地磁场Z分量的年变化

利用河北省及邻区共8个台的绝对磁测Z分量的资料，分析了地磁场Z分量的年变化。结果是，曲线相对长斜线而言，一年中形成两个峰值，时间在4月份和10月份前后。每年1、7、12月份为低值，7月份最低。相对长斜线的年变最大幅度各台变化不大，有从南往北逐渐加大迹象，但是各台的年变化幅度又随时间而有较大差异。认为同时间里各台Z分量的变化差异，主要是各地长期变化速率不同引起的。认识了地磁场Z分量这些变化特征和规律，更好地发挥地磁手段在短临预报中的作用。

Electrical Characteristics of Tangjiawan Landslide in Lixian, Sichuan

A wide range of terrain features and landforms,which are exemplified by intricate geological formations and diverse rock compositions,are found in the western mountainous regions of China.These areas frequently encounter geological disasters.As one of the natural disasters,landslides lead to considerable loss of human life and property.Considering mitigation of the losses caused by landslide disasters,a necessary measure for disaster prevention and mitigation involves conducting detailed investigations and monitoring of landslides,which is also the cornerstone of landslide warning.This study compares and analyzes the feasibility of the magnetotelluric detection method for landslides using the results of engineering geological surveys and landslide monitoring.The study aims to address the scientific problem of the validity of using magnetotelluric methods to detect landslide development processes.The Tangjiawan landslide signal on the left side of the K94+000~K94+145 section of the Wenma Expressway is analyzed by employing engineering geological survey,magnetotelluric detection,landslide monitoring,landslide analysis,and other methods.Analysis results provide the static electrical characteristics of lithology,structure,and groundwater,as well as the dynamic electrical characteristics of landslide development.This study focuses on analyzing the relationship between the methods of magnetotelluric detection and engineering geological surveys and the results of landslide monitoring.The workflow and methods for data collection,processing,inversion,interpretation,and analysis using the magnetotelluric method to detect the dynamic development process of landslides are presented in the conclusion.Preliminary conclusions indicate a strong correlation between the dynamic changes in magnetotelluric wave impedance with the surface displacement of landslides and the dynamic changes in groundwater.The use of the magnetotelluric method for landslide detection and monitoring is a feasible example.The research results can offer certain technical references for the detection and monitoring of landslides using magnetotelluric methods and also provide references and guidance for the selection of diversified landslide monitoring methods in the future.

Characterization of Mediterranean Magnetotactic Bacteria

Magnetotactic bacteria are a diverse group of motile prokaryotes that are ubiquitous in aquatic habitats and cosmopolitan in distribution. In this study, we collected magnetotactic bacteria from the Mediterranean Sea. A remarkable diversity of morphotypes was observed, including multicellular types that seemed to differ from those previously found in North and South America. Another interesting organism was one with magnetosomes arranged in a six-stranded bundle which occupied one third of the cell width. The magnetosome bundle was evident even under optic microscopy. These cells were connected together and swam as a linear entire unit. Magnetosomes did not always align up to form a straight linear chain. A chain composed of rectangle magnetosomes bent at a posi- tion with an oval crystal. High resolution transmission electron microscopy analysis of the crystal at the pivotal position suggested uncompleted formation of the crystal. This is the first report of Mediterranean magnetotactic bacteria, which should be useful for studies of biogeochemical cycling and geohistory of the Mediterranean Sea.

Feasibility of using the magnetoteliuric method for sub-basalt imaging at Kachchh, India

The magnetotelluric （MT） method has been among the favorite supporting tools for seismic imaging of sub-salt and sub-basalt targets. In this paper we present an example from Kachchh, India （where basaltic rocks overlie Mesozoic sedimentary rocks）, and discuss the feasibility of using MT method as an exploration tool in this geological setting. Our results highlight the difference in magnetotelluric response caused by the thin intrabasalt layering. The key issue addressed in this paper is what MT can and cannot provide in such geological settings. First, we compute apparent resistivity and phase response curves using representative resistivity-depth models and borehole data from the study area. Later, we compare these results to assess the plausibility of using MT to image the sub-volcanic sediments at Kachchh. Finally, we substantiate our discussion through one-dimensional inversion of the field observed MT data from this region that exhibits poor sensitivity of MT for thin basalt layers.

