关于钱德勒章动的探讨

本文从地球在太阳系内的自转和公转运行规律及太阳与地球之间的动量交换机制,来探讨地极的移动。为此,作者引出了光压矩和光压冲量矩的概念。在地球的自转和公转运动中,由于赤黄交角的存在和地球北南半球陆地表面积分布的不平衡性,在太阳光压的作用下,北南半球相对赤道产生不相等的光压矩,从而使原来平衡的以地心为支点的自转轴两端分别施加了周期性的外力,导致自转轴的晃动,产生极移。本文计算了(1)二分点(日)及二至点(日)地球北南半球相对赤道产生的较差光压冲量矩的大小,即极移的激发量级;(2)夏至点(日)和冬至点(日)地球北南半球相对赤道产生的光压矩及光压冲量矩呈反向变化,即极移振幅衰减和产生阻尼的原因;(3)从光压等效面积对称轴及光压冲量矩对称轴计算,钱德勒章动周期为435天左右。作者通过对地球东半球和西半球的北南部分相对赤道产生的光压矩对比分析,认为理论上地极的长期漂移是存在的。按现代全球陆地表面积沿经线的分布格局,长期极移的运动方向大致是沿西经90°向北美移动。作者引用统计资料,为太阳活动在地球上产生相对赤道的光压矩导致极移的理论提供了证据。     

核幔电磁耦合和钱德勒晃动

本文简要叙述了核幔电磁耦合和钱德勒晃动的研究成果和现状,计算了核幔电磁耦合力矩和晃动所需要的进动力矩,指出核幔电磁耦合起不到对钱德勒晃动的激发和阻尼作用,对进一步研究晃动这一尚未解决的问题无疑是有益处的。钱德勒晃动所需要的进动力矩为6.7×10~(20)N·m,而核幔电磁耦合所能提供给晃动的力矩比它要小4个量级。可见核幔电磁耦合起不到对钱德勒晃动的激发和阻尼作用,虽然它是地球转速变化的主要原因。     

随机激发过程对地极移动的作用

以随机微分方程组（1）作为地极移动（钱德勒摆动）的数学模型,求出了（1）的解。此解是二维的正态、平稳、马尔科夫随机过程,它具有遍历性.找到了它的转移概率密度和相关函数.通过对相关函数的研究,如果取ω=5.274,则钱德勘周期重合于强相关周期2π/ω;此外,还发现了另一个周期,即独立性周期π/ω.最后,研究了地极移动模型的最佳预测公式和预测误差.     

大西洋中北部双频微地动特征

本文对大西洋中北部两侧五个地震台站2015年记录到的地震数据进行处理,计算噪声功率谱密度和概率密度函数,并通过极化分析对双频微地动不同周期的主导源区方位角分布进行了分析.研究结果显示:大西洋中北部台站双频微地动发生显著分裂,各台站的峰值周期各不同,且来自相同方向和不同方向的双频微地动都有可能产生双频微地动分裂;大西洋中...     

地球自转学科中遗留若干主要难题的解析

近二百多年来的地球自转学科研究中,除岁差和章动的成因依据(万有)引力相互作用理论已经得到解决外,极移(包括长期极移)和日长(l.o.d)的变化问题一直还处在探讨和争论之中,尚遗留如下七个主要难题没有解决:1)极移是欧拉(Eular,1765)根据刚体自转的分析得出地球自转极相对地壳作周期为305天的摆动吗?2)极移周期的定量解释,钱德勒周期为什么不是单值的,约在425~440天之间变化?观测的极移轨迹运动周期为什么也不是单值的,而是在13.0~13.3个月之间变化?3)作为自由运动,钱德勒摆动最终将会逐渐衰减殆尽,为什么二百多年来的天文观测资料却未发现钱德勒振幅有任何渐自减弱的迹象,是什么因素在克服阻尼而维持这种运动呢?它的能量消耗到哪里去了?4)极移的成因机制是什么?5)极移与地震的关系?6)地球自转速度季节性变化的主要原因是什么?7)长期极移的成因及其运动方向?宋贯一(1991,2006,2008,2012)依据大量的宏观事实,发现和证明了自然界还存在有与(万有)引力相互作用相对应的(光压)斥力相互作用.本文依据(光压)斥力相互作用理论去解析上述七个难题,取得了立竿见影的效果.     

