The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free...The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free Core Nutation (FCN),from the Earth's liquid core resonance of gravity tide waves on the diurnal frequency band. Since 1987, some scientists in many different countries have come to calculate the parameters of FCN by using the observational data of gravity tide waves on the diumal frequency band. They basically followed the Stacking method, which needed five diurnal waves for the resolution. In this paper, authors introduced the Aky-Btk value method with clearly geometrical meaning as a new method, which only requires three very high signal-noise-ratio waves o1, K1 and P1 for the resolution. Authors chose the observational data of the three superconducting gravimeter stations respectively located in Cantley of Canada, Wuhan of China and Brussels of Belgium, to compute the parameters of FCN. It was the first time that the observational results of the parameters of FCN obtained from gravitational tide were in accord with the parameters of FCN gained from VLBI since 1987.展开更多
In the measurement of the Newtonian gravitational constant G with the time-of-swing method,the influence of the Earth's rotation has been roughly estimated before,which is far beyond the current experimental preci...In the measurement of the Newtonian gravitational constant G with the time-of-swing method,the influence of the Earth's rotation has been roughly estimated before,which is far beyond the current experimental precision.Here,we present a more complete theoretical modeling and assessment process.To figure out this effect,we use the relativistic Lagrangian expression to derive the motion equations of the torsion pendulum.With the correlation method and typical parameters,we estimate that the influence of the Earth's rotation on G measurement is far less than 1 ppm,which may need to be considered in the future high-accuracy experiments of determining the gravitational constant G.展开更多
The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes,particularly during geomagnetic storms.A dawn-dusk pattern has been detected ...The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes,particularly during geomagnetic storms.A dawn-dusk pattern has been detected during the storm main phase through near-Earth and in-situ magnetic measurements.This asymmetry is believed to arise from asymmetric solar windmagnetosphere coupling and is linked to the closure of the ring current.Recent evidence has confirmed the existence of asymmetric ring currents during quiet times and the storm recovery phase.This phenomenon may be closely related to the evolution of ring currents,including plasma injection and decay processes.In this study,the local time asymmetry of the ring current is estimated using data from low-Earth-orbit Swarm and Macao Science Satellite-1(MSS-1)missions.Spherical harmonics models are developed to quantify the magnetic field of ring currents through external Gauss coefficients during both quiet periods and the storm recovery phase.Several features of dawn-dusk asymmetry are observed in various cases in different months.(1)The maximum difference in magnetic value across local time ranges from 3 to 10 nT,showing relative invariance compared with various Sym-H levels.(2)Stronger magnetic signals are detected at the premidnight sector during quiet times and at the afternoon sector during the storm recovery phase.(3)Magnetic perturbations remain at a lower level during the postmidnight and morning sectors.Although the pattern of local time asymmetry differs between quiet times and the recovery phase,dawn-dusk asymmetry remains the most pronounced feature,affecting the trapping and loss of charged particles in the inner magnetosphere.Combining Swarm and MSS-1 magnetic observations can enable convenient monitoring of the detailed azimuthal local time effects of the ring current at various disturbance levels in the future.展开更多
For earthquakes (M≥4.0) occurring along and around the East Anatolian fault zone and the Dead Sea fault zone within ten years immediately before the MW7.8 Gaziantep earthquake,Türkiye,of February 6,2023,we explo...For earthquakes (M≥4.0) occurring along and around the East Anatolian fault zone and the Dead Sea fault zone within ten years immediately before the MW7.8 Gaziantep earthquake,Türkiye,of February 6,2023,we explored the correlation between seismicity and the earth's rotation.We statistically evaluated the correlation using the Schuster's test.The results are quantitatively assessed by a p-value.We found a clear downward trend in the p-values from early 2020 to late 2022 in the studied region.We also obtained a spatial distribution of the p-values showing a low p-value area near the northeastern end of the aftershock zone.Although the stress induced by the rotation of the earth is very weak,it could control the earthquake occurrence when the focal medium is loaded to the critical state to release a large earthquake.The decrease in the b-value in the Gutenberg-Richter (G-R) relation is considered in the form of the tectonic stress increase in the crust.We investigated the b-value as a function of time in the study region.We found that the b-value had decreased for about eleven years before the p-value started to decrease,with a relative reduction of 57%.Therefore,the result of the lower p-values obtained in the present study infers that the earthquakes were dominated by the earth's rotation prior to the MW7.8 Türkiye earthquake due to a critical state of the focal region.展开更多