The Application of the Acoustic Method to the Exploration of Urban Active Faults and a Comparison with the Artificial Earthquake, and Radar Methods

The depth of upper fault point is the key data for ascertaining the active age of a buried fault on a plain. The difference of depth obtained from same fault may be dozens to several hundred meters when using different geophysical methods. It can result in the absolutely opposite conclusions when judging fault activity. Because of a lack of an artificial earthquake source with wide band and high central frequency, many kinds of methods have to be used together. The higher the frequency of the artificial earthquake wave, electromagnetic wave and sonic wave, the higher the resolution. However the attenuation is also very fast and the exploration depth is very shallow. The reverse is also true. The frequency of artificial seismic waves is in the tens of Hz. Its exploration depth is big and the resolution is poor. The frequency of radar electromagnetic waves is about a million Hz, indicating that the resolving power is better, but the exploration depth is very shallow. However, the acoustic frequency is thousands of Hz, its resolving power is better than that of the artificial earthquake method and the exploration depth is larger than that of the radar method. So it is suitable for extra shallow exploration in the thick deposit strata of the Quaternary. The preliminary results detected using the high frequency acoustic method in extra shallow layers indicates that previous inferences about some fault activity in the eastern part of the North China plain may need to be greatly corrected.

Detection of UXO magnetic anomaly in Jinshan area

Magnetic survey is one of the most successful techniques for locating buried unexploded ordnances( UXO). For the location and identification of buried UXO in Jinshan area,a total-field magnetic survey is applied. The analytic signal of magnetic field is widely used to outline the boundaries of geology bodies,slightly dependent on the magnetization direction. In order to locate the UXO position,the analytic signal is applied to process the magnetic UXO data,which performs better than the conventional magnetic data. Then a typical UXO anomaly is extracted from the original data to invert for its depth by an improved Euler method proposed.The calculated depth is close to the real buried depth.

Recover vigorous cells of Magnetospirillum magneticum AMB-1 by capillary magnetic separation

Cultivable magnetotactic bacteria(MTB) in laboratory can provide sufficient samples for molecular microbiological and magnetic studies.However,a cold-stored MTB strain,such as Magnetospirillum magneticum AMB-1,often loses its ability to synthesize magnetosomes and consequently fails to sense the external magnetic field.It is therefore important to quickly recover vigorous bacteria cells that highly capable of magnetosome producing.In this study,a modified capillary magnetic separation system was designed to recover a deteriorating strain of Magnetospirillum magneticum AMB-1 that long-term cold-stored in a refrigerator.The results show that all cells obtained after a 3-cycle treatment were vigorous and had the ability to produce magnetosomes.Moreover,the 3rd-cycle recovered cells were able to form more magnetosome crystals.Compared with the colony formation method,this new method is time-saving,easily operated,and more efficient for recovering vigorous MTB cells.

Magnetic Signature of the Kusi Mineral Prospect, Papua New Guinea

A ground magnetic survey was conducted on the Kusi mineral prospect, Papua New Guinea, to provide insights into the magnetic properties of the mineralisation and help define drill targets for an exploration programme. The results of the survey suggest three distinct magnetic zones： （1） a magnetic high zone covering the northern portion of the survey area; （2） a northeast-southwest trending magnetic low zone occupying the southern portion and （3） a possible buried intrusive body separating the magnetic high from the low magnetic zone. The results of the survey suggest that drilling is concentrated on the zone of low magnetic response, and the periphery of the interpreted intrusion is adjacent to the contact to the limestone defining the mineralisation style of the two zones. A further ground magnetic survey is required to determine the western limits of the low magnetic zone.

Inverse Spline Interpolation for All-time Resistivity of Central-Loop TEM

A convenient numerical calculation method (inverse spline interpolation) for all-time apparent resistivity intransient electromagnetic method (TEM) is proposed in this paper. Characteristic of early and late normalized inductiveelectromotive force was investigated. According to the turning point, the transient process is divided into the earlyphase, the turning point, and the late phase. Afterwards, apparent resistivity is obtained through inverse spline interpo-lation in the early and the late phases, respectively. Finally, the resistivities of the early-time and the late-time wereconnected together by the turning point. The result shows that the inverse spline method is feasible and the method alsolays a foundation for initial model construction in the TEM automatic inversion.

The age measures and its layer sequence tratigraphy of Late Quaternary sediment in Lushan Dajiaochang of China

Through the scientific investigation on Lushan for a long time, detailed studies have been carried out on the geologic stratum section of Late Quaternary in Dajiaochang. The series age data of complete stratigraphic section and full time formation since 400 kaBP were based on the results of the analyses using the dating methods with various instruments such as the ancient geomagnetism, electronics spin resonance （ESR）, 36C1 and lumines- cence dating, etc. Corresponding to these data, it identified the paleomagnetic polarity events including Biwa- III event （320 kaBP）, Biwa- 1I event （260 kaBP）, Biwa- I event （180 kaBP, scarcity due to the disturbance of the iron dish）, Blake event （100 kaBP） and Laschamp event （20 kaBP, didn＇t grow due to the activities of the surface）, etc. Combined with the sequence stratigraphy, layer type characteristics and its sediment environment, the strati- graphic can be divided into 4 stages of development respectively ： Stage [ is the climate period of glacial epoch （200-400 kaBP）; stage 11 is the climate period of interglacial epoch （100-200 kaBP）; stage llI is the climate peri- od of periglacial epoch （10-100 kaBP）; stage IV is the climate period ofpostglacial epoch （0-10 kaBP）.

