Measurements from geomagnetic satellites continue to underpin advances in geomagnetic field models that describe Earth's internally generated magnetic field.Here,we present a new field model,MSCM,that integrates v...Measurements from geomagnetic satellites continue to underpin advances in geomagnetic field models that describe Earth's internally generated magnetic field.Here,we present a new field model,MSCM,that integrates vector and scalar data from the Swarm,China Seismo-Electromagnetic Satellite(CSES),and Macao Science Satellite-1(MSS-1)missions.The model spans from 2014.0 to 2024.5,incorporating the core,lithospheric,and magnetospheric fields,and it shows characteristics similar to other published models based on different data.For the first time,we demonstrate that it is possible to successfully construct a geomagnetic field model that incorporates CSES vector data,albeit one in which the radial and azimuthal CSES vector components are Huber downweighted.We further show that data from the MSS-1 can be integrated within an explicitly smoothed,fully time-dependent model description.Using the MSCM,we identify new behavior of the South Atlantic Anomaly,the broad region of low magnetic field intensity over the southern Atlantic.This prominent feature appears split into a western part and an eastern part,each with its own intensity minimum.Since 2015,the principal western minimum has undergone only modest intensity decreases of 290 nT and westward motion of 20 km per year,whereas the recently formed eastern minimum has shown a 2–3 times greater intensity drop of 730 nT with no apparent east-west motion.展开更多
Accurate modeling of Earth's ionospheric F-region currents is essential for refining geomagnetic field models and understanding magnetosphere-ionosphere coupling.In this study,we develop averaged models to charact...Accurate modeling of Earth's ionospheric F-region currents is essential for refining geomagnetic field models and understanding magnetosphere-ionosphere coupling.In this study,we develop averaged models to characterize F-region currents using magnetic data from the MSS-1(Macao Science Satellite-1) and Swarm satellite missions.Our approach employs a toroidal field representation,utilizing spherical harmonics to capture spatial variations and Fourier series to represent temporal dynamics.Two models,Model-A and Model-B,derived from distinct datasets,are constructed to represent current patterns at altitudes of 450 km and 512 km,respectively.Our models successfully capture the primary spatial structures and seasonal variations of polar field-aligned currents.Additionally,they accurately reproduce the localized inter-hemispheric field-aligned currents observed in mid and low latitudes during solstices,particularly between 14:00 and 16:00 magnetic local times.These findings enhance our understanding of ionospheric F-region currents and contribute to more precise geomagnetic field modeling.展开更多
The Macao satellites differ from their predecessors in their orbits:MSS-1(Macao Science Satellite-1)is in low inclination and the planned MSS-2 will be in highly elliptical orbits.This paper reviews the fundamental ad...The Macao satellites differ from their predecessors in their orbits:MSS-1(Macao Science Satellite-1)is in low inclination and the planned MSS-2 will be in highly elliptical orbits.This paper reviews the fundamental advantages and disadvantages of the different possible magnetic measurements:the component(declination,intensity,etc.)and location(satellite,ground,etc.).When planning a survey the choice of component is the"What?"question;the choice of location the"Where?"question.Results from potential theory inform the choice of measurement and data analysis.For example,knowing the vertical component of magnetic field provides a solution for the full magnetic field everywhere in the potential region.This is the familiar Neumann problem.In reality this ideal dataset is never available.In the past we were restricted to declination data only,then direction only,then total intensity only.There have also been large swathes of Earth's surface with no measurements at all(MSS-1 is restricted to latitudes below).These incomplete datasets throw up new questions for potential theory,questions that have some intriguing answers.When only declination is known uniqueness is provided by horizontal intensity measurements on a single line joining the dip-poles.When only directions are involved uniqueness is provided by a single intensity measurement,at least in principle.Paleomagnetic intensities can help.When only total intensity is known,as was largely the case in the early satellite era,uniqueness is provided by a precise location of the magnetic equator.Holes in the data distribution is a familiar problem in geophysical studies.All magnetic measurements sample,to a greater or lesser extent,the potential field everywhere.There is a trade-off between measurements close to the source,good for small targets and high resolution,and the broader sample of a distant measurement.The sampling of a measurement is given by the appropriate Green's function of the Laplacian,which determines both the resolution and scope of the measurement.For example,radial and horizontal measurements near the Earth's surface give a weighted average of the radial component over a patch of the core surface beneath the measurement site about in radius.The patch is smaller for shallower surfaces,for example from satellite to ground.Holes in the data distribution do not correspond to similar holes at the source surface;the price paid is in resolution of the source.I argue that,in the past,we have been too reluctant to take advantage of incomplete and apparently hopeless datasets.展开更多
The scientific research of geomagnetism has been largely driven by new geomagnetic data that are available to scientists.Macao Science Satellite-1(MSS-1)was successfully launched on 21st May 2023 into a near-circular ...The scientific research of geomagnetism has been largely driven by new geomagnetic data that are available to scientists.Macao Science Satellite-1(MSS-1)was successfully launched on 21st May 2023 into a near-circular orbit of altitude of about 450 km with a low inclination of 41°.After careful evaluation and calibration(7^(th)June 2023 to 31^(st)July 2024),the data of MSS-1 were released to the international scientific community on 1 August 2024,providing the highly accurate data of global geomagnetic field with an unprecedented local-time coverage to the community.This special issue of Initial Scientific Results of MSS-1,primarily driven by the new MSS-1 data,contains 27 research articles ranging from the MSS-1 design,satellite data analysis,outer core dynamics,mantle induction,lithospheric field modeling,ocean induced magnetic field,ionosphere and magnetosphere currents,to solar activities.展开更多
The MSS-1 satellite began mapping Earth's magnetic field in November 2023.Here,we perform a preliminary assessment of the new information provided on Earth's lithospheric magnetic field from the first 12 month...The MSS-1 satellite began mapping Earth's magnetic field in November 2023.Here,we perform a preliminary assessment of the new information provided on Earth's lithospheric magnetic field from the first 12 months of data from MSS-1.We analyze data from the low-inclination orbital tracks of MSS-1 alongside data collected contemporaneously by the Swarm mission,and compare these to models for the lithospheric field from older satellite data and to predictions from models of lithospheric magnetization from tectonic constraints.We find that 1 year of data grouped into geographical bins is sufficient to produce a robust map of lithospheric anomalies.Time series analysis reveals that bins further from the equator arrive at stable values more rapidly,while equatorial regions require 9-10months of data accumulation for stable signal recovery.The mapped data agree well with older satellite models and with predictions from a lithospheric magnetization model,with the largest mismatches suggesting that models of continental magnetization in particular require further revision.These results demonstrate the value of MSS-1's unique orbital configuration in complementing existing satellite magnetic field measurements.展开更多