For earthquakes(ML≥2.0) that occurred from January 2006 to October 2018 around the Ms5.7 Xingwen earthquake occurred on 16 December 2018 in Xingwen,Sichuan province,China,we statistically investigated the correlation...For earthquakes(ML≥2.0) that occurred from January 2006 to October 2018 around the Ms5.7 Xingwen earthquake occurred on 16 December 2018 in Xingwen,Sichuan province,China,we statistically investigated the correlation between the phase of Earth's rotation and the occurrence of earthquakes via Schuster's test to determine the signals that triggered earthquakes before the Ms5.7 Xingwen event.The results were evaluated based on the P-value where a smaller P-value corresponded to a higher correlation between the occurrence of an earthquake and Earth's rotation.We investigated the spatial distribution of Pvalues in the region around the epicenter of the Ms5.7 Xingwen event,and obtained a result exhibiting a extremely low-P-value region.The松5.7 event occurred inside near the northern boundary of this region.Furthermore,we analyzed the temporal evolution of P-values for earthquakes that occurred within the extremely low-P-value region and found that some extremely low P-values(less that 0.1%),i.e.,significant correlation,were calculated for earthquakes that occurred before the胚5.7 Xingwen earthquake.Among sixty・one earthquakes with the lowest P-value,occurred from May 2014 to April 2018,a vast majority of them occurred during the acceleration of Earth's rotation.The lower P-value obtained in this study reveals that the Xingwen source body probably was extremely unstable prior to the occurrence of the Ms5.7 Xingwen earthquake.展开更多
Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures ...Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures after they are produced by reconnection. Motivated by this simulation, we revisited the scale size of DFs in the dawn-dusk direction by using Cluster observations during the years when the inter-distance among Cluster spacecraft was between 1000 and 2000 km. We selected the DFs that were detected by more than one spacecraft and estimated the radii of these DFs by a simple geometrical analysis, which is based on comparison of DF normals observed by different spacecraft. We found a few DFs that were only a few ion inertial lengths in the dawn-dusk direction. These results point out the importance of multi-scale coupling during the evolution of DFs.展开更多
An unidentified geophysical event is first reported in this paper. It was recorded with Lacoste & Romberg earth tide gravity meter (ET 21) at Chinese Antarctic Zhongshan Station.
文摘The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free Core Nutation (FCN),from the Earth's liquid core resonance of gravity tide waves on the diurnal frequency band. Since 1987, some scientists in many different countries have come to calculate the parameters of FCN by using the observational data of gravity tide waves on the diumal frequency band. They basically followed the Stacking method, which needed five diurnal waves for the resolution. In this paper, authors introduced the Aky-Btk value method with clearly geometrical meaning as a new method, which only requires three very high signal-noise-ratio waves o1, K1 and P1 for the resolution. Authors chose the observational data of the three superconducting gravimeter stations respectively located in Cantley of Canada, Wuhan of China and Brussels of Belgium, to compute the parameters of FCN. It was the first time that the observational results of the parameters of FCN obtained from gravitational tide were in accord with the parameters of FCN gained from VLBI since 1987.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11575160 and 11805074)the Postdoctoral Science Foundation of China(Grant Nos.2017M620308 and 2018T110750).
文摘In the measurement of the Newtonian gravitational constant G with the time-of-swing method,the influence of the Earth's rotation has been roughly estimated before,which is far beyond the current experimental precision.Here,we present a more complete theoretical modeling and assessment process.To figure out this effect,we use the relativistic Lagrangian expression to derive the motion equations of the torsion pendulum.With the correlation method and typical parameters,we estimate that the influence of the Earth's rotation on G measurement is far less than 1 ppm,which may need to be considered in the future high-accuracy experiments of determining the gravitational constant G.
基金supported by the National Natural Science Foundation of China(Grant Nos.12250014,and 12250012)the Macao Foundation。
文摘The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes,particularly during geomagnetic storms.A dawn-dusk pattern has been detected during the storm main phase through near-Earth and in-situ magnetic measurements.This asymmetry is believed to arise from asymmetric solar windmagnetosphere coupling and is linked to the closure of the ring current.Recent evidence has confirmed the existence of asymmetric ring currents during quiet times and the storm recovery phase.This phenomenon may be closely related to the evolution of ring currents,including plasma injection and decay processes.In this study,the local time asymmetry of the ring current is estimated using data from low-Earth-orbit Swarm and Macao Science Satellite-1(MSS-1)missions.Spherical harmonics models are developed to quantify the magnetic field of ring currents through external Gauss coefficients during both quiet periods and the storm recovery phase.Several features of dawn-dusk asymmetry are observed in various cases in different months.(1)The maximum difference in magnetic value across local time ranges from 3 to 10 nT,showing relative invariance compared with various Sym-H levels.(2)Stronger magnetic signals are detected at the premidnight sector during quiet times and at the afternoon sector during the storm recovery phase.(3)Magnetic perturbations remain at a lower level during the postmidnight and morning sectors.Although the pattern of local time asymmetry differs between quiet times and the recovery phase,dawn-dusk asymmetry remains the most pronounced feature,affecting the trapping and loss of charged particles in the inner magnetosphere.Combining Swarm and MSS-1 magnetic observations can enable convenient monitoring of the detailed azimuthal local time effects of the ring current at various disturbance levels in the future.
