Estimation of the pole tide gravimetric factor at the chandler period through wavelet filtering

Wavelet analysis for filtering is used to improve estimation of gravity variations induced by Chandler wobble. This method eliminate noise in superconducting gravimeter (SG) records with bandpass filters derived from Daubechies wavelet. The SG records at four European stations (Brussels, Membach, Strasbourg and Vienna) are analysed in this study. First, the earth tidal constituents are removed from the observed data by using synthetic tides, then the gravity residuals are filtered into a narrow period band of 256–512 d by a wavelet bandpass filter. These data are submitted to three regression analysis methods for estimating the gravimetric factor of the Chandler wobble. After processing by wavelet filtering, SG records can provide amplitude factors δ and phase lags κ of the Chandler wobble with much smaller mean square deviation (MSD) than these provided by former studies. It is mainly because the wavelet method can effectively eliminate instrumental drift and provide smoothed data series for the regression analysis.     

Airborne LaCoste &; Romberg gravimetry: a space domain approach

This paper introduces a new approach to reduce the airborne gravity data acquired by a LaCoste &; Romberg (L&;R) air/sea gravimeter, or other similar gravimeters. The acceleration exerted on the gravimeter is the sum of gravity and the vertical and Eötvös accelerations of the aircraft. The L&;R gravimeter outputs are: (1) the beam position, (2) the spring tension and (3) the cross coupling. Vertical and Eötvös accelerations are computed from GPS-derived aircraft positions. However, the vertical perturbing acceleration sensed by the gravimeter is not the same as the one sensed by the aircraft (via GPS). A determination of the aircraft-to-sensor transfer function is necessary. The second-order differential equation of the motion of the gravimeter’s beam mixes all the input and output parameters of the gravimeter. Conventionally, low-pass filtering in the frequency domain is used to extract the gravity signal, the filter being applied to each flight-line individually. By transforming the differential equation into an integral equation and by introducing related covariance matrices, we develop a new filtering method based on a least-squares approach that is able to take into account, in one stage, the data corresponding to all flight-lines. The a posteriori covariance matrix of the estimated gravity signal is an internal criterion of the precision of the method. As an example, we estimate the gravity values along the flight-lines from an airborne gravity survey over the Alps and introduce an a priori covariance matrix of the gravity disturbances from a global geopotential model. This matrix is used to regularize the ill-posed Fredholm integral equation introduced in this paper.     

国际GGP计划和武汉超导重力仪观测

介绍了近年来应用部分超导重力仪观测研究地球动力学研究方面的成果 ,包括精密测定地球潮汐常数 ,研究大气和海洋潮汐信号 ,确定地球自由核章动参数和检测地球自由振荡等内容。     

Accurate determination of calibration factor for tidal gravity observation of a GWR-superconducting gravimeter

Introduction The superconducting gravimeters (SGs) are widely used to observe the change in temporal and spatial gravity field by many countries along the world, considering their characteristics as of the high-precision, good continuity and stability. By using the temporal variation of the tidal grav-ity obtained from the global network of SGs, the Global Geophysics Project (GGP) aims at some hot problems in geophysics and geodynamics (SUN, HSU, 1997). The original observations of the c…     

论分段格值计算重力单程观测法公式

国产石英弹簧大测程重力仪分段标定的格值相对变化＞1／1400时，文中总结分段格值计算单程观测（混合零点位移改正、固体潮改正、静掉格改正）的公式。     

中国新的重力基本网

我国旧重力基本网建于1957年,约含有13.5mGal的基准误差和0.2‰的尺度误差,现已被新的国家重力基本网1985系统（新网）取代。新网由57个点组成,其中有6个绝对重力点。整体平差后点重力值平均中误差为±7.8μGal。经外部检核,实际精度达20μGal,经过实际使用,证明估计精度正确。本文讨论了国际重力基准、LCR-G重力仪特性、高精度重力网平差及我国旧网的实际精度及其转换等问题。     

用潮汐重力仪探测引力吸收效应的可能性

用潮汐重力仪探测引力吸收效应的工作始于本世纪150年代,但至今仍然没有得到证实。一个可能的原因是引力吸收效应比理论预言值小得多。究竟情况如何,还有待更精密的实验。本文首先推导出了引力吸收效应方程及引力定律,结果与Harrison(1963)给出的一致;然后就如下几种情况对用潮汐重力仪探测引力吸收效应的可能性进行了探讨: 1) 利用地球作屏蔽;2) 利用月球作屏蔽;3).利用太阳作屏蔽;4) 利用人造地球卫星的摄动。     

正电子CT（PET）与21世纪生命科学

２１世纪的生命科学有两大前沿领域：分子生物学和神经生物学，前者研究人体生命过程的基因调控机制，而神经生物学则以探索人脑思维的奥秘为主要目标，正电子层析成像（ＰＥＴ）是研究人体内部分子相互作用动力学的和最有力的方法，并可研究脑的功能定位，ＰＥＴ的化学精度已达到ｐ ｍｏｌ水平，其空间分辨率为毫米数量级。ＰＥＴ将对２１世纪生命科学的巨大进展，起决定性的推动作用。     

CHZ-Ⅱ海空重力仪格值标定

详细介绍了倾斜法标定格值,并利用自主研发的CHZ-Ⅱ海空重力仪进行格值标定实验,得到格值最终的加权平均值。