Earth’s internal core and crustal magnetic fields,as measured by geomagnetic satellites like MSS-1(Macao Science Satellite-1)and Swarm,are vital for understanding core dynamics and tectonic evolution.To model these i...Earth’s internal core and crustal magnetic fields,as measured by geomagnetic satellites like MSS-1(Macao Science Satellite-1)and Swarm,are vital for understanding core dynamics and tectonic evolution.To model these internal magnetic fields accurately,data selection based on specific criteria is often employed to minimize the influence of rapidly changing current systems in the ionosphere and magnetosphere.However,the quantitative impact of various data selection criteria on internal geomagnetic field modeling is not well understood.This study aims to address this issue and provide a reference for constructing and applying geomagnetic field models.First,we collect the latest MSS-1 and Swarm satellite magnetic data and summarize widely used data selection criteria in geomagnetic field modeling.Second,we briefly describe the method to co-estimate the core,crustal,and large-scale magnetospheric fields using satellite magnetic data.Finally,we conduct a series of field modeling experiments with different data selection criteria to quantitatively estimate their influence.Our numerical experiments confirm that without selecting data from dark regions and geomagnetically quiet times,the resulting internal field differences at the Earth’s surface can range from tens to hundreds of nanotesla(nT).Additionally,we find that the uncertainties introduced into field models by different data selection criteria are significantly larger than the measurement accuracy of modern geomagnetic satellites.These uncertainties should be considered when utilizing constructed magnetic field models for scientific research and applications.展开更多
The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic...The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic field has not been previously estimated or incorporated into geomagnetic field models,potentially causing leakage into the core field model.Here,we present a method to account for the circulation-induced magnetic field during geomagnetic field modeling.First,a forward model of the circulation-induced magnetic field is constructed by numerically solving electromagnetic induction equations based on a realistic ocean circulation model.Then,this forward model is subtracted from the observed data.Finally,the core and lithospheric fields,magnetospheric and Earth’s mantle-induced fields,and the ocean tide-induced magnetic field are co-estimated.Applying our method to over 20 years of MSS-1,Swarm,CryoSat-2,and CHAMP satellite magnetic data,we derive a new multisource geomagnetic field model(MGFM).We find that incorporating a forward model of the circulation-induced magnetic field marginally improves the fit to the data.Furthermore,we demonstrate that neglecting the circulation-induced magnetic field in geomagnetic field modeling results in leakage into the core field model.The highlights of the MGFM model include:(i)a good agreement with the widely used CHAOS model series;(ii)the incorporation of magnetic fields induced by both ocean tides and circulation;and(iii)the suppression of leakage of the circulation-induced magnetic field into the core field model.展开更多
This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar...This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar-orbiting(Swarm)and low-inclination(MSS-1)satellites in geomagnetic modelling and monitoring large-scale magnetospheric contributions.Data from close encounters between MSS-1 and Swarm(intersatellite distance<100 km)confirm the excellent data quality of the two satellite missions(<1 nT median difference in scalar intensity F)and allow for data calibration and validation and investigations of in-situ ionospheric currents.The reason for a small but consistent difference(F as measured by MSS-1 is 0.5 to 1.0 nT larger than that measured by Swarm)is unknown.Combining MSS-1’s low-inclination data with Swarm’s near-polar observations significantly enhances the spatial-temporal resolution of Earth’s magnetic field models,allowing for new opportunities for studying both rapid core field variations at low latitudes and the local-time dependence of large-scale magnetospheric current systems.A joint analysis of magnetic data from six satellites during the May 2024 geomagnetic storm reveals a clear dawn-dusk asymmetry,with equatorial magnetic disturbances during dusk being approximately 150 nT more negative than during dawn.展开更多
Geomagnetic observatory data are crucial for all branches of geophysics because they can contribute to earthquake research by detecting anomalies in the Earth’s magnetic field.Recently,data records from the Misallat(...Geomagnetic observatory data are crucial for all branches of geophysics because they can contribute to earthquake research by detecting anomalies in the Earth’s magnetic field.Recently,data records from the Misallat(MLT)and Abu Simbel(ABS)Egyptian geomagnetic observatories were processed and found to be of good quality.In this study,Egyptian observatory data were tested during both quiet and disturbed events and compared with data from INTERMAGNET observatories worldwide at different latitudes and within a narrow range of longitudes in both hemispheres.This study investigated the relationships between magnetic field components from Egyptian observatories and those from INTERMAGNET observatories using graphical representations of the X components;Pearson’s correlation for the X,Y,Z,and F components;cross-correlation for the X component;and wavelet coherence for the F component.The results of this study showed a high correlation between Egyptian observatories and all utilized INTERMAGNET stations,except those located at high latitudes,during both quiet and disturbed events.Additionally,the study confirmed the observed consistency between Egyptian observatories and selected INTERMAGNET stations.Therefore,Egyptian observatories can feasibly fill the gap in the Middle East and North Africa.展开更多
The Macao Science Satellite-1(MSS-1)is the first space science satellite jointly developed on the Chinese mainland and in Macao region.It comprises two satellites,named MSS-1A and MSS-1B,and holds considerable importa...The Macao Science Satellite-1(MSS-1)is the first space science satellite jointly developed on the Chinese mainland and in Macao region.It comprises two satellites,named MSS-1A and MSS-1B,and holds considerable importance in China’s space exploration endeavors.Among these,MSS-1A is the world’s first high-precision scientific satellite dedicated to exploring the geomagnetic field and space environment at low latitudes.Equipped with two high-precision vector magnetometers and one scalar magnetometer,which are integrally installed on a highly stable nonmagnetic optical bench,the MSS-1A enables simultaneous high-precision measurements of both the Earth’s vector magnetic field and its scalar components.Its design integrates several state-of-the-art technologies,including arc-second-level thermal stability control,nonmagnetic thermal control for the optical bench,and ultra-high magnetic cleanliness control.These innovations effectively minimize magnetic interference originating from the satellite itself,thereby substantially improving the precision of geomagnetic field measurements and establishing a robust technical foundation for future magnetic survey satellite constellations.展开更多
The Sq(solar quiet)geomagnetic field is generated by the electric currents in the E-region of the ionosphere,driven by the atmospheric tides.It is a critical part of high-precision geomagnetic field modeling.Based on ...The Sq(solar quiet)geomagnetic field is generated by the electric currents in the E-region of the ionosphere,driven by the atmospheric tides.It is a critical part of high-precision geomagnetic field modeling.Based on the classic thermal tide theory and atmospheric electrodynamics,this research,for the first time,developed an Sq geomagnetic field model that is directly built on the physical mechanism of the ionospheric dynamo,which is responsible for daily variations of the geomagnetic field.The performance in Sq geomagnetic field modeling was investigated using the Macao Science Satellite-1(MSS-1)data.Our model can enhance the physics-based framework of comprehensive geomagnetic field modeling for the MSS-1 and ensuing missions.展开更多
