On the source of the quasi-Carrington Rotation periodic magnetic variations on the Martian surface: InSight observations and modeling

In a recent paper(Luo H et al.,2022),we found that the peak amplitudes of diurnal magnetic variations,measured during martian days(sols)at the InSight landing site,exhibited quasi Carrington-Rotation(qCR)periods at higher eigenmodes of the natural orthogonal components(NOC);these results were based on~664 sols of magnetic field measurements.However,the source of these periodic variations is still unknown.In this paper we introduce the neutral-wind driven ionospheric dynamo current model(e.g.,Lillis et al.,2019)to investigate the source.Four candidates-the draped IMF,electron density/plasma density,the neutral densities,and the electron temperature in the ionosphere with artificial qCR periodicity,are applied in the modeling to find the main factor likely to be causing the observed surface magnetic field variations that exhibit the same qCR periods.Results show that the electron density/plasma density,which controls the total conductivity in the dynamo region,appears to account for the greatest part of the surface qCR variations;its contribution reaches about 67.6%.The draped IMF,the neutral densities,and the electron temperature account,respectively,for only about 12.9%,10.3%,and 9.2%of the variations.Our study implies that the qCR magnetic variations on the Martian surface are due primarily to variations of the dynamo currents caused by the electron density variations.We suggest also that the timevarying fields with the qCR period could be used to probe the Martian interior's electrical conductivity structure to a depth of at least 700 km.

Multi-Barycenter Mechanics, N-Body Problem and Rotation of Galaxies and Stars

In the present paper, the establishment of a systematic multi-barycenter mechanics is based on the multi-particle mechanics. The new theory perfects the basic theoretical system of classical mechanics, which finds the law of mutual interaction between particle groups, reveals the limitations of Newton’s third law, discovers the principle of the intrinsic relationship between gravity and tidal force, reasonably interprets the origin and change laws for the rotation angular momentum of galaxies and stars and so on. By applying new theory, the multi-body problem can be transformed into a special two-body problem and for which an approximate solution method is proposed, the motion law of each particle can be roughly obtained.

Influence of the Earth's rotation on measurement of gravitational constant G with the time-of-swing method

In the measurement of the Newtonian gravitational constant G with the time-of-swing method,the influence of the Earth's rotation has been roughly estimated before,which is far beyond the current experimental precision.Here,we present a more complete theoretical modeling and assessment process.To figure out this effect,we use the relativistic Lagrangian expression to derive the motion equations of the torsion pendulum.With the correlation method and typical parameters,we estimate that the influence of the Earth's rotation on G measurement is far less than 1 ppm,which may need to be considered in the future high-accuracy experiments of determining the gravitational constant G.

Variational Principle of Instability of Atmospheric Motions

Problems of instability of rotating atmospheric motions are investigated by using nonlinear governing equations and the variational principle. The method suggested in this paper is universal for obtaining criteria of instability in all models with all possible basic flows. For example, the model can be barotropic or baroclinic, layer or continuous, quasi-geostrophic or primitive equations; the basic flow can be zonal or nonzonal, steady or unsteady.Although the basic flows possess a great deal of variety, they all are the stationary points in the functional space determined by an appropriate invariant functional. The basic flow is an unsteady one if the conservation of angular momentum is included in the associated functional.The second variation, linear or nonlinear, gives the criteria of instability. Especially, the general criteria of instability for unsteady basic flow, orographically disturbed flow as well as nongeostrophic flow are first obtained by the method described in this paper.It is also

THE INTERDECADAL VARIATION OF THE SOUTH ASIAN HIGH AND ITS ASSOCIATION WITH THE SEA SURFACE TEMPERATURE OF TROPICAL AND SUBTROPICAL REGIONS

This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role.

STUDY ON SENSITIVITY OF WIND FIELD VARIATION TO STRUCTURE AND DEVELOPMENT OF CONVECTIVE STORMS

In order to study the impacts of wind field variations in the middle and lower troposphere on the development and structure of storms,we carried out numerical experiments on cases of severe convection in the Jianghuai area under the background of cold vortex on April 28,2015.The results show that the structure and development of convective storms are highly sensitive to the changes of wind fields,and the adjustment of wind fields in the middle or lower troposphere will lead to significant changes in the development and structure of storms.When the wind field in the middle or lower troposphere is weakened,the development of convective storms attenuates to some extent compared with that in the control experiment,and the ways of attenuation in the two experiments are different.In the attenuation test of wind field at the middle level,convective storms obviously weaken at all stages in its development,while for the wind field at the low level,the convective storms weaken only in the initial stage of storm.On the contrary,the enhancement of the wind field in the middle or lower troposphere is conducive to the development of convection,especially the enhancement in the middle troposphere.In contrast,the convective storms develop rapidly in this test,as the most intensive one.The wind field variations have significant impacts on the structure and organization of the storm.The enhancement of wind field in the middle troposphere facilitates the intension of the middle-level rotation in convective storm,the reduction of the storm scale,and the organized evolution of convective storms.The strengthening of the wind field in the lower troposphere is conducive to the development of the low-level secondary circulation of the storm and the cyclonic vorticity at the middle and low levels on the inflowing side of the storms.

