成都地磁台墩差、方位角的测量与评估

通过系统整理成都地磁台墩差及天文方位角的观测资料,对测量仪器比测方法、观测人员、测量精度等方面进行分析评估,提出了本项工作的主要技术成果,并以便查表的形式给出了成都台新旧观测室等11个仪器观测墩相互间的F、I、D、H、Z各地磁要素的墩差,以及各墩与目标、标志的方向角、方位角。本文还从另一方面证明了成都地磁台良好的观测技术条件和稳定的观测质量,这些资料对于台站标准化,数字化都是有重要意义的。     

满洲里地磁台墩差与仪器差检验

讨论了满洲里地磁台墩差与仪器差检验的必要性,实施的方法步骤及所取得的成果,并给出了D,I,F,H,Z等要素的仪器差及墩差的校正公式.文章明确指出,凡需要更换仪器或墩位的台站,在此前后均须进行仪器对比观测和墩差测定,以保证观测数据的长期衔接.文章首次指出,为监视记录仪、记录墩的长期稳定性,一个标准地磁台不仅要测定绝对观测室内各墩位间的墩差,还须测定记录墩和观测墩之间的墩差.     

大连地磁台天文方位角测量

论述大连地磁台天文方位角的测量原理、方法及观测结果,在地磁观测室未封顶的条件下,能在观测墩直接观测北极星,避免比测墩转角换算等因素增加的观测误差,观测精度提高.     

兰州地磁台GPS差分方位角的测量

为了适应高采样率、高分辨率、高精度的新型地磁仪器对磁偏角和磁倾角观测的需要,应用GPS测定了改造后的兰州地磁台的7个观测墩（一个临时观测墩）至2个方位标志的方位角,共取得了13个方位角参数,使兰州地磁台在地磁偏角测量或仪器验收比测中可供6套仪器同时观测,并可做到全天候观测。     

蒙城地磁台测量标志方位角测定

采用差分GPS和高精度水平角观测技术,精确测定蒙城地震台2个室内观测墩至7个室外观测标志的方位角,获取14个方位角参数,观测精度符合地磁技术规范要求。     

乌鲁木齐地磁台标志方位角的测定

介绍了乌鲁木齐地磁台测量标志方位角的方案、测量方法、原理。利用已有的观测成果,采用几何转换的方法精密测量了新建成观测室内的6个观洲墩相对于2个方位标志的方位角,成功的将旧观测室原标准墩方位角数据迁移到新观测室内各观测墩上,观测精度符合技术规范的要求,使新观测设施能够及时投入到观测工作中。并对地磁观测环境改造完成后的全面测量工作作出规划,在知识、技术上都做好了准备。     

德都台地磁观测与温度影响关系的分析

选用德都台2011—2012年的地磁基线值数据,来分析绝对观测数据、相对记录数据和温度数据对基线值的影响。通常基线值的主要影响因素除温度外,还与人为观测误差、湿度和记录墩的稳定性有关。首先保证绝对观测固定为同一人员,确保人为观测误差忽略不计,再排除湿度与记录墩的不稳定性,最后利用回归分析计算方法,得到基线值数据与温度数据的回归方程,并对该方程进行显著性检验,表明地磁基线值与温度之间存在良好的线性关系,再以此回归方程来判断我台地磁数据的好坏,为更好的改进我台地磁观测数据质量提供依据。     

杭州地磁台方位角的复测检验

通过实际观测,描述了杭州地磁台方位角的检验结果,通过复测检验有两点认识:一种新技术新方法的应用,须经过不同方法的严格比较检验,验收合格后方可推广应用;如果采用简接法测定观测墩的方位角,其精度不完全决定于天文或GPS的观测精度,在很大程度上取决于水平角的观测精度.为此建议用此法测定观测墩的方位角,须有合理的观测程序和严密的观测技术,与此同时,尚须具备高于方位角精度要求的高精度精密光学经纬仪.     