High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science ...High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science Satellite-1A (MSS-1A),added to data from other space-based magnetometers,should increase significantly the ability of scientists to observe changes in Earth’s magnetic field over time and space.Additionally,the MSS-1A’s FGM is intended to help identify magnetic disturbances affecting the spacecraft itself.This report focuses on the in-flight calibration of the MSS-1 FGM.A scalar calibration,independent of geomagnetic field models,was performed to correct offsets,sensitivities,and misalignment angles of the FGM.Using seven months of data,we find that the in-flight calibration parameters show good stability.We determined Euler angles describing the rotational relationship between the FGM and the Advanced Stellar Compass (ASC) coordinate system using two approaches:calibration with the CHAOS-7 geomagnetic field model,and simultaneous estimation of Euler angles and Gaussian spherical harmonic coefficients through self-consistent modeling.The accuracy of Euler angles describing the rotation was better than 18 arcsec.The calibrated FGM data exhibit good agreement with the calibrated data of the Vector Field Magnetometer (VFM),which is the primary vector magnetometer of the satellite.These calibration efforts have significantly improved the accuracy of the FGM measurements,which are now providing reliable data for geomagnetic field studies that promise to advance our understanding of the Earth’s magnetic environment.展开更多
Strong flares and/or coronal mass ejections(CMEs) could bring us disastrous space weather,destroy crucial technology in space,and cause a large-scale blackout during some extreme cases.They frequently cause geomagneti...Strong flares and/or coronal mass ejections(CMEs) could bring us disastrous space weather,destroy crucial technology in space,and cause a large-scale blackout during some extreme cases.They frequently cause geomagnetic storms,which is a sudden disturbance of the Earth's magnetosphere.It is well accepted that CMEs play a dominant role in causing geomagnetic storms by a direct impact,but it is still not very clear regarding their association with solar flares.The association would be helpful for forecasting geomagnetic storms directly from flares,which are much easier to observe.The Macao Science Satellite-1(MSS-1) mission,with the scientific aim of studying the origin and evolution of the geomagnetic field,is able to accurately measure the vector geomagnetic field.Besides,it measures rapid spectral evolution of the solar X-ray irradiance of solar flares.In this study,we analyzed measurements by MSS-1 during a series of X-class flares in October of 2024,and saw the relationship between the flares and the associated geomagnetic storms.The observations support that the major geomagnetic storms tend to be associated with flares' duration in addition to flare class.We also find that long duration ones have radiated more energy in the extreme ultraviolet waveband.Being equally important,our results show that the magnetic fields measured by MSS-1,especially its external(e_(1)^(0)) coefficient,can well be used for monitoring the geomagnetic disturbance.展开更多
This study utilizes radio occultation observations from the Macao Science Satellite-1 mission(MSS-1)to investigate ionospheric response to the May 2024 G5 geomagnetic storm within the South Atlantic Anomaly(SAA)region...This study utilizes radio occultation observations from the Macao Science Satellite-1 mission(MSS-1)to investigate ionospheric response to the May 2024 G5 geomagnetic storm within the South Atlantic Anomaly(SAA)region.The distinctive data from MSS-1,complemented by observations from the ground-based Global Navigation Satellite System(GNSS)and the Constellation Observing System for Meteorology,Ionosphere,and Climate follow-on satellite mission(COSMIC-2),reveal a super plasma fountain effect during the main phase of the storm.This effect was marked by peaks in the equatorial ionization anomaly that extended beyond their typical latitude range.The MSS-1 observations,particularly in the northern hemisphere of the SAA region,confirm the role of prompt penetration electric fields in driving ionospheric disturbances and amplifying scintillation at higher altitudes.The study also identifies a decrease in total electron content and a reduction in scintillation occurrence during the recovery phase of the storm.The results demonstrate the pivotal role that MSS-1 observations can play,when combined with ground-based and COSMIC-2 observations,in providing a more comprehensive understanding of ionospheric response to severe geomagnetic storms.展开更多
Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and Earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on Earth,while al...Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and Earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on Earth,while also deepening our knowledge of stellar physics and solar system dynamics.Determining the solar cycles between 1600 and 1700-especially the post-1645 Maunder Minimum,characterized by significantly reduced solar activity-poses challenges to existing solar activity proxies.This study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to 1700.Remarkably,a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles,diverging from the widely accepted record of 12 cycles during that time.This research enhances our understanding of historical solar activity,and underscores the importance of integrating diverse historical sources into modern analyses.展开更多
The Michelson Interferometer for Global High-resolution Thermospheric Imaging(MIGHTI)onboard the Ionospheric Connection Explorer(ICON)satellite offers the opportunity to investigate the altitude profile of thermospher...The Michelson Interferometer for Global High-resolution Thermospheric Imaging(MIGHTI)onboard the Ionospheric Connection Explorer(ICON)satellite offers the opportunity to investigate the altitude profile of thermospheric winds.In this study,we used the red-line measurements of MIGHTI to compare with the results estimated by Horizontal Wind Model 14(HWM14).The data selected included both the geomagnetic quiet period(December 2019 to August 2022)and the geomagnetic storm on August 26-28,2021.During the geomagnetic quiet period,the estimations of neutral winds from HWM14 showed relatively good agreement with the observations from ICON.According to the ICON observations,near the equator,zonal winds reverse from westward to eastward at around 06:00 local time(LT)at higher altitudes,and the stronger westward winds appear at later LTs at lower altitudes.At around 16:00 LT,eastward winds at 300 km reverse to westward,and vertical gradients of zonal winds similar to those at sunrise hours can be observed.In the middle latitudes,zonal winds reverse about 2-4 h earlier.Meridional winds vary more significantly than zonal winds with seasonal and latitudinal variations.According to the ICON observations,in the northern low latitudes,vertical reversals of meridional winds are found at 08:00-13:00 LT from 300 to 160 km and at around 18:00 LT from 300 to 200 km during the June solstice.Similar reversals of meridional winds are found at 04:00-07:00 LT from 300 to 160 km and at 22:00-02:00 LT from 270 to 200 km during the December solstice.In the southern low latitudes,meridional wind reversals occur at 08:00-11:00 LT from 200 to 160 km and at 21:00-02:00 LT from 300 to 200 km during the June solstice.During the December solstice,reversals of the meridional wind appear at 20:00-01:00 LT below 200 km and at 06:00-11:00 LT from 300 to 160 km.In the northern middle latitudes,the northward winds are dominant at 08:00-14:00 LT at 230 km during the June solstice.Northward winds persist until 16:00 LT at 160 and 300 km.During the December solstice,the northward winds are dominant from 06:00 to 21:00 LT.The vertical variations in neutral winds during the geomagnetic storm on August 26-28 were analyzed in detail.Both meridional and zonal winds during the active geomagnetic period observed by ICON show distinguishable vertical shear structures at different stages of the storm.On the dayside,during the main phase,the peak velocities of westward winds extend from a higher altitude to a lower altitude,whereas during the recovery phase,the peak velocities of the westward winds extend from lower altitudes to higher altitudes.The velocities of the southward winds are stronger at lower altitudes during the storm.These vertical structures of horizontal winds during the storm could not be reproduced by the HWM14 wind estimations,and the overall response to the storm of the horizontal winds in the low and middle latitudes is underestimated by HWM14.The ICON observations provide a good dataset for improving the HWM wind estimations in the middle and upper atmosphere,especially the vertical variations.展开更多