电离层GPS掩星观测反演技术

在电离层局部地区球对称假设下,推导了利用双频和单频无线电掩星观测数据,反演电离层电子密度剖面的两种方法. 双频反演的误差来自于载波相位的观测误差,单频反演误差则主要由伪距的观测精度决定. 由于载波相位测量精度比伪距测量精度高两个量级,因此双频反演的精度一般比单频反演的高些. 不过,两载波信号L1和L2之间的传播路径差异会给双频方法带来误差. 利用三维射线追踪的程序模拟的无线电掩星数据来评估这些方法,结果表明,反演出的电离层剖面与给定的模式电离层非常吻合,验证了两种方法的可靠性和准确性. 将这两种反演方法应用于处理实测的GPS/MET掩星观测数据,均能获取合理的电离层剖面信息. 且单频方法得到的反演剖面与双频方法相当一致, 这为利用LEO星载单频GPS接收机进行电离层掩星观测提供了理论基础.     

地球自转及其和地球物理现象的联系：：Ⅱ.地极运动

地球自转运动包括岁差和章动，极移和日长的变化，极移指自转轴相对地壳的运动。其主要激发原因是地球上物质分布的变化。因而，对极移的观测和研究必然为全球性的地球物理现象提供着信息。     

双频激电井地电位技术研究剩余油分布

双频激电井地电位法相对其它常规井地电位方法有独特优势和特点,利用该方法研究剩余油分布具备良好的理论和应用前景.但其理论机理、仪器方法及数据解释尚处于起步阶段.本文以大庆油田6-P2325井为倒,首次进行了双频激电井地电位探测,得到了地表的电位差分布图,把该图与前期结果进行对比表明应用该方法研究剩余油分布是可行的,可为剩余油分布研究提供信息数据,也可为深入研究大功率双频激电测井理论机理和仪器研制提供现场试验数据和依据.     

基于双频磁共振的未知拉莫尔频率地下水探测方法

在利用地面磁共振方法进行地下水探测时,要求发射频率与拉莫尔（Larmor）频率相同.由于地磁场的不均匀性和噪声干扰,实际测量时无法获得准确的Larmor频率,导致发生偏共振现象.如果假设磁共振或频率偏量未知时,反演得到的含水量和弛豫时间（T₂^*）将存在较大误差.为了解决未知Larmor频率情况下的准确探测问题,本文在频率环测量方案的基础上提出了双频磁共振探测方法,即只需知道Larmor频率的范围区间,通过区间外的两个频率进行偏共振激发,利用频率差值的一半作为频率偏量计算核函数,即可消除未知Larmor频率的影响.通过仿真实验,证明了在电阻率大于100 Ωm时,双频磁共振和偏共振的核函数偏差较小.对于双层含水层模型,双频磁共振和偏共振的信号偏差小于3 nV,因此得到双频磁共振信号可以用偏共振核函数进行反演.通过对假设磁共振、假设偏共振和双频磁共振反演结果的对比,可以得到在未知频率偏量和设定频率偏量改变时,双频磁共振均能得到准确的反演结果.但是,当环境噪声增加和电阻率降低时,反演结果的准确度降低.最后,通过长春市烧锅镇采集数据的反演结果与已知钻探资料进行对比,验证了双频磁共振探测方法的有效性和准确性.     

基于STM32和LabVIEW的双频激电信号采集系统设计

本文将LabVIEW与基于32位ARM单片机的数据采集电路结合,研究实现了一种高精度、多功能的双频激电信号采集系统.激电信号被采集系统接收后,经信号调理进入模数转换电路转换为数字信号,由USB接口送入基于LabVIEW软件平台的上位机中.上位机对该信号进行滤波选频、幅值测量、频谱分析、幅频率计算等处理,得到目标参数,同时还具有绘图、保存、查看等功能.本文就双频激电信号采集进行了阻容网络模拟实验,先用公式计算出理论视幅频率值,然后搭建电路进行实测.实验结果表明,该采集系统对双频激电信号采集的视幅频率测量误差小、精度高,具有良好的测量效果.     

