We normalize data from 43 Chinese observatories and select data from ten Chinese observatories with most continuous records to assess the secular variations(SVs)and geomagnetic jerks by calculating the deviations betw...We normalize data from 43 Chinese observatories and select data from ten Chinese observatories with most continuous records to assess the secular variations(SVs)and geomagnetic jerks by calculating the deviations between annual observed and CHAOS-6 model monthly means.The variations in the north,east,and vertical eigendirections are studied by using the covariance matrix of the residuals,and we find that the vertical direction is strongly affected by magnetospheric ring currents.To obtain noise-free data,we rely on the covariance matrix of the residuals to remove the noise contributions from the largest eigenvalue or vectors owing to ring currents.Finally,we compare the data from the ten Chinese observatories to seven European observatories.Clearly,the covariance matrix method can simulate the SVs of Dst,the jerk of the northward component in 2014 and that of the eastward component in 2003.5 in China are highly agree with that of Vertically downward component in Europe,compare to CHAOS-6,covariance matrix method can show more details of SVs.展开更多
Spatiotemporal variations of the nondipole （ND） magnetic field over the Chinese mainland and neighboring regions from 10000 BC to 1990 AD were analyzed using the latest global geomagnetic models CALS10K.1b, CALS3K.4...Spatiotemporal variations of the nondipole （ND） magnetic field over the Chinese mainland and neighboring regions from 10000 BC to 1990 AD were analyzed using the latest global geomagnetic models CALS10K.1b, CALS3K.4, and IGRF 11. Moreover, for field sources, we investigated 2 n （n = 2 -10） pole ND fields and their energies. The results suggest that the study period can be divided into three. The intensity of the ND field has been mainly positive since 10000 BC and lasted almost 7500 years, then gradually decreased to negative in 2500 BC to 1500 AD, and finally sharply increased to positive. The anomaly areas of the ND field in East Asia took shape for n - 3, when the anomaly areas in East Asia were shaped into closed circles in the mainland. This suggests that the first three harmonic degrees account for most of the ND field. The energy of the ND field rapidly attenuates at the core mantle boundary and is stable at the surface.展开更多
This study utilizes the 62208000 Swarm satellite data to establish a high-precision main magnetic field at the height of the satellites in China and its adjacent regions.The CHAOS-6 model is used to remove the crustal...This study utilizes the 62208000 Swarm satellite data to establish a high-precision main magnetic field at the height of the satellites in China and its adjacent regions.The CHAOS-6 model is used to remove the crustal and external fields and obtain 2788 main field grid data.We use the main field grid data to build a three-dimensional(3D)surface spline(3DSS)model of the satellite altitude in China.Other regional models(namely the 3D,two-dimensional(2D)Taylor,and 2D surface spline models)and the CHAOS-6 model are employed to model and analyze the same region.The results show that the 3DSS model can represent a good fi tting for the northward(X)and eastward(Y)components and the total intensity(F).This model demonstrates the most stable results for the 20 points that did not take part in the modeling.Compared with the other three regional models,the root–mean–square error values and the average residuals of the new model are approximately 65%and 69%lower for each component,respectively.This study does not rely on ground station data to derive a more accurate regional main fi eld model.The results further show that less data height difference and high-density data distributions greatly improve the regional model accuracy.The new model has a certain application value to related space geophysics,such as in spatial positioning and navigation,and to the study of regional magnetic anomalies.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41404053)Special Project for Meteo-Scientifi c Research in the Public Interest(No.GYHY201306073)
文摘We normalize data from 43 Chinese observatories and select data from ten Chinese observatories with most continuous records to assess the secular variations(SVs)and geomagnetic jerks by calculating the deviations between annual observed and CHAOS-6 model monthly means.The variations in the north,east,and vertical eigendirections are studied by using the covariance matrix of the residuals,and we find that the vertical direction is strongly affected by magnetospheric ring currents.To obtain noise-free data,we rely on the covariance matrix of the residuals to remove the noise contributions from the largest eigenvalue or vectors owing to ring currents.Finally,we compare the data from the ten Chinese observatories to seven European observatories.Clearly,the covariance matrix method can simulate the SVs of Dst,the jerk of the northward component in 2014 and that of the eastward component in 2003.5 in China are highly agree with that of Vertically downward component in Europe,compare to CHAOS-6,covariance matrix method can show more details of SVs.
基金supported by the National Natural Science Foundation of China(Grant No.41404053)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140994)
文摘Spatiotemporal variations of the nondipole （ND） magnetic field over the Chinese mainland and neighboring regions from 10000 BC to 1990 AD were analyzed using the latest global geomagnetic models CALS10K.1b, CALS3K.4, and IGRF 11. Moreover, for field sources, we investigated 2 n （n = 2 -10） pole ND fields and their energies. The results suggest that the study period can be divided into three. The intensity of the ND field has been mainly positive since 10000 BC and lasted almost 7500 years, then gradually decreased to negative in 2500 BC to 1500 AD, and finally sharply increased to positive. The anomaly areas of the ND field in East Asia took shape for n - 3, when the anomaly areas in East Asia were shaped into closed circles in the mainland. This suggests that the first three harmonic degrees account for most of the ND field. The energy of the ND field rapidly attenuates at the core mantle boundary and is stable at the surface.
基金supported by the National Natural Science Foundation of China (Nos. 42030203, 41974073, and 41404053)
文摘This study utilizes the 62208000 Swarm satellite data to establish a high-precision main magnetic field at the height of the satellites in China and its adjacent regions.The CHAOS-6 model is used to remove the crustal and external fields and obtain 2788 main field grid data.We use the main field grid data to build a three-dimensional(3D)surface spline(3DSS)model of the satellite altitude in China.Other regional models(namely the 3D,two-dimensional(2D)Taylor,and 2D surface spline models)and the CHAOS-6 model are employed to model and analyze the same region.The results show that the 3DSS model can represent a good fi tting for the northward(X)and eastward(Y)components and the total intensity(F).This model demonstrates the most stable results for the 20 points that did not take part in the modeling.Compared with the other three regional models,the root–mean–square error values and the average residuals of the new model are approximately 65%and 69%lower for each component,respectively.This study does not rely on ground station data to derive a more accurate regional main fi eld model.The results further show that less data height difference and high-density data distributions greatly improve the regional model accuracy.The new model has a certain application value to related space geophysics,such as in spatial positioning and navigation,and to the study of regional magnetic anomalies.