Rotation of the Earth as a Triaxial Rigid Body

The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated.

Investigation on variations of apparent stress in the region in and around the rupture volume preceding the occurrence of the 2021 Alaska MW8.2 earthquake

On July 29, 2021, a large earthquake of MW8.2 occurred south of the Alaska Peninsula. To investigate the spatial-temporal changes of crustal stress in the earthquake-stricken area before this event, we selected 159 earthquakes of 4.7 ≤ MW ≤ 6.9 that occurred in the epicentral region and its surroundings between January 1980 and June 2021 to study the temporal variation and spatial distribution of their apparent stress. In addition, we analyzed the correlation between seismic activities and Earth’s rotation and explored the seismogenic process of this earthquake. The crustal stress rose from January 2008 to December 2016. This period was followed by a sub-instability stage from January 2017 until the occurrence of the MW8.2 earthquake. The average rate of apparent stress change in the first five years of the stress increase period was roughly 2.3 times that in the last four years. The lateral distribution of the apparent stress shows that the areas with apparent stress greater than 1.0 MPa exhibited an expanding trend during the seismogenic process. The maximum apparent stress was located at the earthquake epicenter during the last four years. The distribution of the apparent stress in the E-W vertical cross section revealed that an apparent stress gap formed around the hypocenter during the first five years of the stress increase period, surrounded by areas of relatively high apparent stress. After the Alaska earthquake, most parts of this gap were filled in by aftershocks. The seismic activities during the sub-instability stage exhibited a significant correlation with Earth’s rotation.

Detection of different-time-scale signals in the length of day variation based on EEMD analysis technique

Scientists pay great attention to different-time-scale signals in the length of day(LOD)variations DLOD, which provide signatures of the Earth's interior structure, couplings among different layers, and potential excitations of ocean and atmosphere. In this study,based on the ensemble empirical mode decomposition(EEMD), we analyzed the latest time series of DLOD data spanning from January 1962 to March 2015. We observed the signals with periods and amplitudes of about 0.5 month and 0.19 ms, 1.0 month and 0.19 ms, 0.5 yr and 0.22 ms, 1.0 yr and 0.18 ms, 2.28 yr and 0.03 ms, 5.48 yr and 0.05 ms, respectively, in coincidence with the results of predecessors. In addition, some signals that were previously not definitely observed by predecessors were detected in this study, with periods and amplitudes of 9.13 d and 0.12 ms, 13.69 yr and 0.10 ms, respectively. The mechanisms of the LOD fluctuations of these two signals are still open.

Co-seismic Earth's rotation caused by the 2012 Sumatra earthquake

Earthquakes heavily deform the crust in the vicinity of the fault, which leads to mass redistribution in the earth interior. Then it will produce the change of the Earth's rotation (polar motion and length of day) due to the change of Earth inertial moment. This paper adopts the elastic dislocation to compute the co-seismic polar motion and variation in length of day (LOD) caused by the 2011 Sumatra earthquake. The Earth's rotational axis shifted about 1mas and this earthquake decreased the length of day of 1μs, indicating the tendency of earthquakes make the Earth rounder and to pull the mass toward the centre of the Earth. The result of variation in length of day is one order of magnitude smaller than the observed results that are available. We also compared the results of three fault models and find the co-seismic change is depended on the fault model.

THE THEORY OF RELATIVISTIC ANALYTICAL MECHANICS OF THE ROTATIONAL SYSTEMS

The theory of rotational relativistic mechanics is discussed and the theory ofrelativistic analytical mechanics of the rotational systems is constructed. Therelativistic generalized kinetic energy function for the rotational systemsand the generalized acceleration energy functionare constructed, and furthermore, the Hamiltonprinciple and three kinds of D’Alembert principles are given For the systems withholonomic constraints, the relativistic Lagrange equation.Nielsen equation, Appellequation and Hamilton canonical equation of the rotational systems are constructed,For the systems with nonholonomic constraints. the relativistic Routh equation,Chaplygin equation. Nielsen equation and Appell equation of the rototional systenisare constructed, the relativistic Noether conservation law of the rotational systems aregiven too.