The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constella...The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constellation data from the Chinese Seismo-Electromagnet Satellite(CSES)and Swarm satellites to extract the SV in China and surrounding areas,based on the Geomagnetic Virtual Observatory(GVO)method.On this basis,we have developed two GVO products:the core field,and the SV series.The accuracies of these products are assessed using ground observatories measurements and geomagnetic field model.Moreover,the results indicate that the GVO products align well with the series from ground observatories and the CHAOS model.The majority of root-mean-square deviation(RMSE)values of the core field series are less than 5 nT,consistent with the INTERMAGNET standards for quasi-definitive data.In the GVO core field series,the maximum accuracy of one-month and four-month intervals are 2.24 nT and 1.16 nT,respectively.In the GVO SV series,the maximum accuracy of one-month and four-month intervals are 2.03 nT/yr and 1.36 nT/yr,respectively.The GVO SV series effectively capture geomagnetic jerks without losing temporal resolution comparing with the recording of ground observatories.We demonstrate that the GVO method serves as an effective and precise tool for extracting SV information of geomagnetic fields.In the GVO products,the RMSE of the horizontal component exceeds that of the vertical component,and the magnitude of RMSE deviation correlates with solar activity levels.With more and more geomagnetic satellites in orbit,we wish to use multi-constellation magnetic satellite data to assess the geomagnetic field more accurately.展开更多
The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized ...The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized lithosphere,and the space current systems.Modeling of the lithospheric contribution plays an important role in the geophysical studies and industrial applications.In this paper,we propose a new method for global and regional modeling of the lithospheric magnetic field based on the cubed-sphere.An equivalent dipole source method on a quasi-uniform cubed-sphere grid is employed in the forward modeling.The dipole directions are fixed according to a priori magnetization and the relative intensities are estimated by an inversion procedure of least-squares fitting with minimum model regularization.Several numerical tests are performed to validate the accuracy and efficiency of both forward modeling and inversion procedure.The proposed method is applied to the global and regional modeling based on the latest magnetic data from Swarm Alpha satellite and MSS-1 mission.The model results indicate that the proposed method works quite well for realistic satellite data and MSS-1 data is consistent with the Swarm data in terms of lithospheric field modeling.展开更多
The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the North...The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the Northwestern Himalaya,using advanced geomagnetic techniques for delineation.Geomagnetic measurements reveal the characteristics of the newly identified Gulmarg fault.Ground magnetic surveys with Proton Precession Magnetometers along linear profiles and a magnetic grid highlight fault-related anomalies.The results indicate a fault running through the Gulmarg meadows,approximately 1.6 km from the Balapur fault,suggesting a potential coupling between the two.Three profiles across the fault exhibit distinctive magnetic variations,highlighting the intricate nature of the fault structure.Gridding methods also reveal anomalies associated with subsurface water and hydraulic activities,underscoring the importance of advanced geophysical techniques.This study emphasizes the significance of detailed investigations to unravel the complex geological processes shaping the Kashmir Basin.The study provides valuable insights into the tectonic activity in the Gulmarg region,underscoring the role of geophysical studies in enhancing our understanding of dynamic geological structures like the Gulmarg fault zone.展开更多
Ionospheric scintillation refers to rapid radio signal amplitude and phase fluctuations due to small-scale irregularities in the ionosphere.Occurring primarily at equatorial and low latitudes,scintillation is linked t...Ionospheric scintillation refers to rapid radio signal amplitude and phase fluctuations due to small-scale irregularities in the ionosphere.Occurring primarily at equatorial and low latitudes,scintillation is linked to equatorial plasma bubbles(EPBs),regions of depleted plasma density that form after sunset.Ionospheric scintillation typically occurs from post-sunset hours until midnight.Post-sunset EPBs can be enhanced or suppressed during geomagnetic storms,depending on local sunset timing and how it relates to the storm's main or recovery phases.This study analyzes ionospheric scintillation in Indonesia,located at low geomagnetic and geographic latitudes,during geomagnetic events from 2003 to 2024.Using the S4 index,scintillation was examined with data from seven observation stations during geomagnetic storm events.Geomagnetic activity was evaluated using Dst,SYM-H,and AE indices,employing Superposed Epoch Analysis(SEA)to assess scintillation occurrence linked to minimum SYM-H,defined as epoch 0 to represent the storm peak or the onset of recovery phase in each event.The analysis categorized geomagnetic storms into weak-moderate(–100 nT<min.Dst≤–30 nT)and strong(min.Dst≤–100 nT),and examined their dependence on the local time of minimum SYM-H.Results indicate that scintillation first appears~6 hours after epoch 0 in weak-moderate geomagnetic storms,and~12 hours after epoch 0 in strong geomagnetic storms.The average AE index returns to its baseline value(quiet condition)~6 and~12 hours after epoch 0 for weak-moderate and strong geomagnetic storms,respectively.Further analysis based on the classification of the local time of epoch 0 shows that scintillation occurrence is not observed in post-sunset hours when epoch 0 falls between 16:00 and 19:00 LT for weak-moderate geomagnetic storms.In strong geomagnetic storms,scintillation occurrence during post-sunset hours is absent when epoch 0 is between 10:00 and 19:00 LT.Notably,when the minimum SYM-H(epoch 0)nearly coincides with local sunset,scintillation activity occurs around sunset in both weak-moderate and strong geomagnetic storms.Furthermore,when epoch 0 falls within midnight until early morning,scintillation can be generated in the post-sunset hours before epoch 0.Still,post-midnight scintillation is not observed in the equatorial region during the recovery phase of either weak-moderate and strong storm events.Our findings show that when sunset falls before or coincide with epoch 0,the likelihood of post-sunset EPB and scintillation increases,due to the prompt-penetration electric field(PPEF)in the main phase of storm.The disturbance dynamo electric field(DDEF)in the recovery phase driven by equatorward winds from auroral Joule heating operates for at least 6-and 12-hours post-epoch 0 in the cases of weak-moderate and strong geomagnetic storms,respectively.When the local sunset falls within these operational DDEF periods,post-sunset EPBs will likely be suppressed,inhibiting ionospheric scintillation during post-sunset hours.Finally,this study provides essential information for developing more accurate ionospheric scintillation prediction models in space weather services in equatorial regions.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42274003)PWL was supported by Swarm DISC(Swarm Data,Innovation,and Science Cluster)+2 种基金funded by the European Space Agency(ESAContract No.4000109587)HFR acknowledges funding from the UK Natural Environment Research Council(Grant No.NE/V010867/1)。
文摘Measurements from geomagnetic satellites continue to underpin advances in geomagnetic field models that describe Earth's internally generated magnetic field.Here,we present a new field model,MSCM,that integrates vector and scalar data from the Swarm,China Seismo-Electromagnetic Satellite(CSES),and Macao Science Satellite-1(MSS-1)missions.The model spans from 2014.0 to 2024.5,incorporating the core,lithospheric,and magnetospheric fields,and it shows characteristics similar to other published models based on different data.For the first time,we demonstrate that it is possible to successfully construct a geomagnetic field model that incorporates CSES vector data,albeit one in which the radial and azimuthal CSES vector components are Huber downweighted.We further show that data from the MSS-1 can be integrated within an explicitly smoothed,fully time-dependent model description.Using the MSCM,we identify new behavior of the South Atlantic Anomaly,the broad region of low magnetic field intensity over the southern Atlantic.This prominent feature appears split into a western part and an eastern part,each with its own intensity minimum.Since 2015,the principal western minimum has undergone only modest intensity decreases of 290 nT and westward motion of 20 km per year,whereas the recently formed eastern minimum has shown a 2–3 times greater intensity drop of 730 nT with no apparent east-west motion.