基金supported by the China National Key Research and Development Program(2022YFF0800601)the Special fund of the Institute of Geophysics,China Earthquake Administration (DQJB23Z09)。
文摘For earthquakes (M≥4.0) occurring along and around the East Anatolian fault zone and the Dead Sea fault zone within ten years immediately before the MW7.8 Gaziantep earthquake,Türkiye,of February 6,2023,we explored the correlation between seismicity and the earth's rotation.We statistically evaluated the correlation using the Schuster's test.The results are quantitatively assessed by a p-value.We found a clear downward trend in the p-values from early 2020 to late 2022 in the studied region.We also obtained a spatial distribution of the p-values showing a low p-value area near the northeastern end of the aftershock zone.Although the stress induced by the rotation of the earth is very weak,it could control the earthquake occurrence when the focal medium is loaded to the critical state to release a large earthquake.The decrease in the b-value in the Gutenberg-Richter (G-R) relation is considered in the form of the tectonic stress increase in the crust.We investigated the b-value as a function of time in the study region.We found that the b-value had decreased for about eleven years before the p-value started to decrease,with a relative reduction of 57%.Therefore,the result of the lower p-values obtained in the present study infers that the earthquakes were dominated by the earth's rotation prior to the MW7.8 Türkiye earthquake due to a critical state of the focal region.
基金supported by National Key R&D Program of China (No. 2018YFC1503405)
文摘For earthquakes(ML≥2.0) that occurred from January 2006 to October 2018 around the Ms5.7 Xingwen earthquake occurred on 16 December 2018 in Xingwen,Sichuan province,China,we statistically investigated the correlation between the phase of Earth's rotation and the occurrence of earthquakes via Schuster's test to determine the signals that triggered earthquakes before the Ms5.7 Xingwen event.The results were evaluated based on the P-value where a smaller P-value corresponded to a higher correlation between the occurrence of an earthquake and Earth's rotation.We investigated the spatial distribution of Pvalues in the region around the epicenter of the Ms5.7 Xingwen event,and obtained a result exhibiting a extremely low-P-value region.The松5.7 event occurred inside near the northern boundary of this region.Furthermore,we analyzed the temporal evolution of P-values for earthquakes that occurred within the extremely low-P-value region and found that some extremely low P-values(less that 0.1%),i.e.,significant correlation,were calculated for earthquakes that occurred before the胚5.7 Xingwen earthquake.Among sixty・one earthquakes with the lowest P-value,occurred from May 2014 to April 2018,a vast majority of them occurred during the acceleration of Earth's rotation.The lower P-value obtained in this study reveals that the Xingwen source body probably was extremely unstable prior to the occurrence of the Ms5.7 Xingwen earthquake.
基金supported by the National Natural Science Foundation of China (NSFC) under grant 41774154 and 41504123the Science Foundation of Jiangxi Province under grant 20122BAB21 2002+1 种基金the Nanchang University graduate innovation special fund project under grant CX2017106the Key Industry Innovation Chain of Shaanxi under grant 2018JQ4032
文摘Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures after they are produced by reconnection. Motivated by this simulation, we revisited the scale size of DFs in the dawn-dusk direction by using Cluster observations during the years when the inter-distance among Cluster spacecraft was between 1000 and 2000 km. We selected the DFs that were detected by more than one spacecraft and estimated the radii of these DFs by a simple geometrical analysis, which is based on comparison of DF normals observed by different spacecraft. We found a few DFs that were only a few ion inertial lengths in the dawn-dusk direction. These results point out the importance of multi-scale coupling during the evolution of DFs.
文摘An unidentified geophysical event is first reported in this paper. It was recorded with Lacoste & Romberg earth tide gravity meter (ET 21) at Chinese Antarctic Zhongshan Station.