Analysis of flow response to fluctuation of rotational speed in a radial impeller

By discretizing the convection terms with AUSM+-up scheme in the rotating coordinate system,a finite volume analysis code based on multi-block structured grids was developed independently so as to realize the numerical solving of internal flow fields of turbomachineries.Taking an unshrouded radial impeller with the working fluid of water vapour as the research object,the flow response to the fluctuation of rotational speed was calculated.By comparing the surface pressure profiles and velocity contours calculated by the code and commercial software respectively,the accuracy of flow solver was verified.The analysis of flow response data indicates that,as the working condition shifts closer towards the surge boundary,the response of flow parameters such as mass flow and aerodynamic torque will be more nonsynchronous with the fluctuation of rotational speed,and also the influence of density variation on mass flow variation will be smaller.Moreover,the transient variation region of working condition performance will deviate farther away from the steady performance curve as the working condition approaches the surge boundary.Compared to the working conditions with small mass flows,the distribution characteristics of pressure difference load on the blade surface vary little under large mass flow conditions.The reduction of fluctuation amplitude of rotational speed exerts no influence on abating the hysteresis of flow response.

Remarks about External Forces Acting on Earth’s Rotation Axis

It is well known that a variation in the direction of Earth’s rotation axis is a real astronomical phenomenon, named nutation. It is interesting if a variation of this axis can take place only in intensity, in the simplest theoretical case of only two rigid body dynamics. This paper presents two positions of the Moon during its monthly orbit, where a sudden variation of Earth’s rotation axis in intensity can take place. The duration of this phenomenon is limited in time, maybe an instant or a day, and then a vortex can appear.

基于旋转变分模态分解的IMU角速度去噪算法

惯性测量单元(IMU)的应用中,角速度的噪声误差积累对姿态解算性能有较大的影响。针对角速度中存在的噪声,提出一种融合了变分模态分解(VMD)和角速度旋转三维分解的去噪算法。首先通过坐标系旋转获得角速度在不同虚拟轴的输出,再利用VMD提取合适分量重构虚拟轴信号。VMD的非线性重构使得各个虚拟轴的残留误差相对独立,最终多个虚拟轴的反向旋转回到原始坐标系后通过独立信号的均值合并能有效消除IMU中角速度的噪声。基于EuRoC数据集的实验结果表明:该算法降噪效果显著,均方根误差降低70%~85%,且能有效平衡三轴误差。

Earth: Review Article

Every year on 22 April, we have celebrated Earth Day and the beautiful planet we call home. Earth Day, established in 1970, has been used to highlight our planet’s environmental challenges and raise awareness of the importance of protecting our world for future generations [1]. To provide the protection of our planet, we should explain Earth’s environmental challenges to the best of our knowledge in frames of contemporary Geophysics. This paper gives a short overview of the developed Hypersphere World-Universe Model (WUM) and pay particular attention to the principal role of Dark Matter (DM) in the Earth’s life. In this manuscript, we discuss different aspects of the Earth: a condition of Young Earth before the Beginning of life on It;Internal Structure;“The 660-km Boundary” that we named Geomagma;Random Variations of Earth’s Rotational Speed on a daily basis;Origin of Moon;Expanding Earth;Internal Heating;Faint Young Sun paradox;Geocorona and Planetary Coronas;High-Energy Atmospheric Physics. WUM proposed principally different ways to solve the problems of Internal Heating, Origin of the Moon, and Faint Young Sun paradox based on DM core of the Earth. The Model revealed the fact that the Sun Activity causes the Geomagma Activity and, as a consequence, Random Variations of Earth’s Rotational Speed by the varying Sun’s magnetic field.

基于AVMD与DPC-FCM的旋转机械无监督故障诊断方法

目的 针对旋转机械故障诊断过程中存在故障信号特征提取困难、故障诊断过程有标签数据较少、故障诊断准确率低等问题,提出自适应变分模态分解算法(Adaptive Variational Mode Decomposition,AVMD)与密度峰值算法优化的模糊C均值算法(Clustering by Fast Search and Find of Density Peaks Optimizing Fuzzy C-Means,DPC-FCM)结合的无监督诊断方法。方法 首先,将多尺度排列熵与峭度相结合的综合系数作为适应度函数,对VMD算法的惩罚因子alpha和模态个数K进行参数寻优,提取分解后本征模态函数(Intrinsic Mode Function,IMF)的平均样本熵与平均模糊熵,并输入至聚类算法中。其次,提出利用密度峰值聚类算法确定FCM的初始聚类中心,降低聚类结果的随机性。结果 将提出的无监督故障诊断模型应用到滚动轴承试验信号中,实现了准确的故障诊断。结论 AVMD在故障提取方面具有优越性,同时DPC算法可以有效提高FCM算法无监督聚类的准确性,二者结合可以有效实现旋转机械故障的智能分类。