地幔滞弹性对Chandler摆动的影响

基于简正模扰动理论和勒夫数扰动方法,采用Zschau 的地幔流变模型,在假设Chandler摆动的能量全部耗散于地幔滞弹性摩擦的条件下,导出Chandler 摆动Q(Q_w)的理论值.还考虑了滞弹地球的平衡极潮对摆动的影响,所得结果与绝大部分天文实测值非常一致.分析表明.平衡部分的影响大,地幔滞弹性很可能是Chandler 摆动最主要的能量耗散源,Q_w 的理论值约为71.还推算了吸收带模型参数α,研究了该模型的适用性,并讨论了Q_w 与地幔Q(Q_m)的关系.     

天文测时测纬的一种短时间异常与台站附近强震的对应关系

本文具体处理了自1966年以来,周围曾经发生过强震的北京,天津,东京（日本）,水泽（日本）及贝尔格莱德（南斯拉夫）等五个台站的测时测纬数据的残差,发现大震前的三、五个月内测时残差均出现一对符号相反的异常,而测纬残差则是一个孤立的单峰.这种震前的异常特征在无震的年份和无强震台站的资料（为了对比,又选了世界上观测稳定、质量较好的六架照相天顶筒,三架天顶仪和两架等高仪的资料）中极为罕见.对比关系较为密切,难于用偶然误差和其它影响来解释.各地测时与测纬残差异常特征的差异可能系地质构造不同所致.上述结论对进一步探讨地球自转的不均匀性的原因,提高时纬观测精度,揭示地下物质的运动形式及震源机制的本质等方面提供了新的线索和依据.     

大震前地震活动的图象识别

图象识别是近二十年来发展起来的一门学科,它已广泛应用于许多领域中。盖尔芬德(I.M.Gelfand)、普雷斯(F.Press)等人将它用于地震危险区的划分。本文将图象识别方法用于地震预测中,以识别强震发生的时间。 按一定标准将所研究的全部时间划分为危险时间段D和不危险时间段N。以问题表的形式提出大地震前中等地震活动的特性,然后分两步进行图象识别: 1.学习。对P个时间段m个问题的回答是mp的矩阵,回答以二进制(是或非)表示。通过学习,识别出一个、两个或三个问题组合的新特征,称之为D和N的性质。 2.投票。D和N性质数目的差是△,当△大于或等于某阈值时,则识别为危险段D,否则为N。 结果表明,大地震发生前的一定时期内,中等地震活动增至一定水平、相差半级的中等地震活动水平的比值较正常情况增高以及大震前中等地震活动随时间增强等性质的综合,表明未来时间段內可能发生大地震。 此外还作了控制试验,说明图象识别结果是稳定的。      

Polar motion influences in the gravity data recorded by superconducting gravimeters

Gravity data stored in the GGP database (GGP-ISDC) are used to study the small gravity variations caused by polar motion. In a first step the dominant tidal signal and the instrumental drift have to be eliminated from the gravity data. In most cases it is sufficient to model the instrumental drift by polynomials of low degree. The resulting non-tidal gravity variations are split up into their main constituents by fitting two sinusoidal waves with periods of 365.25 days (annual wobble) and 432 days (Chandler wobble). In a similar way the gravity effect of the observed polar motion (IERS-Data) is processed. The ratio between the correspondent amplitudes gives the amplitude factors δ of both wobbles.In a more sophisticated model an additional annual wave was included, destined to absorb disturbing influences with annual period (e.g. environmental influences of different origin). The amount of these influences and the success of their elimination are very different at the individual stations.Besides the comparison of the amplitude factors it also was tried to compare the gravity residuals itself. For that purpose the data series recorded at the different stations were transferred to a common reference point (0°E, 45°N). The graph of the stacked data series gives a first impression of the accordance of the data series recorded at the different stations. Since randomly distributed disturbing influences are reduced by the averaging the amplitude factors derived from the mean of the stacked data series are more reliable than the values derived from the data at the individual stations.In the end 12 data series were included in a common processing. Amplitude factors of 1.183 for the annual and 1.168 for the Chandler wobble result with mean errors less than ±0.010 (roughly estimated). Although corrections for environmental influences were not included directly, the additionally fitted annual wave reduced the scatter of the amplitude factors in the annual range considerably. In contrast to that the amplitude factor of the Chandler wobble remains nearly unaffected, confirming the assumption that the disturbing environmental influences do not extend into the period range of the Chandler wobble.     

