On reconstruction of the Ito-like equation from persistent time series

The Langevin equation with finite-range persistence was introduced as a macroscopic model of various geophysical phenomena. The modified histogram procedure (MHP) of reconstruction of the equation from time series was proposed. An efficiency of MHP was tested on artificial persistent time series (with short and long-tail distributions) generated by different Ito-like equations. For an exemplary geophysical time series, the appropriate Ito-like equation was reconstructed.     

地震前兆观测资料的分形处理方法

本文从自仿射分形的角度探讨地震兆汾观测资料的分形处理方法。在对自仿射分形的分维量测方法进行对比分析的基础上，给出了处理地震前兆观测资料较为适用的分形方法和满足计算需要的样本点数，从对部分水氡和地电阻率资料进行了处理分析中，得到了有益的启示：地震前兆时序观测资料可用分形方法处理分析，分维值可反映观测资料的结构变化特征，其作为一个无量纲量为综合对比分析各类前兆现象，探讨地震前兆场的复杂性特征提供了有效     

Auroral fading structure before breakup: A review

This review is devoted to auroral fading before beginning of the substorm active phase. This initial stage of the active phase called breakup is accompanied by a sharp brightening of auroras and their rush toward the pole. Auroral fading before breakup was first detected in discrete auroras in the nightside sector and consisted in that a short-term decrease in brightness of an arc moving toward the equator below the level observed during the preliminary phase was observed during the substorm preliminary phase 2–3 min before breakup. During fading, the velocity of equatorward motion of auroral arcs decreased up to their complete stoppage. Auroral fading in the noon sector was registered simultaneously with fading on the Earth’s nightside before the beginning of the active phase. Short-term background fading was also observed both equatorward and poleward of an arc on the nightside. It was subsequently indicated that similar fading is observed in various geophysical phenomena. It was detected that a radar aurora signal fades before breakup, if auroral substorm is observed in a radar pattern and substorm source is located under good aspect conditions. Riometer absorption decreases simultaneously with auroral fading. Geomagnetic pulsations decay on dayside and nightside immediately before breakup. Such a multiform manifestation of fading in various geophysical phenomena indicates that fading is related to some global processes proceeding in the magnetosphere when energy accumulation in this region comes to the end before its explosive release into the polar ionosphere.     

Diversity of threshold phenomena in geophysical media

The sample analysis of threshold phenomena in the lithosphere, atmosphere, and magnetosphere is conducted. The phenomena due to the flow of electric current and pore fluid in the rocks are considered, the scenario of wind-driven generation of atmospheric electricity is suggested, and the model of the geomagnetic storm time Dst variation is analyzed. An important general conclusion consists in the fact that in the geophysical media there is a wide class of threshold phenomena that are affine with phase transitions of the second kind. These phenomena are also related to the critical transitions in self-oscillatory systems with soft self-excitation. The integral representation of bifurcation diagrams for threshold phenomena is suggested. This provides a simple way to take into account the influence of the fluctuations on the transition of a system through the threshold. Fluctuations remove singularity at the threshold point and, generally, lead to a certain shifting of the threshold. The question concerning the hard transition through the threshold and several aspects of modeling the blow-up instability which is presumed to occasionally develop in the geophysical media are discussed.     

GPS坐标时间序列中非构造噪声的剔除方法研究进展

GPS台站坐标解算中包含多种地球物理参量造成的不确定性、系统误差和随机噪声.回顾了GPS台站坐标噪声分析的研究进展,包括功率谱分析、最大似然估计、区域叠加滤波、主成分变换以及质量负荷下的地壳弹性形变模拟等,并讨论了各种方法在分析噪声的类型和强度、共模误差(common-mode errors)的物理起源等方面的作用及局限性,展望了下一阶段的研究思路.     

