蒙城台地电场资料分析

通过对安徽省蒙城台2002年地电场分钟值数据的处理分析, 结果认为该台可以清晰地记录到大地电场的正常日变化、电磁暴; 同一方向长短极距的变化基本同步; NS向、EW向与NW向的比测误差基本正常; 拟合极化方向角在静日和有电磁暴时, 在N80°W^N100°W内摆动, 较稳定, 有干扰和雷电时极化方向明显偏转; 大地电场矢量方向角α变化大。受降雨、外线接触不良、仪器工作状况不佳的影响, 少数数据质量不好, 通过改进, 还可以进一步提高观测质量。

Effect of Sand and Dust Storms on Microwave Propagation Signals in Southern Libya

The propagation of electromagnetic waves in millimeter band is severely affected by rain, and dust particles in terms of attenuation and de-polarization. The computations of dust and/or sand storms require knowledge of electrical properties of the scattering particles and climate conditions at the studied region. To compute the effect of dust and sand particles on the propagation of electromagnetic waves, it is required to collect the sand particles carried out by the wind, measure the particles size, calculate the concentration, and carry chemical analysis of the contents, then the dielectric constant can be calculated. The main object of this paper is to study the effect of sand and dust storms on wireless communication, such as microwave links, in the southern region of Libya （Sebha, Ashati, Obari, Morzok, Ghat） by determining the attenuation. The result showed that there is some consideration that has to be taken into account in the communication power budget.

日震 月震 星震

地震,不仅仅是发生在地球上,在太阳、月亮和别的星球上也会有类似于地震的现象发生,它们分别被称为"日震"、"月震"、"星震"。太阳发生剧烈的震动,被称为"日震"。1962年,科学家发现了太阳的表面上下震动着,一次的周期约为5分钟。后来,又观测到其震动是周期在20～160分钟内不等的各种连续震动。

The causal sequence investigation of the ring current ion-flux increasing and the magnetotail ion injection during a major storm

Comprehensive records are available in ENA data of ring current activity recorded by the NUADU instrument aboard TC-2 on 15 May, 2005 during a major magnetic storm （which incorporated a series of substorms）. Ion fluxes at 4-min temporal resolution derived from ENA data in the energy ranges 50-81 and 81-158 keV are compared with in situ particle fluxes measured by the LANL-SOPA instruments aboard LANL-01, LANL-02, LANL-97, and LANL-84 （a series of geostationary satellites that encircle the equatorial plane at -6.6 RE）. Also, magnetic fields measured simultaneously by the magetometers aboard GOES-10 and GOES-12 （which are also geostationary satellites） are compared with the particle data. It is demonstrated that ion fluxes in the ring current were enhanced during geomagnetic field tailward stretching in the growth phases of substorms rather than after Earthward directed dipolarization events. This observation, which challenges the existing concept that ring current particles are injected Earthward from the magnetotail following dipolarization events, requires further investigation using a large number of magnetic storm events.

Comparison between the ring current energy injection and decay under southward and northward IMF Bz conditions during geomagnetic storms

The geomagnetic storm is one of the most important geomagnetic disturbance phenomena in the geospace.Many studies assume that input of solar wind energy into the Earth's ring current only occurs when IMF Bz in GSM coordinates is southward;the ring current energy injection and decay under northward IMF Bz are not well understood and still need further investigation.In this paper,by using the large amount of data from the year 1964 to 2010,we use the empirical phase space analysis method to study the ring current energy injection and decay under northward IMF Bz and compare the results with those under southward IMF Bz condition.We have found that the largest injection Q under northward IMF Bz condition is only 7% of the largest injection under southward IMF Bz,implying that there is a very limit energy injected into the ring current region when IMF Bz is northward.The decay time decreases as VBz increases and shows a good linear trend for southward IMF Bz;while for the northward IMF Bz,there is not a clear relation between τ varies and VBz.Having taken τ as a function of injection Q instead of VBz,we have obtained the empirical relation of τ with Q for northward and southward IMF Bz conditions:the two categories are further combined together and the empirical relation τ= e(2.6 0.039 Q) is derived.Further,the pressure-corrected Dst formula Dst=Dst b P+c is derived for both southward and northward IMF Bz conditions,where the coefficients b and c are 6.9/10.4 and 10.0/15.2 when IMF Bz is southward and northward respectively.The statistical results on between the different geomagnetic indices(Dst,Kp,AE) and IMF Bz are also obtained.