Pollution history of the savannah river estuary and comparisons with Baltic Sea pollution history

The sediment record, as revealed in sediment cores, can be used to reconstruct the history of contaminant input into estuaries. The basic assumptions are that contaminant inputs equilibrate relatively rapidly with sediment inputs and that the sediment column represents a continuous sequence of sediment and associated contaminant accumulation. With radiochemical chronologies, it is possible to date sediments over a period corresponding to about five half-lives (100 years for ²¹⁰Pb). In our study we reconstruct the pollution history of the Savannah Estuary, which is a typical estuary in the South Atlantic Bight. A series of cores were taken in the estuary, followed by the analysis of the cores for a variety of organic and inorganic contaminants. Ages were assigned to different depth intervals by the use of two radiotracers, ²¹⁰Pb and ¹³⁷Cs. The major pesticides found were an isomer of DDT and dieldrin. The peak in their concentrations (1967) correlated with peak use of these pesticides before their use was banned. Between 1959 and 1962, there was more input of anthropogenic PAHs than before and after this period. The metals which showed significant changes in the cores include mercury, lead and chromium. Chromium reached a maximum during the late 1950s, followed by a decrease in the late 1960s. This chromium peak coincided with the initial operation of a titanium dioxide pigment plant in the Savannah Estuary. An interesting aspect of the study, which has been noted by many pollution history studies, was the decrease in the concentration of anthropogenic chemicals during the past two decades, suggesting that pollution controls have been effective, even while industrial and population growth was taking place.Similar studies have been carried out to reconstruct the historical record of contamination in the Baltic Sea. Concentrations of metals were found to increase after 1880 (industrial revolution in northern Europe). PCBs peaked in concentration in the late 1960s and the early 1970s, while DDT peaked in the 1960s. The Baltic experienced a major input of nutrients (N and P) after 1965 resulting from heavy use of fertilizers in this region.     

E) Organisations non Gouvernementales / Non Governmental Organizations

SUMMARY

The evaporation tank consists of a square pan with a flat base, 2 metres long and 0, 7 metre deep, set into the ground with the rim 0, 1 metre above, and connected to a well on which is installed a limnigraph. This limnigraph records continuously fluctuations of the free water surface.

The recordings show that a large amount of water can be evaporated during rainfall. This phenomenon is specific at every evaporation tank with a free water surface. It is only during the dry intervals that a strong correlation can be established between the evaporation measured in the tank and the potential evapotranspiration of the surrounding natural surfaces. In order to locate the dry intervals and to measure the evaporation only during these intervals, it is necessary to use an apparatus provided with a continuous recording mechanism     

利用小波分析重力的长期变化

运用小波滤波方法估算Chandler和周年项的潮汐因子.本文分析了四个台站(Brussels, Boulder, Membach以及Strasbourg)的观测记录,运用合成潮方法得到重力残差后,用Daubechies小波带通滤波器滤波残差,得到256～512 d时间尺度上的序列,根据标准差最小原则确定观测极潮周年和Chandler项的周期,然后利用最小二乘法估算它们的潮汐因子,同时给出未经模型改正的周年重力.由于高阶Daubechies小波构造的滤波器具有良好的频率响应,且能压制信号中的高阶异常成分,使滤波的信号更加光滑,因此计算结果具有更小的均方差,更加可靠.     

El Niño Impact on Polar Motion Prediction Errors

The polar motion prediction is computed as a least-squares extrapolation of the polar motion data. The least-squares model consists of a Chandler circle with constant or variable amplitude, annual and semiannual ellipses, and a bias. The model with constant amplitude of the Chandler oscillation is fit to the last three years of polar motion data and the model with variable amplitude of the Chandler oscillation is fit to the whole time series ranging from 1973.0 to 2001.1. The variable amplitude of the Chandler oscillation is modeled from the envelope of the Chandler oscillation filtered by the Fourier transform band pass filter from the long-term IERS EOPC01 polar motion series. The accuracy of the polar motion prediction depends mostly on the phase variation of the annual oscillation, which is treated as a constant in the least-squares adjustment. There were two significant changes of the annual oscillation phase of the order of 30° before the two El Niño events in 1982/83 and 1997/98.