of non-tectonic micro-fractures to hydraulic fracturing—A numerical investigation based on FSD model

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Science China Earth Sciences 2016年第4期59卷 851-865页

作者： WANG Yu Li Xiao ZHAO ZhiHeng ZHOU RunQing ZHANG Bo LI GuanFang key laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences

Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- fractures in the producing shales. The non-tectonic micro-fractures are different from tectonic fractures and are characterized by being irregular, curved, discontinuous, and randomly distributed. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. Two-dimensional computational modeling studies have been used in an initial attempt toward understanding how naturally random fractured reservoirs respond during hydraulic fracturing. The aim of the paper is to investigate the effect of random non-tectonic fractures on hydraulic fracturing. The numerical models with random non-tectonic micro-fractures are built by extracting the fractures of rock blocks after repeated heating and cooling, using a digital image process. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of random fractures;(3) cohesion of random fractures;(4) operational variables such as injection rate; and(5) variable injection rate technology. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in a natural fracture system. Three types of fracturing networks were observed from the studied simulations, and the results also show that variable injection rate technology is most promising for producing complex fracturing networks. This work strongly links the production technology and geomechanical evaluation. It can aid in the understanding and optimization of hydraulic fracturing simulations in naturally random fractured reservoirs.

关键词： Non-tectonic micro-fracture Hydraulic fracturing Fracturing network Numerical simulation