The relationship between gravity and bathymetry in the Pacific Ocean

Summary. Surface-ship and satellite derived data have been compiled in new free-air gravity anomaly, bathymetry and geoid anomaly maps of the Pacific Ocean basin and its margin. The maps are based on smoothed values of the gravity anomaly, bathymetry and geoid interpolated on to a 90 × 90 km grid. Each smoothed value was obtained by Gaussian filtering measurements along individual ship and subsatellite tracks. The resulting maps resolve features in the gravity, bathymetry and geoid with wavelengths that range from a few hundred to a few thousand kilometres. The smoothed values of bathymetry and geoid anomaly have been corrected for age. The resulting maps show the Pacific ocean basin is associated with a number of ENE–WSW-trending geoid anomaly highs with amplitudes of about ± 5 m and wavelengths of about 3000 km. The most prominent of these highs correlate with the Magellan seamounts–Marshall Gilbert Islands–Magellan rise and the Hess rise–Hawaiian ridge regions. The correlation between geoid anomaly and bathymetry cannot be explained by models of static compensation, but is consistent with a model in which the geoid anomaly and bathymetry are supported by some form of dynamic compensation. We suggest that the dynamic compensation, which characterizes oceanic lithosphere older than 80 Myr, is the result of mantle convection on scales that are smaller than the lithospheric plates themselves.     

多期复测水准网和重力网的动态联合平差

在利用重力测量结果研究地壳垂直运动时，重力－高程因子的确定是一个需要研究的问题。本文提出利用多期复测水准网与重力网动态联合平差的方法，同时求解地壳垂直运动速率和重力－高程因子。利用此方法对北京地区１９８３－１９９１年的水准和重力复测结果进行了计算，结果表明：两类不同观测值的权比配置是恰当的，平差模型是正确的、重力－高程因子的分布符合一般规律。     

应用数值积分进行重力地形改正的F_(77)程序设计

本文用数值积分法,编制了F_(77)重力地形改正程序。它能用于各种重力工作的地形改正,并能满足重力地改的精度要求,通过人机对话的形式(菜单)可自选择改正条件,方便、灵活。     

德雷克海峡的扩张历史及其影响

本文利用首次南大洋考察期间获得的德雷克海峡地球物理场资料,解释海峡海底板块扩张历史以及海峡扩张对南极环境形成的影响.     

流动形变及重磁综合监测断层的研究

分析了目前利用流动形变、重力、地磁复测资料进行地震预测所存在的困难，探讨了综合利用三种手段追踪应力场及地下介质动态的途径，提出了断层综合监测布点的原则，并介绍了依此原则所建的京西试验场的基本情况。     

1988年澜沧─耿马地震与滇西实验场的重力变化

本文对澜沧─耿马大地震前后滇西实验场的重力场时空变化特征进行了初步分析，结果表明，地震之前，滇西实验场的重力变化有一个上升、下降的变化过程，地震发生在重力变化下降时段，震后迅速恢复。     

The impact of the new Earth gravity models on the measurement of the Lense–Thirring effect with a new satellite

In this paper we investigate the opportunities offered by the new Earth gravity models from the dedicated CHAMP and, especially, GRACE missions to the project of measuring the general relativistic Lense–Thirring effect with a new Earth’s artificial satellite. It turns out that it would be possible to abandon the stringent, and expensive, requirements on the orbital geometry of the originally prosed LARES mission (same semimajor axis a = 12,270 km of the existing LAGEOS and inclination i = 70°) by inserting the new spacecraft in a relatively low, and cheaper, orbit (a = 7500–8000 km, i  70°) and suitably combining its node Ω with those of LAGEOS and LAGEOS II in order to cancel out the first two even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential J₂, J₄ along with their temporal variations , . The total systematic error due to the mismodelling in the remaining even zonal harmonics would amount to 1% and would be insensitive to departures of the inclination from the originally proposed value of many degrees. No semisecular long-period perturbations would be introduced because the period of the node, which is also the period of the solar K₁ tidal perturbation, would amount to 10² days. Since the coefficient of the node of the new satellite would be smaller than 0.1 for such low altitudes, the impact of the non-gravitational perturbations of it on the proposed combination would be negligible. Then, a particular financial and technological effort for suitably building the satellite in order to minimize the non-conservative accelerations would be unnecessary.     

Nonlinear wave-wave interactions and wedge waves

A tetrad mechanism for exciting long waves, for example edge waves, is described based on nonlinear resonant wave-wave interactions. In this mechanism, resonant interactions pass energy to an edge wave,from the three participating gravity waves. The estimated action flux into the edge wave can be orders of magnitude greater than the transfer fluxes derived from other competing mechanisms, such as triad interactions. Moreover, the numerical results show that the actual transfer rates into the edge wave from the three participating gravity waves are two- to three- orders of magnitude greater than bottom friction.