嘉峪关地磁台墩差测量与仪器比测

墩差测量和仪器比测是地磁观测中最基本的工作，直接影响到观测资料的质量和使用价值。近年的研究结果表明，震磁异常通常为几nT至几十nT。因此，提高观测数据的准确性对地磁预报地震具有深远意义。对嘉峪关地磁台仪器比测和墩差测量的方法及结果作了简要总结，供兄弟台站借鉴（文中所用的比测数据和墩差测量数据是北京台传递的标准结果）。     

地磁仪器墩材料的选择

选择无磁性或弱磁性材料建筑仪器墩是建筑一个好的地磁房,特别是观测室的关键。陕西省乾县地磁台原先采用石灰石、水泥、沙子混凝土块作为仪器墩材料,磁性基本合乎要求,但施工结束后发现,墩面及墩上梯度较大。后换成纯石灰石条块砌筑的仪器墩。情况明显好转。因此。根据我们的体会,在有条件的地方观测仪器墩最好采用磁性较小的纯石灰石条块建筑。     

On the synchronism in the events within the core and on the surface of the earth: the changes in the organic world and in the polarity of the geomagnetic field in the phanerozoic

The data on geomagnetic reversals are compared with the changes in the organic world and with the lower-mantle plumes. The times of the formation of plumes and the times of their appearance on the Earth’s surface relate to the intervals characterized by the different frequencies of geomagnetic reversals, i.e., there is no interrelation between the formation of plumes and the frequency of the changes in the geomagnetic field polarity. At the same time, a certain synchronism is observed between the frequency of the geomagnetic reversals and the boundaries of the biostratigraphic ages, i.e., the changes in the organic world in the long-period range. A hypothesis is proposed, which explains the change in the sign of the geomagnetic field by the combined effect of the irregular rotation of the internal core relative to the mantle and the changes in the slope angle of the axis of the Earth’s rotation, which, in turn, results in synchronous events on the Earth’s surface: the rates of changes in the organic world.     

On the maintenance of the axisymmetric part of the flow in the atmosphere

Summary The maintenance of the axisymmetric component of the flow in the atmosphere is investigated by means of a steady-state, quasi-geostrophic formulation of the meteorological equations. It is shown that the meridional variations in the time-averaged axisymmetric variables can be expressed as the sum of three contributions, one being due to the eddy heat transport, another to the eddy momentum transport, and a third to the convective-radiative equilibrium temperature which enters the problem through the specification of a Newtonian form of diabatic heating. The contributions by the large scale eddies are evaluated through the use of observed values for the eddy heat and momentum transports.The contributions from each of the three forcing mechanisms to the temperature and zonal wind fields are invstigated individually and found to be of about equal importance. The sum of the three contributions are also presented for the temperature, the zonal wind, the stream function associated with the mean meridional circulation and the corresponding vertical motion. Although the results fail to reproduce the main observed features of the lower stratosphere, they are found to be in good agreement with observations in the middle latitude troposphere. At any pressure level, for example, the computed mean zonal wind has a jet-like profile and the axis of the jet is found to slope to the south with height, as observed in the atmosphere.Based in part on a thesis submitted by the first author as partial fulfillment of the requirements for the Ph.D. degree at the University of Michigan. — Publication No. 194 from the Department of Meteorology and Oceanography, The University of Michigan.     

On the gravimetric undulations of the geoid and the deflections of the vertical

Summary The author mentions the aims of the World-wide gravity project he established in the Ohio State University in Columbus, in 1950. He outlines the practical procedure of the gravimetric computations of the undulationsN and the vertical deflection components and and emphasizes that only by the global international cooperation and additional gravity observations at sea carried out during the last decade it has been possible to gather to Columbus the needed gravity material. Since there exist still large gravimetrically unsurveyed areas it is of vital significance to study what gravity anomalies are best to be used for these regions. The given figures concerning the accuracy of theN, and , estimated theoretically and obtained in practice, indicate that in the gravimetrically well surveyed parts of the world like in Europe and the United States we can get gravimetrically on basis of existing gravity material theN-values with accuracy of about 5–10 meters, and and with the accuracy of about 1. The geoid undulationsN are already computed in Columbus for more than 6000 points of the northern hemisphere. The sample maps show the interesting geoid of Europe and vicinity between the latitudes 60° and 30° and longitude 5° W and 30° E, drafted on basis of more than 1000N-values computed at the corners of 1°×1° squares. It is interesting to realize that the geoid undulations in all this area are positive, the extreme values being between 40 and 50 meters. The geophysical significance of the geoid maps of this kind is pointed out.     