基金supported by the National Natural Science Foundation of China (42250101)the Macao Foundation. The computation made use of the high-performance computing resources at the center of the MSS data processing and analysis。
文摘Accurate modeling of Earth's ionospheric F-region currents is essential for refining geomagnetic field models and understanding magnetosphere-ionosphere coupling.In this study,we develop averaged models to characterize F-region currents using magnetic data from the MSS-1(Macao Science Satellite-1) and Swarm satellite missions.Our approach employs a toroidal field representation,utilizing spherical harmonics to capture spatial variations and Fourier series to represent temporal dynamics.Two models,Model-A and Model-B,derived from distinct datasets,are constructed to represent current patterns at altitudes of 450 km and 512 km,respectively.Our models successfully capture the primary spatial structures and seasonal variations of polar field-aligned currents.Additionally,they accurately reproduce the localized inter-hemispheric field-aligned currents observed in mid and low latitudes during solstices,particularly between 14:00 and 16:00 magnetic local times.These findings enhance our understanding of ionospheric F-region currents and contribute to more precise geomagnetic field modeling.
文摘The Macao satellites differ from their predecessors in their orbits:MSS-1(Macao Science Satellite-1)is in low inclination and the planned MSS-2 will be in highly elliptical orbits.This paper reviews the fundamental advantages and disadvantages of the different possible magnetic measurements:the component(declination,intensity,etc.)and location(satellite,ground,etc.).When planning a survey the choice of component is the"What?"question;the choice of location the"Where?"question.Results from potential theory inform the choice of measurement and data analysis.For example,knowing the vertical component of magnetic field provides a solution for the full magnetic field everywhere in the potential region.This is the familiar Neumann problem.In reality this ideal dataset is never available.In the past we were restricted to declination data only,then direction only,then total intensity only.There have also been large swathes of Earth's surface with no measurements at all(MSS-1 is restricted to latitudes below).These incomplete datasets throw up new questions for potential theory,questions that have some intriguing answers.When only declination is known uniqueness is provided by horizontal intensity measurements on a single line joining the dip-poles.When only directions are involved uniqueness is provided by a single intensity measurement,at least in principle.Paleomagnetic intensities can help.When only total intensity is known,as was largely the case in the early satellite era,uniqueness is provided by a precise location of the magnetic equator.Holes in the data distribution is a familiar problem in geophysical studies.All magnetic measurements sample,to a greater or lesser extent,the potential field everywhere.There is a trade-off between measurements close to the source,good for small targets and high resolution,and the broader sample of a distant measurement.The sampling of a measurement is given by the appropriate Green's function of the Laplacian,which determines both the resolution and scope of the measurement.For example,radial and horizontal measurements near the Earth's surface give a weighted average of the radial component over a patch of the core surface beneath the measurement site about in radius.The patch is smaller for shallower surfaces,for example from satellite to ground.Holes in the data distribution do not correspond to similar holes at the source surface;the price paid is in resolution of the source.I argue that,in the past,we have been too reluctant to take advantage of incomplete and apparently hopeless datasets.
基金supported by the National Natural Science Foundation of China(42250101)the Macao Foundation and China National Space Administration。
文摘The scientific research of geomagnetism has been largely driven by new geomagnetic data that are available to scientists.Macao Science Satellite-1(MSS-1)was successfully launched on 21st May 2023 into a near-circular orbit of altitude of about 450 km with a low inclination of 41°.After careful evaluation and calibration(7^(th)June 2023 to 31^(st)July 2024),the data of MSS-1 were released to the international scientific community on 1 August 2024,providing the highly accurate data of global geomagnetic field with an unprecedented local-time coverage to the community.This special issue of Initial Scientific Results of MSS-1,primarily driven by the new MSS-1 data,contains 27 research articles ranging from the MSS-1 design,satellite data analysis,outer core dynamics,mantle induction,lithospheric field modeling,ocean induced magnetic field,ionosphere and magnetosphere currents,to solar activities.
基金supported by the Australian Research Council (grants DP200100966, FT210100557)supported as part of the Swarm DISC activities,funded by ESA contact no. 4000109587。
文摘The MSS-1 satellite began mapping Earth's magnetic field in November 2023.Here,we perform a preliminary assessment of the new information provided on Earth's lithospheric magnetic field from the first 12 months of data from MSS-1.We analyze data from the low-inclination orbital tracks of MSS-1 alongside data collected contemporaneously by the Swarm mission,and compare these to models for the lithospheric field from older satellite data and to predictions from models of lithospheric magnetization from tectonic constraints.We find that 1 year of data grouped into geographical bins is sufficient to produce a robust map of lithospheric anomalies.Time series analysis reveals that bins further from the equator arrive at stable values more rapidly,while equatorial regions require 9-10months of data accumulation for stable signal recovery.The mapped data agree well with older satellite models and with predictions from a lithospheric magnetization model,with the largest mismatches suggesting that models of continental magnetization in particular require further revision.These results demonstrate the value of MSS-1's unique orbital configuration in complementing existing satellite magnetic field measurements.
