The period and quality factor of the Chandler wobble(CW)are useful for constraining the Earth’s internal structure properties,such as the mantle elasticity.It has been shown that the CW is mainly excited by a combina...The period and quality factor of the Chandler wobble(CW)are useful for constraining the Earth’s internal structure properties,such as the mantle elasticity.It has been shown that the CW is mainly excited by a combination of atmospheric and oceanic processes;hence based on a deconvolution method,we can remove them from the excitation sequence of the CW to estimate its period P and quality factor Q.We finally re-estimate P=432.3±0.8 days and Q=85±15 for the CW.Based on those two estimates,we investigate the relationship between the geomagnetic jerks and the excitation sequences of the CW.The geomagnetic jerks or jerk bounds are well consistent with the sudden changes of the excitation sequences of the CW.This demonstrates that the geomagnetic jerks could be a possible excitation source of the CW.It is crucial for understanding the excitation of the CW and for deeper geophysical insights into the geomagnetic jerks.展开更多
The high level of noise is a special feature of the geomagnetic field on the territory of Slovenia. The tension of the Adriatic tectonic microplate, on which Slovenia entirely lies, was recognized as one of its source...The high level of noise is a special feature of the geomagnetic field on the territory of Slovenia. The tension of the Adriatic tectonic microplate, on which Slovenia entirely lies, was recognized as one of its sources. The interior of the Earth is also the source of geomagnetic jerks. They are impulses in the secular variation calculated on the basis of monthly or annual mean values of variation of the geomagnetic field. The paper presents an analysis of accelerations in a local magnetic field calculated on the bases of daily mean values of the magnetic field measured at PIA geomagnetic Observatory (Piran, Slovenia) in 2020. These accelerations indicate geomagnetic impulses at the regional level over days or weeks. Then these results are compared with the registered seismic activity in the West Balkans.展开更多
The temporal and spatial evolution characteristics of the geomagnetic secular acceleration(SA) are investigated, based on CHAOS-4 core field model during the period of 1997–2013. The SA evolution on a short time scal...The temporal and spatial evolution characteristics of the geomagnetic secular acceleration(SA) are investigated, based on CHAOS-4 core field model during the period of 1997–2013. The SA evolution on a short time scale is associated with the phenomenon of the geomagnetic jerk. More details of the global extent and the occurrence time of the successive jerks(the 1999, 2003, 2007, and 2011 jerks) are obtained. The location, size and reversed polarity pattern for the 1999 jerk are similar to those for the 2003 jerk in the Asian-Indian sector. While the 2007 and 2011 jerks mainly take place in the Atlantic sector. The direction and speed of the shift for the four jerks are different, identified by the occurrence time of the jerks. The zonal motions of the SA patches exhibit an oscillation pattern in the Asian-Indian sector, whereas a purely westward drifting pattern is along the equator in the Atlantic sector. It is believed that the shift of the jerks is related to the motion of SA-B_r patches observed at the core-mantle boundary(CMB).展开更多
基金supported by the NSFC(grants No.41774024,41721003,41974022)by Educational Commission of Hubei Province of China(grant No.2020CFA109)the Project Supported by the Special Fund of Hubei Luojia Laboratory
文摘The period and quality factor of the Chandler wobble(CW)are useful for constraining the Earth’s internal structure properties,such as the mantle elasticity.It has been shown that the CW is mainly excited by a combination of atmospheric and oceanic processes;hence based on a deconvolution method,we can remove them from the excitation sequence of the CW to estimate its period P and quality factor Q.We finally re-estimate P=432.3±0.8 days and Q=85±15 for the CW.Based on those two estimates,we investigate the relationship between the geomagnetic jerks and the excitation sequences of the CW.The geomagnetic jerks or jerk bounds are well consistent with the sudden changes of the excitation sequences of the CW.This demonstrates that the geomagnetic jerks could be a possible excitation source of the CW.It is crucial for understanding the excitation of the CW and for deeper geophysical insights into the geomagnetic jerks.
文摘The high level of noise is a special feature of the geomagnetic field on the territory of Slovenia. The tension of the Adriatic tectonic microplate, on which Slovenia entirely lies, was recognized as one of its sources. The interior of the Earth is also the source of geomagnetic jerks. They are impulses in the secular variation calculated on the basis of monthly or annual mean values of variation of the geomagnetic field. The paper presents an analysis of accelerations in a local magnetic field calculated on the bases of daily mean values of the magnetic field measured at PIA geomagnetic Observatory (Piran, Slovenia) in 2020. These accelerations indicate geomagnetic impulses at the regional level over days or weeks. Then these results are compared with the registered seismic activity in the West Balkans.
基金supported by the National Basic Research Program of China (Grant Nos. 2014CB845903, 2012CB825604)the National Natural Science Foundation of China (Grant Nos. 41174122, 41031066, 41104093, 41574162, & 41204122)
文摘The temporal and spatial evolution characteristics of the geomagnetic secular acceleration(SA) are investigated, based on CHAOS-4 core field model during the period of 1997–2013. The SA evolution on a short time scale is associated with the phenomenon of the geomagnetic jerk. More details of the global extent and the occurrence time of the successive jerks(the 1999, 2003, 2007, and 2011 jerks) are obtained. The location, size and reversed polarity pattern for the 1999 jerk are similar to those for the 2003 jerk in the Asian-Indian sector. While the 2007 and 2011 jerks mainly take place in the Atlantic sector. The direction and speed of the shift for the four jerks are different, identified by the occurrence time of the jerks. The zonal motions of the SA patches exhibit an oscillation pattern in the Asian-Indian sector, whereas a purely westward drifting pattern is along the equator in the Atlantic sector. It is believed that the shift of the jerks is related to the motion of SA-B_r patches observed at the core-mantle boundary(CMB).