太平洋中部地磁台11年周期变化的研究

综合APIA、HONOLULU、PAMATAI 3个地磁台三分量的11年周期变化的形态后,可定性地提出该变化源于内场。如内源为核幔边界的电涡流,则其中心点应位于3台之间。     

On the variation in the geomagnetic dipole over the geological history of the Earth

The global database on the paleointensity, containing determinations of the virtual dipole moment (VDM) for a stable (normal) regime of the geomagnetic field in a time interval of up to 3.5 Ga, is supplemented by new VDM determinations and analyzed. The field generation process started no later than 3–3.5 Ga (earlier data are absent) at the stage of the Earth’s core formation. Since that time, the dipole value has differed from its present value by no more than an order of magnitude, and the deviations that have already been detected tend toward smaller values. The distribution of VDM values in the time interval 0–400 Ma is bimodal, which apparently reflects the presence of two different generation levels of the geomagnetic field distinguished by a relatively large value (close to the present field value) and a relatively small value (approximately half as large as the present value). The total duration of decreased VDM values appreciably exceeds that of increased VDM values (179.1 and 28.6 Myr, respectively). On the whole, data on the paleointensity do not contradict the hypothesis about the dipole nature of the field over the last 400 Myr; however, the number of determinations at high paleolatitudes is too small to draw decisive conclusions on the validity (or invalidity) of the dipole field approximation based solely on paleointensity data.     

Magnetic stratigraphy of the Ordovician in the lower reach of the Kotuy River: the age of the Bysy-Yuryakh stratum and the rate of geomagnetic reversals on the eve of the superchron

Until recently, the existing data prevented the geophysicists from accurately dating the Bysy-Yuryakh stratum, which outcrops in the middle reach of the Kotuy River, constraining the time of its formation to a wide interval from the end of the Late Cambrian to the beginning of the Silurian. The obtained paleomagnetic data unambiguously correlate the Bysy-Yuryakh stratum to the Nyaian regional stage and constrain its formation, at least a considerable part of it, by the Tremadocian. This result perfectly agrees with the data on the Bysy-Yuryakh conodonts studied in this work and yields a spectacular example of the successful application of paleomagnetic studies in solving important tasks of stratigraphy and, correspondingly, petroleum geology. Within the Bysy-Yuryakh stratum, we revealed a large normal-polarity interval corresponding to the long (>1 Ma) period when the geomagnetic reversals were absent. This result, in combination with the data for the Tremadocian and Middle–Upper Cambrian sequences of the other regions, indicates that (1) the rate of occurrence of the geomagnetic reversals on the eve of the Ordovician Moyero superchron of reversed polarity was at most one reversal per Ma; (2) the superchron does not switch on instantaneously but is preceded by a certain gradual change in the operation conditions of the dynamo mechanism which, inter alia, manifests itself by the reduction of the frequency of geomagnetic reversals with the approach of the superchron. This finding supports the views according to which a process preparing the establishment of the superchrons takes place at the core–mantle boundary.     

Comparison Between the Nutations of the Planet Mars and the Nutations of the Earth

The nutations of the planets Mars andEarth are investigated and compared. Alarge number of interior structureparameters are involved in the nutationcomputations. The comparison between the observations and the computationsprovides several constraints on these parmeters andtherefore allows a better understanding of the physics of the interior of theplanet. For the Earth, the high precision of the observations of the nutationshas led to a very good determination of interior properties of the planet. ForMars, observations of nutations are not yet available, and we review how theamplitude of the Martian nutations depends on the hypotheses consideredfor its interior. Although Mars is very similar to the Earth, its interior is not well known;for example, we don't knowif its core is liquid or solid. Only if the core is liquid,the Free Core Nutation (FCN) normal mode exists and can alter the nutationswhich are close to the resonance. From the observed geoids, it is known thatboth planets are not in hydrostatic equilibrium. The departure is larger forMars than for the Earth, and consequently, the implication of considering a convective mantle instead of a mantle in hydrostatic equilibrium described byClairaut's equation for the initial equilibrium state of the planet is largeron the Martian nutations than on the Earth nutations. The consequences of theuncertainty in the core dimensions are also examined and shown to be of a veryhigh influence for Mars if the core is liquid, due to the potential changes inthe FCN resonance. The influence of the presence of an inner core, which isknown to exist for the Earth, could be more important for Mars than for theEarth if the inner core is large. Due to the presence of Tharsis on Mars, thetriaxiality of this planet has, additionally, larger effects than on Earth.     

Evolutionary Changes in the Configuration of the Magnetic Field of the Solar Corona in the Epoch of the Minimum

Geomagnetism and Aeronomy - The evolution of the magnetic configuration in the solar corona is studied. The curvature of the K-corona helmets obtained from an analytical approximation of the...