基金supported by the National Natural Science Foundation of China(42250101)the Macao Foundation。
文摘Earth’s internal core and crustal magnetic fields,as measured by geomagnetic satellites like MSS-1(Macao Science Satellite-1)and Swarm,are vital for understanding core dynamics and tectonic evolution.To model these internal magnetic fields accurately,data selection based on specific criteria is often employed to minimize the influence of rapidly changing current systems in the ionosphere and magnetosphere.However,the quantitative impact of various data selection criteria on internal geomagnetic field modeling is not well understood.This study aims to address this issue and provide a reference for constructing and applying geomagnetic field models.First,we collect the latest MSS-1 and Swarm satellite magnetic data and summarize widely used data selection criteria in geomagnetic field modeling.Second,we briefly describe the method to co-estimate the core,crustal,and large-scale magnetospheric fields using satellite magnetic data.Finally,we conduct a series of field modeling experiments with different data selection criteria to quantitatively estimate their influence.Our numerical experiments confirm that without selecting data from dark regions and geomagnetically quiet times,the resulting internal field differences at the Earth’s surface can range from tens to hundreds of nanotesla(nT).Additionally,we find that the uncertainties introduced into field models by different data selection criteria are significantly larger than the measurement accuracy of modern geomagnetic satellites.These uncertainties should be considered when utilizing constructed magnetic field models for scientific research and applications.
基金supported by the National Natural Science Foundation of China(42250101,42250102)the Macao Foundation.
文摘The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic field has not been previously estimated or incorporated into geomagnetic field models,potentially causing leakage into the core field model.Here,we present a method to account for the circulation-induced magnetic field during geomagnetic field modeling.First,a forward model of the circulation-induced magnetic field is constructed by numerically solving electromagnetic induction equations based on a realistic ocean circulation model.Then,this forward model is subtracted from the observed data.Finally,the core and lithospheric fields,magnetospheric and Earth’s mantle-induced fields,and the ocean tide-induced magnetic field are co-estimated.Applying our method to over 20 years of MSS-1,Swarm,CryoSat-2,and CHAMP satellite magnetic data,we derive a new multisource geomagnetic field model(MGFM).We find that incorporating a forward model of the circulation-induced magnetic field marginally improves the fit to the data.Furthermore,we demonstrate that neglecting the circulation-induced magnetic field in geomagnetic field modeling results in leakage into the core field model.The highlights of the MGFM model include:(i)a good agreement with the widely used CHAOS model series;(ii)the incorporation of magnetic fields induced by both ocean tides and circulation;and(iii)the suppression of leakage of the circulation-induced magnetic field into the core field model.
基金the China National Space Administration (CNSA) and the Macao Foundation for operating the MSS-1satelliteThis work has been carried out as part of ESA’s Swarm DISC activities funded by ESA contract no.4000109587.
文摘This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar-orbiting(Swarm)and low-inclination(MSS-1)satellites in geomagnetic modelling and monitoring large-scale magnetospheric contributions.Data from close encounters between MSS-1 and Swarm(intersatellite distance<100 km)confirm the excellent data quality of the two satellite missions(<1 nT median difference in scalar intensity F)and allow for data calibration and validation and investigations of in-situ ionospheric currents.The reason for a small but consistent difference(F as measured by MSS-1 is 0.5 to 1.0 nT larger than that measured by Swarm)is unknown.Combining MSS-1’s low-inclination data with Swarm’s near-polar observations significantly enhances the spatial-temporal resolution of Earth’s magnetic field models,allowing for new opportunities for studying both rapid core field variations at low latitudes and the local-time dependence of large-scale magnetospheric current systems.A joint analysis of magnetic data from six satellites during the May 2024 geomagnetic storm reveals a clear dawn-dusk asymmetry,with equatorial magnetic disturbances during dusk being approximately 150 nT more negative than during dawn.
文摘Geomagnetic observatory data are crucial for all branches of geophysics because they can contribute to earthquake research by detecting anomalies in the Earth’s magnetic field.Recently,data records from the Misallat(MLT)and Abu Simbel(ABS)Egyptian geomagnetic observatories were processed and found to be of good quality.In this study,Egyptian observatory data were tested during both quiet and disturbed events and compared with data from INTERMAGNET observatories worldwide at different latitudes and within a narrow range of longitudes in both hemispheres.This study investigated the relationships between magnetic field components from Egyptian observatories and those from INTERMAGNET observatories using graphical representations of the X components;Pearson’s correlation for the X,Y,Z,and F components;cross-correlation for the X component;and wavelet coherence for the F component.The results of this study showed a high correlation between Egyptian observatories and all utilized INTERMAGNET stations,except those located at high latitudes,during both quiet and disturbed events.Additionally,the study confirmed the observed consistency between Egyptian observatories and selected INTERMAGNET stations.Therefore,Egyptian observatories can feasibly fill the gap in the Middle East and North Africa.
文摘The Macao Science Satellite-1(MSS-1)is the first space science satellite jointly developed on the Chinese mainland and in Macao region.It comprises two satellites,named MSS-1A and MSS-1B,and holds considerable importance in China’s space exploration endeavors.Among these,MSS-1A is the world’s first high-precision scientific satellite dedicated to exploring the geomagnetic field and space environment at low latitudes.Equipped with two high-precision vector magnetometers and one scalar magnetometer,which are integrally installed on a highly stable nonmagnetic optical bench,the MSS-1A enables simultaneous high-precision measurements of both the Earth’s vector magnetic field and its scalar components.Its design integrates several state-of-the-art technologies,including arc-second-level thermal stability control,nonmagnetic thermal control for the optical bench,and ultra-high magnetic cleanliness control.These innovations effectively minimize magnetic interference originating from the satellite itself,thereby substantially improving the precision of geomagnetic field measurements and establishing a robust technical foundation for future magnetic survey satellite constellations.
基金supported by the National Natural Science Foundation of China(Grant Nos.12250013,12403070,12425306,42250101,12273092)the Macao Foundation,and Shanghai Post-doctoral Excellence Program(Grant No.2023000137)。
文摘The Sq(solar quiet)geomagnetic field is generated by the electric currents in the E-region of the ionosphere,driven by the atmospheric tides.It is a critical part of high-precision geomagnetic field modeling.Based on the classic thermal tide theory and atmospheric electrodynamics,this research,for the first time,developed an Sq geomagnetic field model that is directly built on the physical mechanism of the ionospheric dynamo,which is responsible for daily variations of the geomagnetic field.The performance in Sq geomagnetic field modeling was investigated using the Macao Science Satellite-1(MSS-1)data.Our model can enhance the physics-based framework of comprehensive geomagnetic field modeling for the MSS-1 and ensuing missions.