地震地球物理监测数据各库数据差异原因

笔者在工作中发现,使用地震台站、区域地球物理台网、国家台网地震地球物理监测数据库中同一台站、同一测项、相同时段监测数据绘制曲线,存在曲线不一致现象,分析认为,存在差异的原因主要是,数据经审核、反馈、处理,再次上传各库过程中未及时核对、及时发现、及时覆盖,省地震局区域地球物理台网需定时检查、同步各库数据。     

DQ-87型地球物理数据采集和处理系统

在地球物理学领域内经常遇到各种观测资料,其信号频率范围属于甚低频和超低频。例如地磁脉动,由电离层反射的无线电波频率的多普勒偏移,哨声,声重力波以及一般的地磁、地电、地震资料,大气参量的变化及其湍动等等,它们的频率范围从千分之几赫兹到数千赫兹。这些资料的收集和整理通常是分开的,由于记录的资料通常并不是数据化的,     

Variations of solar radiation input to the lower atmosphere associated with different helio/geophysical factors

The influence of helio/geophysical factors on the solar energy input to the lower atmosphere has been studied at the network of actinometric stations of Russia in different latitudinal belts. It was found that there are appreciable changes in the half-yearly values of total radiation associated with galactic cosmic ray (GCR) variations in the 11-yr solar cycle, the increase of GCR flux being accompanied by a decrease of the total radiation at higher latitudes and by its increase at lower latitudes. Auroral phenomena and solar flare activity are likely to affect the solar radiation input to the high-latitudinal belt together with GCR variations, the increase of both these factors resulting in the decrease of total radiation. The changes found in the total radiation fluxes in the lower atmosphere seem to be related to the cloud cover variations associated with the solar and geophysical phenomena under study. The variations of the solar radiation input in the 11-yr-cycle amounting to ±4–6% may be an important factor affecting tropospheric dynamics.     

Rift tectonics development in the light of geophysical data: Red sea region

Summary The paper discusses geophysical phenomena observed over tholeiitic dykes detected in the Eastern Desert of Egypt (Nubian Block). The dykes show specific physical properties and are either normally or reversely polarized along their whole length over 120 km. Dykes of similar properties may also be interpreted from airborne geophysical maps in Saudi Arabia (Arabian Block). Magnetic fields of the tholeiitic dykes were interpreted quantitatively: they fit the magnetic pattern over the Red Sea. The study emphasizes those geophysical phenomena which may serve as criteria for recognition of regions with rift tectonics development.     

Discreteness of spatial-temporal manifestations of solar activity and solar-terrestrial phenomena

The discreteness of the time series of the solar-related geophysical phenomena is justified. The balance of the formation and decomposition (neglecting diffusion) of fractal elements during the evolution of the equilibrium systems as applied to the heliophysical and geomagnetic phenomena is the original position in this case. The discreteness properties of the spatial-temporal characteristics of solar activity are simply justified based on a fractal analysis. The performed calculations in the solar wind medium in the near-Earth space make it possible to classify the fluxes depending on their fractal dimension. The possible mechanism by which high-speed solar wind streams are generated is also briefly discussed in the scope of the fractal paradigm.     

On the reconstruction of Ito models on the basis of time series with long-tail distributions

Two methods of reconstruction of Ito equations on the basis of time series were analysed. The Sequin method appeared to be completely inadequate in cases of considerable noise. The histogram method required some improvements; therefore, the procedure of smoothing of joint distribution function was proposed and verified. Ito equations may constitute some macroscopic models of phenomena in which microscopic interactions are averaged in an adequate way. Analysis of two geophysical phenomena is presented. For these two examples, Ito equations are constructed and some physical causes of resulting forms of the deterministic and stochastic force are deduced.     