Case study of ionospheric fluctuation over mid-latitude region during one large magnetic storm

From Nov. 6 to 10, 2004, a large number of solar events occurred, which triggered many solar flares and coronal mass ejections (CMEs). These CMEs caused two large geomagnetic storms and continuous energy proton events. During this period, one large positive ionospheric storm happened over the East-Asian region on Nov. 8, 2004. On Nov. 10, 2004, a strong spread-F was observed by the ionosonde located in the mid-latitude region of East China and Japan, and the ionospheric fluctuation over the ionosonde stations derived from GPS observation was also obvious. In this report, the characteristics of the spatial distribution of the ionosphere fluctuation and its temporal evolution are studied using the parameter of the rate of total electron content (ROT) derived from dual-frequency GPS measurement. Strong fluctuating activity of the ionosphere was found over the mid-latitude region in the southern and northern hemispheres between longitudes of 100°E and 180°E during the magnetic storm period on Nov. 10, 2004, and a regular movement of the disturbing region was observed. In the end, the reason of the ionospheric fluctuation during this magnetic storm is analyzed.

Radial propagation of magnetospheric substorm-injected energetic electrons observed using a BD-IES instrument and Van Allen Probes

In cases where substorm injections can be observed simultaneously by multiple spacecraft,they can help elucidate the potential mechanisms of particle transport and energization,of great importance to understanding and modeling the magnetosphere.In this paper,using data returned from the BeiDa-IES（BD-IES） instrument onboard a satellite in an inclined（55°） geosynchronous orbit（IGSO）,in combination with two geo-transfer orbiting（GTO） satellite Van Allen Probes（A and B）,we analyze a substorm injection event that occurred on the 16 th of October 2015.During this substorm injection,the IGSO onboard BD-IES was outbound,while both Van Allen Probe satellites（A and B） were inbound,a configuration of multiple trajectories that provides a unique opportunity to simultaneously investigate both the inward and outward radial propagation of substorm injection.Indicated by AE/AL indices,this substorm was closely related to an IMF/solar wind discontinuity that showed a sharp change in IMF Bz direction to the north.The innermost signature of this substorm injection was detected by Van Allen Probes A and B at L-3.7,while the outermost signature was observed by the onboard BD-IES instrument at L-10.These data indicate that the substorm had a global,rather than just local,effect.Finally,we suggest that electric fields carried by fast-mode compressional waves around the substorm injection are the most likely candidate mechanism for the electron injection signatures observed in the inner- and outermost inner magnetosphere.

Dynamic variations of the outer radiation belt during magnetic storms for 1.5–6.0 MeV electrons

The CME’s structure of solar wind(interplanetary magnetic field)is different from CIR’s.The two processes in which plasma and solar wind energy are injected into the Earth’s inner magnetosphere are not the same.So,the variations of energetic elec- trons flux in the radiation belts are different between the storms associated with CMEs and CIRs.By using data from SAMPEX(Solar,Anomalous,and Magnetospheric Particle Explorer)satellite,we have investigated the dynamic variations of the outer radiation belt for 1.5–6.0 MeV electrons during 54 CME-driven storms and 26 CIR-driven recurrent storms.According to the superposed epoch analysis,for CME-and CIR-driven storms,when the Dst index reaches the minimum,the locations of the outer boundary move to L=4 and L=5.5,respectively.In the recovery phases,the locations of the outer boundary of the outer radiation belt are generally lower than and slightly higher than those before CME-and CIR-driven storms,respectively.We have found that the logarithmically decaying 1/e cut-off L-shell is a satisfying indicator of the outer boundary of the outer radiation belt.Furthermore,our study shows that the logarithmically decaying 1/e cut-off latitude is dependent on the Kp index in the main phases of CME-and CIR-driven storms,while in the recovery phases,there is no obvious correlation.In ad- dition,it has been shown that the locations of the peak electron flux are controlled by the minimum Dst index in the main phases of CME-driven storms.The influences of multiple storms on the electron flux of outer radiation belt have also been in- vestigated.

Numerical study on the response of the Earth's magnetosphere-ionosphere system to a super solar storm

With the approaching of the 24th solar cycle peak year （2012-2014）, the impacts of super solar storms on the geospace envi- ronment have drawn attentions. Based on the geomagnetic field observations during Carrington event in 1859, we estimate the interplanetary solar wind conditions at that time, and investigate the response of the magnetosphere-ionosphere system to this extreme solar wind conditions using global 3D MHD simulations. The main findings include： l） The day-side magnetopause and bow shock are compressed to 4.3 and 6.0 Re （Earth radius）, and their flanks are also strongly compressed. The magneto- pause shifts inside the geosynchronous orbit, exposing geosynchronous satellites in the solar wind in the magnetosheath. 2） During the storm, the region-1 current increases by about 60 times, and the cross polar potential drop increases by about 80 times; the reconnection voltage is about 5 to 6 times larger than the average storms, which means a larger amount of the solar wind energy enters the magnetosphere, resulting in strong space weather phenomena.