Earth’s rotation-triggered earthquakes before the 2018 M_S5.7 Xingwen earthquake

For earthquakes(ML≥2.0) that occurred from January 2006 to October 2018 around the Ms5.7 Xingwen earthquake occurred on 16 December 2018 in Xingwen,Sichuan province,China,we statistically investigated the correlation between the phase of Earth's rotation and the occurrence of earthquakes via Schuster's test to determine the signals that triggered earthquakes before the Ms5.7 Xingwen event.The results were evaluated based on the P-value where a smaller P-value corresponded to a higher correlation between the occurrence of an earthquake and Earth's rotation.We investigated the spatial distribution of Pvalues in the region around the epicenter of the Ms5.7 Xingwen event,and obtained a result exhibiting a extremely low-P-value region.The松5.7 event occurred inside near the northern boundary of this region.Furthermore,we analyzed the temporal evolution of P-values for earthquakes that occurred within the extremely low-P-value region and found that some extremely low P-values(less that 0.1%),i.e.,significant correlation,were calculated for earthquakes that occurred before the胚5.7 Xingwen earthquake.Among sixty・one earthquakes with the lowest P-value,occurred from May 2014 to April 2018,a vast majority of them occurred during the acceleration of Earth's rotation.The lower P-value obtained in this study reveals that the Xingwen source body probably was extremely unstable prior to the occurrence of the Ms5.7 Xingwen earthquake.

Changes and determining factors of crop evapotranspiration derived from satellite-based dual crop coefficients in North China Plain

Evaluating actual crop evapotranspiration(ET) variations and their determining factors under changing climates is crucial for agricultural irrigation management and crop productivity improvement in nonhumid regions.This study analyzed the spatiotemporal characteristics and detected the determining factors of ETfor winter wheat and summer maize rotation system from 2000 to 2017 in the North China Plain(NCP),by combining the FAO-56 dual crop coefficient approach with remotely sensed vegetation indices(VIs).The results indicated that daily air temperature increased in varying degrees while wind speed and sunshine hours decreased slightly during the growing season of winter wheat and summer maize over the study period.The trends of relative humidity and effective precipitation varied in crop growing seasons.Based on the validated relationship of dual crop coefficients and VIs,the estimated multi-year average ETof winter wheat(370.29±31.28 mm) was much higher than summer maize(281.85±20.14 mm),and the rotation cycle was 652.43±27.67 mm.Annual ETof winter wheat and the rotation cycle increased by 2.96 mm aand 1,77 mm a,respectively.However,the ETof summer maize decreased with distinct spatial variation.Spatially,winter wheat ETincreased significantly in the northeast NCP,covering the Beijing-Tianiin-Hebei areas.Meanwhile,significant increases in summer maize ETwere detected in the southwest NCP.The sensitivity and contribution analysis showed that ETof winter wheat and summer maize was positively sensitive to temperature,wind speed,and sunshine hours while negatively to relative humidity.Moreover,wind speed and sunshine hours contributed most to changes in ET(around 20%-40%).

Atmospheric Excitation of Time Variable Length-of-Day on Seasonal Scales

我们使用小浪变换的方法分析 EOP (IERS ) C04 的地球的旋转率的时间系列。结果表演季节(年度、一年两次) length-of-day (LOD ) 的变化在它的时期长度和振幅有时间的可变性。在 1965.02001.0 期间，一年两次、年度的部件的时期从主要变化了对 175 天 190 天并且从对 360 天 370 天分别地；当他们的振幅分别地由超过 0.2 ms 和 0.1 ms 变化了时。在这个时期期间分析大气的尖动量(AAM ) 的轴的部件，我们发现了时期长度和振幅的时间变化也在轴的 AAM 的季节的摆动存在并且在有季节的 LOD 变化的那些的好一致性。轴的 AAM 的时间变化能大部分在季节的规模上解释 LOD 的变化。

Real-time rapid prediction of variations of Earth's rotational rate

Real-time rapid prediction of variations of the Earth's rotational rate is of great scientific and practical importance. However, due to the complicated time-variable characteristics of variations of the Earth's rotational rate (i.e., length of day, LOD), it is usually difficult to obtain satisfactory predictions by con-ventional linear time series analysis methods. This study employs the nonlinear artificial neural net-works (ANN) to predict the LOD variations. The topology of the ANN model is determined by minimizing the root mean square errors (RMSE) of the predictions. Considering the close relationships between the LOD variations and the atmospheric circulation movement, the operational prediction series of axial atmospheric angular momentum (AAM) is incorporated into the ANN model as an additional input in the real-time rapid prediction of LOD variations with 1-5 days ahead. The results show that the LOD pre-diction is significantly improved after introducing the operational prediction series of AAM into the ANN model.