地球自转速率变化及其与地球物理现象关系研究的进展

作为地球的基本运动形式之一的地球自转变化表征着地球的整体运动状态和地球系统各圈层之间的相互作用过程,其变化形式非常复杂．研究表明,地球自转速率的变化与众多地球物理现象有密切联系,与地震活动、EN-SO事件等重大自然灾害存在一定的相关性．因此,对地球自转速率变化及其与地球物理现象之间关系的研究长期以来就受到天文学家、地球科学家和从事灾害研究领域专家的重视．本文主要介绍了该研究领域近年来的研究进展,并认为在此基础上开展更深入的研究对天文学和地球科学的发展都是有意义的．     

地球物理信号能量(密度)多维分形及应用

地球物理信号代表的地质地球物理过程在多种尺度上和尺度之间表现为自相似性（self-affinity)或尺度无关性（Scale Invariant)，称为地球物理信号的分形性质，多个分形地球物理信号叠加在一起表现为多维分形特征，研究多维分形地球物理信号的能量或能量密度特征，可以进行时间或空间地球物理信号的校正、奇异性研究分析，或进行不同地球物理动力学过程的分解，本文描述了地球物理时间（空间）信号的多维分形过程和功率谱密度（能量密度）与波数以及重磁场能谱密度及面积（能量）与能谱密度的多维分形关系，并用地球物理测井与重磁资料作了试算。     

地磁低点位移现象及其与地震的关系

本文用中国地磁台网多年的资料,研究了地磁垂直分量日变极小值出现的时间(低点时间)在空间分布的异常特征,即低点位移现象。这种少见的地磁异常现象与地震的发生有较好的相关性,其发震日期为异常日以后的第27天或41天前后4天,发震地区在低点位移突变分界线附近。低点位移是一种复杂的地球物理现象,受多种因素影响,其机制仍处在探索阶段。      

地震预测的物理基础与可能性

地震不是随机发生的，在地震发生之前，震源区存在介质弹性减弱，密度减小，体积膨胀的孕震过程，它将引起各种地球物理方法的前兆观测手段出现形形色色的变化，只要坚持实践－研究－再实践，反复不断地加深规律认识，不断地积累探索，就能循着渐进式预测之路，逐渐实现地震预测。     

Visibility graph analysis of geophysical time series: Potentials and possible pitfalls

Recently, complex network approaches to time series analysis have been developed and successfully applied to geophysical records. In this paper, the visibility graph approach is re-considered, which has been found useful as an alternative tool for describing the fractal properties of a time series. The interpretation of various graph-theoretical measures in the context of visibility graphs, their mutual interdependence, and their sensitivity in the presence of missing values and uncertainties (posing typical challenges in geophysical time series analysis) are thoroughly discussed. The obtained results are illustrated for some exemplary records from different fields of geosciences.     

Long-term solar activity and terrestrial connections. Part II: at the beckon of the sun?

The research task described herein aims at the structuring of an analytical tool that traces the time course of geophysical phenomena, regional or global, and compares it to the course of long-term solar conditions, long-term meaning decades or a few centuries. The model is based on the premise that since in a last analysis the preponderance of atmospheric, hydrospheric, and, possibly, some aspects of geospheric phenomena are, or have been, powered by energy issuing from the sun – either now or in the past – the long-term behavior of such phenomena is ultimately connected to long-term changes occurring in the sun itself. Accordingly, the proposed research firstly derives and models a stable surrogate pattern for the long-term solar activity, secondly introduces a transfer-function algorithm for modeling the connection between the surrogate and terrestrial phenomena viewed as partners in the connection, and thirdly probes the connection outcome for episodic or unanticipated effects that may arise due to the fact that in the present context, the connection, should it exist, is very likely nonlinear. Part I of the study presents the theory of the concept, while Part II demonstrates the concepts pertinence to a number of terrestrial phenomena.     

Interdependent perturbations of the Earth’s surface, atmosphere, and ionosphere

The results of original experiments performed with a ground-based geophysical laser interferometer and a GPS-based satellite ionospheric profilometer are given. Synchronous growth was recorded for deformations of the Earth’s surface and variations in the atmospheric pressure and in the level of spatiotemporal modifications of the electron content within the ionospheric F2 layer with characteristic space scales of 10²–10³ km and periods of 10²–10³ s. The relationship between the revealed phenomena and the Earth’s seismic activity is analyzed.