The metabolite profiling of coastal coccolithophorid species Pleurochrysis carterae(Haptophyta)

Pleurochrysis carterae is a calcifi ed coccolithophorid species that usually blooms in the coastal area and causes aquaculture losses. The cellular calcifi cation, blooming and many other critical species specifi c eco-physiological processes are closely related to various metabolic pathways. The purpose of this study is to apply the unbiased and non-destructive method of nuclear magnetic resonance(NMR) to detect the unknown holistic metabolite of P. carterae. The results show that NMR spectroscopic method is practical in the analysis of metabolites of phytoplankton. The metabolome of P. carterae was dominated by 26 metabolites involved in a number of dif ferent primary and secondary metabolic pathways. Organic acids and their derivatives, amino acids, sugars, nucleic aides were mainly detected. The abundant metabolites are that closely related to the process of cellular osmotic adjustment, which possibly refl ect the active ability of P. carterae to adapt to the versatile coastal niche. DMSP(dimethylsulphoniopropionate) was the most dominant metabolite in P. carterae, up to 2.065±0.278 mg/g lyophilized cells, followed by glutamate and lactose, the contents were 0.349±0.035 and 0.301±0.073 mg/g lyophilized cells respectively. Other metabolites that had the content ranged between 0.1–0.2 mg/g lyophilized cells were alanine, isethionate and arabinose. Amino acid(valine, phenylalanine, isoleucine, tyrosine), organic acid salts(lactate, succinate), scyllitol and uracil had content ranged from 0.01 to below 0.1 mg/g lyophilized cells. Trigonelline, fumarate and formate were detected in very low content(only thousandths of 1 mg per gram of lyophilized cells or below). Our results of the holistic metabolites of P. carterae are the basic references for the further studies when multiple problems will be addressed to this notorious blooming calcifying species.

Modeling of Earth Magnetic Field Disturbances Induced by Ferromagnetic Objects

This paper presents the methodology and results of modelling of Earth magnetic field disturbances induced by ferromagnetic objects. The modeling was carried out using the finite elements calculations, and the results were compared with the measurements. The special test stand, consisting of magnetovision scanner and Helmholtz coils, has been used. The measurement system is able to measure the distribution of planar magnetic induction vectors, and to differentiate the sources of measured disturbances.

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.

The state-of-the-art of the China Seismo-Electromagnetic Satellite mission

The China Seismo-Electromagnetic Satellite(CSES) mission was proposed in 2003 and approved in 2013 after ten years' scientific and engineering demonstrations. To meet the requirement of scientific objectives, the satellite is designed to be in a sunsynchronous orbit with an altitude of 507 km and descending node time of 14:00 LT. The CSES satellite carries 8 instruments,including search-coil magnetometer(SCM), electric field detector(EFD), high precision magnetometer(HPM), GNSS occultation receiver(GOR), plasma analyzer package(PAP), langmuir probe(LAP), high energetic particle package(HEPP) and detector(HEPD), and tri-band beacon(TBB), among which HEPD is provided by Italian Space Agency. The CSES satellite was launched successfully on February 2, 2018, and is planned to operate for 5 years. The CSES mission is the first satellite in China to measure geophysical fields, which will have a lot of application prospects in the study of seismology, geophysics, space sciences, and so on.

Progress in Studies of Geomagnetic Navigation of Animals

The geomagnetic field may play a key role in orientation and navigation of many long-distance mi- gratory animals. Taking homing and migrating birds as examples, this paper reviews recent progress in studies of geomagnetic "compass" of animals. Moreover, we propose to address two aspects in future geomagnetic orientation research :(1) what are the true components of the "map"? ( 2 ) What are the magneto-receptors and which brain areas acquire and process the geomagnetic field informa- tion ?

New understanding achieved from 2 years of Chinese ionospheric investigations

In the mainland of China, the number of ionospheric research groups is more than 10. Around 110 articles related to ionospheric physics have been published during 2014–2015. In this annual national report of the Committee on Space Research(COSPAR), we will outline some recent progresses in ionospheric studies conducted by the Chinese mainland scientists in the past 2 years. These investigations cover(1) the ionosphere responses to geomagnetic activities;(2) ionospheric climatology and structures;(3) couplings between the ionosphere, plasmasphere and lower atmosphere, and possible seismic signatures in the ionosphere;(4) ionospheric irregularities and scintillation;(5) ionospheric models, data assimilation and simulations;(6) ionospheric dynamics and electrodynamics;(7) progresses in the observation methodology and technique; and(8) planetary ionospheres. Such investigations will strengthen our ability to monitor the ionosphere,provide a better understanding of the ionospheric states and the underlying fundamental processes, and improve the ionospheric modeling, forecasting, and related applications.

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.