文摘High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science Satellite-1A (MSS-1A),added to data from other space-based magnetometers,should increase significantly the ability of scientists to observe changes in Earth’s magnetic field over time and space.Additionally,the MSS-1A’s FGM is intended to help identify magnetic disturbances affecting the spacecraft itself.This report focuses on the in-flight calibration of the MSS-1 FGM.A scalar calibration,independent of geomagnetic field models,was performed to correct offsets,sensitivities,and misalignment angles of the FGM.Using seven months of data,we find that the in-flight calibration parameters show good stability.We determined Euler angles describing the rotational relationship between the FGM and the Advanced Stellar Compass (ASC) coordinate system using two approaches:calibration with the CHAOS-7 geomagnetic field model,and simultaneous estimation of Euler angles and Gaussian spherical harmonic coefficients through self-consistent modeling.The accuracy of Euler angles describing the rotation was better than 18 arcsec.The calibrated FGM data exhibit good agreement with the calibrated data of the Vector Field Magnetometer (VFM),which is the primary vector magnetometer of the satellite.These calibration efforts have significantly improved the accuracy of the FGM measurements,which are now providing reliable data for geomagnetic field studies that promise to advance our understanding of the Earth’s magnetic environment.
基金funded by NSFC under grants 12250014, 42250101 and 12403068supported by youth funding of Jiangsu province BK20241707+1 种基金supported by the Macao FoundationXinjiang Uygur Autonomous Region for the support through “Tianchi Talent” special expert project。
文摘Strong flares and/or coronal mass ejections(CMEs) could bring us disastrous space weather,destroy crucial technology in space,and cause a large-scale blackout during some extreme cases.They frequently cause geomagnetic storms,which is a sudden disturbance of the Earth's magnetosphere.It is well accepted that CMEs play a dominant role in causing geomagnetic storms by a direct impact,but it is still not very clear regarding their association with solar flares.The association would be helpful for forecasting geomagnetic storms directly from flares,which are much easier to observe.The Macao Science Satellite-1(MSS-1) mission,with the scientific aim of studying the origin and evolution of the geomagnetic field,is able to accurately measure the vector geomagnetic field.Besides,it measures rapid spectral evolution of the solar X-ray irradiance of solar flares.In this study,we analyzed measurements by MSS-1 during a series of X-class flares in October of 2024,and saw the relationship between the flares and the associated geomagnetic storms.The observations support that the major geomagnetic storms tend to be associated with flares' duration in addition to flare class.We also find that long duration ones have radiated more energy in the extreme ultraviolet waveband.Being equally important,our results show that the magnetic fields measured by MSS-1,especially its external(e_(1)^(0)) coefficient,can well be used for monitoring the geomagnetic disturbance.
基金support from the National Natural Science Foundation of China(No.42274027)the Fundamental Research Funds for the Central Universitiessupported also by the Macao Foundation。
文摘This study utilizes radio occultation observations from the Macao Science Satellite-1 mission(MSS-1)to investigate ionospheric response to the May 2024 G5 geomagnetic storm within the South Atlantic Anomaly(SAA)region.The distinctive data from MSS-1,complemented by observations from the ground-based Global Navigation Satellite System(GNSS)and the Constellation Observing System for Meteorology,Ionosphere,and Climate follow-on satellite mission(COSMIC-2),reveal a super plasma fountain effect during the main phase of the storm.This effect was marked by peaks in the equatorial ionization anomaly that extended beyond their typical latitude range.The MSS-1 observations,particularly in the northern hemisphere of the SAA region,confirm the role of prompt penetration electric fields in driving ionospheric disturbances and amplifying scintillation at higher altitudes.The study also identifies a decrease in total electron content and a reduction in scintillation occurrence during the recovery phase of the storm.The results demonstrate the pivotal role that MSS-1 observations can play,when combined with ground-based and COSMIC-2 observations,in providing a more comprehensive understanding of ionospheric response to severe geomagnetic storms.
基金supported by the National Natural Science Foundation of China (42388101)the CAS Youth Interdisciplinary Team (JCTD-2021-05)funded by the Youth Innovation Promotion Association, Chinese Academy of Sciences.
文摘Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and Earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on Earth,while also deepening our knowledge of stellar physics and solar system dynamics.Determining the solar cycles between 1600 and 1700-especially the post-1645 Maunder Minimum,characterized by significantly reduced solar activity-poses challenges to existing solar activity proxies.This study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to 1700.Remarkably,a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles,diverging from the widely accepted record of 12 cycles during that time.This research enhances our understanding of historical solar activity,and underscores the importance of integrating diverse historical sources into modern analyses.
基金supported by the National Key R&D Program of China (Grant No.2022YFF0503700)the special funds of Hubei Luojia Laboratory (Grant No.220100011)+1 种基金supported by the International Space Science Institute–Beijing(ISSI-BJ) project“The Electromagnetic Data Validation and Scientific Application Research based on CSES Satellite”and ISSI/ISSI-BJ project,“Multi-Scale Magnetosphere–Ionosphere–Thermosphere Interaction.”
文摘The Michelson Interferometer for Global High-resolution Thermospheric Imaging(MIGHTI)onboard the Ionospheric Connection Explorer(ICON)satellite offers the opportunity to investigate the altitude profile of thermospheric winds.In this study,we used the red-line measurements of MIGHTI to compare with the results estimated by Horizontal Wind Model 14(HWM14).The data selected included both the geomagnetic quiet period(December 2019 to August 2022)and the geomagnetic storm on August 26-28,2021.During the geomagnetic quiet period,the estimations of neutral winds from HWM14 showed relatively good agreement with the observations from ICON.According to the ICON observations,near the equator,zonal winds reverse from westward to eastward at around 06:00 local time(LT)at higher altitudes,and the stronger westward winds appear at later LTs at lower altitudes.At around 16:00 LT,eastward winds at 300 km reverse to westward,and vertical gradients of zonal winds similar to those at sunrise hours can be observed.In the middle latitudes,zonal winds reverse about 2-4 h earlier.Meridional winds vary more significantly than zonal winds with seasonal and latitudinal variations.According to the ICON observations,in the northern low latitudes,vertical reversals of meridional winds are found at 08:00-13:00 LT from 300 to 160 km and at around 18:00 LT from 300 to 200 km during the June solstice.Similar reversals of meridional winds are found at 04:00-07:00 LT from 300 to 160 km and at 22:00-02:00 LT from 270 to 200 km during the December solstice.In the southern low latitudes,meridional wind reversals occur at 08:00-11:00 LT from 200 to 160 km and at 21:00-02:00 LT from 300 to 200 km during the June solstice.During the December solstice,reversals of the meridional wind appear at 20:00-01:00 LT below 200 km and at 06:00-11:00 LT from 300 to 160 km.In the northern middle latitudes,the northward winds are dominant at 08:00-14:00 LT at 230 km during the June solstice.Northward winds persist until 16:00 LT at 160 and 300 km.During the December solstice,the northward winds are dominant from 06:00 to 21:00 LT.The vertical variations in neutral winds during the geomagnetic storm on August 26-28 were analyzed in detail.Both meridional and zonal winds during the active geomagnetic period observed by ICON show distinguishable vertical shear structures at different stages of the storm.On the dayside,during the main phase,the peak velocities of westward winds extend from a higher altitude to a lower altitude,whereas during the recovery phase,the peak velocities of the westward winds extend from lower altitudes to higher altitudes.The velocities of the southward winds are stronger at lower altitudes during the storm.These vertical structures of horizontal winds during the storm could not be reproduced by the HWM14 wind estimations,and the overall response to the storm of the horizontal winds in the low and middle latitudes is underestimated by HWM14.The ICON observations provide a good dataset for improving the HWM wind estimations in the middle and upper atmosphere,especially the vertical variations.
基金supported by the Special Fund of the Institute of Geophysics,China Earthquake Administration(grant no.DQJB24X25).
文摘The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constellation data from the Chinese Seismo-Electromagnet Satellite(CSES)and Swarm satellites to extract the SV in China and surrounding areas,based on the Geomagnetic Virtual Observatory(GVO)method.On this basis,we have developed two GVO products:the core field,and the SV series.The accuracies of these products are assessed using ground observatories measurements and geomagnetic field model.Moreover,the results indicate that the GVO products align well with the series from ground observatories and the CHAOS model.The majority of root-mean-square deviation(RMSE)values of the core field series are less than 5 nT,consistent with the INTERMAGNET standards for quasi-definitive data.In the GVO core field series,the maximum accuracy of one-month and four-month intervals are 2.24 nT and 1.16 nT,respectively.In the GVO SV series,the maximum accuracy of one-month and four-month intervals are 2.03 nT/yr and 1.36 nT/yr,respectively.The GVO SV series effectively capture geomagnetic jerks without losing temporal resolution comparing with the recording of ground observatories.We demonstrate that the GVO method serves as an effective and precise tool for extracting SV information of geomagnetic fields.In the GVO products,the RMSE of the horizontal component exceeds that of the vertical component,and the magnitude of RMSE deviation correlates with solar activity levels.With more and more geomagnetic satellites in orbit,we wish to use multi-constellation magnetic satellite data to assess the geomagnetic field more accurately.
基金supported by the National Natural Science Foundation of China(42250101,42250102,42250103,12250013)the Macao Foundation。
文摘The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized lithosphere,and the space current systems.Modeling of the lithospheric contribution plays an important role in the geophysical studies and industrial applications.In this paper,we propose a new method for global and regional modeling of the lithospheric magnetic field based on the cubed-sphere.An equivalent dipole source method on a quasi-uniform cubed-sphere grid is employed in the forward modeling.The dipole directions are fixed according to a priori magnetization and the relative intensities are estimated by an inversion procedure of least-squares fitting with minimum model regularization.Several numerical tests are performed to validate the accuracy and efficiency of both forward modeling and inversion procedure.The proposed method is applied to the global and regional modeling based on the latest magnetic data from Swarm Alpha satellite and MSS-1 mission.The model results indicate that the proposed method works quite well for realistic satellite data and MSS-1 data is consistent with the Swarm data in terms of lithospheric field modeling.
文摘The Kashmir Basin,shaped by the collision of the Indian and Eurasian tectonic plates,features prominent faults,including the Balapur fault and other fault zones.This study focuses on the Gulmarg fault within the Northwestern Himalaya,using advanced geomagnetic techniques for delineation.Geomagnetic measurements reveal the characteristics of the newly identified Gulmarg fault.Ground magnetic surveys with Proton Precession Magnetometers along linear profiles and a magnetic grid highlight fault-related anomalies.The results indicate a fault running through the Gulmarg meadows,approximately 1.6 km from the Balapur fault,suggesting a potential coupling between the two.Three profiles across the fault exhibit distinctive magnetic variations,highlighting the intricate nature of the fault structure.Gridding methods also reveal anomalies associated with subsurface water and hydraulic activities,underscoring the importance of advanced geophysical techniques.This study emphasizes the significance of detailed investigations to unravel the complex geological processes shaping the Kashmir Basin.The study provides valuable insights into the tectonic activity in the Gulmarg region,underscoring the role of geophysical studies in enhancing our understanding of dynamic geological structures like the Gulmarg fault zone.
基金supported by the National Research and Innovation Agency(BRIN),Indonesia.
文摘Ionospheric scintillation refers to rapid radio signal amplitude and phase fluctuations due to small-scale irregularities in the ionosphere.Occurring primarily at equatorial and low latitudes,scintillation is linked to equatorial plasma bubbles(EPBs),regions of depleted plasma density that form after sunset.Ionospheric scintillation typically occurs from post-sunset hours until midnight.Post-sunset EPBs can be enhanced or suppressed during geomagnetic storms,depending on local sunset timing and how it relates to the storm's main or recovery phases.This study analyzes ionospheric scintillation in Indonesia,located at low geomagnetic and geographic latitudes,during geomagnetic events from 2003 to 2024.Using the S4 index,scintillation was examined with data from seven observation stations during geomagnetic storm events.Geomagnetic activity was evaluated using Dst,SYM-H,and AE indices,employing Superposed Epoch Analysis(SEA)to assess scintillation occurrence linked to minimum SYM-H,defined as epoch 0 to represent the storm peak or the onset of recovery phase in each event.The analysis categorized geomagnetic storms into weak-moderate(–100 nT<min.Dst≤–30 nT)and strong(min.Dst≤–100 nT),and examined their dependence on the local time of minimum SYM-H.Results indicate that scintillation first appears~6 hours after epoch 0 in weak-moderate geomagnetic storms,and~12 hours after epoch 0 in strong geomagnetic storms.The average AE index returns to its baseline value(quiet condition)~6 and~12 hours after epoch 0 for weak-moderate and strong geomagnetic storms,respectively.Further analysis based on the classification of the local time of epoch 0 shows that scintillation occurrence is not observed in post-sunset hours when epoch 0 falls between 16:00 and 19:00 LT for weak-moderate geomagnetic storms.In strong geomagnetic storms,scintillation occurrence during post-sunset hours is absent when epoch 0 is between 10:00 and 19:00 LT.Notably,when the minimum SYM-H(epoch 0)nearly coincides with local sunset,scintillation activity occurs around sunset in both weak-moderate and strong geomagnetic storms.Furthermore,when epoch 0 falls within midnight until early morning,scintillation can be generated in the post-sunset hours before epoch 0.Still,post-midnight scintillation is not observed in the equatorial region during the recovery phase of either weak-moderate and strong storm events.Our findings show that when sunset falls before or coincide with epoch 0,the likelihood of post-sunset EPB and scintillation increases,due to the prompt-penetration electric field(PPEF)in the main phase of storm.The disturbance dynamo electric field(DDEF)in the recovery phase driven by equatorward winds from auroral Joule heating operates for at least 6-and 12-hours post-epoch 0 in the cases of weak-moderate and strong geomagnetic storms,respectively.When the local sunset falls within these operational DDEF periods,post-sunset EPBs will likely be suppressed,inhibiting ionospheric scintillation during post-sunset hours.Finally,this study provides essential information for developing more accurate ionospheric scintillation prediction models in space weather services in equatorial regions.
