Core–mantle relative motion and coupling     

J. P. Vanyo 《Geophysical Journal International》2004,158(2):470-478

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RDAN97: An Analytical Development of Rigid Earth Nutation Series Using the Torque Approach     

F. Roosbeek  V. Dehant 《Celestial Mechanics and Dynamical Astronomy》1998,70(4):215-253

New series of rigid Earth nutations for the angular momemtum axis, the rotation axis and the figure axis, named RDAN97, are computed using the torque approach. Besides the classical J2 terms coming from the Moon and the Sun, we also consider several additional effects: terms coming from J3 and J4 in the case of the Moon, direct and indirect planetary effects, lunar inequality, J2 tilt, planetary‐tilt, effects of the precession and nutations on the nutations, secular variations of the amplitudes, effects due to the triaxiality of the Earth, new additional out‐of‐phase terms coming from second order effect and relativistic effects. Finally, we obtain rigid Earth nutation series of 1529 terms in longitude and 984 terms in obliquity with a truncation level of 0.1 μ (microarcsecond) and 8 significant digits. The value of the dynamical flattening used in this theory is HD=(C-A)/C=0.0032737674 computed from the initial value pa=50′.2877/yr for the precession rate. These new rigid Earth nutation series are then compared with the most recent models (Hartmann et al., 1998; Souchay and Kinoshita, 1996, 1997; Bretagnon et al., 1997, 1998. We also compute a benchmark series (RDNN97) from the numerical ephemerides DE403/LE403 (Standish et al., 1995) in order to test our model. The comparison between our model (RDAN97) and the benchmark series (RDNN97) shows a maximum difference, in the time domain, of 69 μas in longitude and 29 μas in obliquity. In the frequency domain, the maximum differences are 6 μas in longitude and 4 μ as in obliquity which is below the level of precision of the most recent observations (0.2 mas in time domain (temporal resolution of 1 day) and 0.02 mas in frequency domain). This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

地质计时的天文"钟摆"   总被引：18，自引：1，他引：17  

汪品先 《海洋地质与第四纪地质》2006,26(1):1-7

地球系统科学的发展,对于地质过程的时间度量提出了新要求。迄今为止,地球轨道参数的变化是地质尺度上惟一可以精确定量计算的周期现象,可以用作地质计时的标尺。40万年的偏心率长周期,是地质历史上最为稳定的轨道参数,至少在新生代以来通过低纬过程驱动着大洋碳储库的周期变化,是普遍出现而且容易辨认的轨道周期,可望作为地球历史的天文“钟摆”用于地质计时。  相似文献   

质子磁力仪电源系统     

田树德  马光  王树兴  魏连生  曾永忠  王莹楷 《山西地震》2007,(3):31-33

蓄电池过充电和过放电是导致其损坏的主要原因。质子磁力仪电源系统向用户提供了防止过充电和欠充电的铅蓄电池浮充电源、避免过放电的终止放电报警器和恒流输出式地磁分量补偿电源。介绍了该电源系统的性能和特点,各部分电路的工作原理、调试方法及使用注意事项。认为,使用该电源系统,不但可降低蓄电池的容量配制,延长其使用寿命,而且避免了充电和分量补偿电流调节的繁琐操作。  相似文献   

分量质子旋进磁力仪观测误差分析   总被引：1，自引：1，他引：0  

朱兆才 《地震地磁观测与研究》2000,21(2):48-53

分析了影响质子旋进磁力仪和分量质子旋进磁力仪观测质量的因素 ,给出了分量质子旋进磁力仪补偿线圈电流允许误差、补偿线圈定向 (特别是线圈磁南北方向 )应满足的关系式和定向允许误差。提出了分量质子旋进磁力仪的使用要点  相似文献   

非刚体地球的受迫章动奥波策项和倾斜模     

夏一飞  萧耐园 《天文学报》2000,41(3):300-305

讨论了非刚体地球受迫章动奥波策项与简正模表达式中倾斜模的关系。结果表明天球历书极章动中倾斜振项对应于角动量极的章动,在球历书极章动与角动量极的章动奥波策项之和。同时还给出了岁差速率与自转极的章动奥波策项间的数学关系。  相似文献   

Core precession: flow structures and energy     

J. P. Vanyo  & J. R. Dunn 《Geophysical Journal International》2000,142(2):409-425

Experiments using a precessing liquid-filled oblate spheroid with ellipticity ( a − b )/ a =1/400 extend and clarify earlier research. They yield flow data useful for estimating flows in the Earth's liquid core. Observed flows illustrate and confirm a nearly rigid liquid sphere with retrograde drift and lagging a cavity (mantle) axis in precession. The similarities of the observed lag angle with that computed for a rigid sphere, and earlier energy dissipation research both support the use of a rigid sphere analytical model to predict energy dissipation and first-order flow within the core–mantle boundary (CMB). Second-order boundary layer and interior cylindrical flow structures also are photographed and measured. Interior flows are never turbulent or unstable at near-Earth parameters, although complex and transient flow patterns are observed within the boundary layer. Other mechanisms proposed to explain net heat loss from the Earth and maintenance of the geodynamo typically require acceptance of some critical but unproven premise. Precession and CMB configuration are known with certainty and precision. Analytical difficulties have been the obstacle. Experiments illustrate the consequences of precession and ellipticity, provide criteria for validating analytical and numerical models, and may yield direct knowledge of the Earth's deep interior with careful scaling.  相似文献   

分量核旋仪偏置电流对磁偏角测量的影响分析   总被引：5，自引：2，他引：3  

冯志生  杨冬梅  夏忠  张秀霞  梅卫萍  嵇才键 《地震》2002,22(2):60-66

从理论上定量地分析了FHD-1型分量核旋仪的偏置电流对磁偏角观测值的影响,结果表明偏置电流的漂移对磁偏角观测值的影响随偏置电流的漂移量的增大而增大、也随磁偏角观测值的增大而增大,该结果对指导台站提高该仪器磁偏角观测值的精度有一定意义。  相似文献   

ITRS/J2000坐标转换误差及其对掩星反演的影响分析     

董启甲  程艳  周中华  许嵩  卿芸  汪文君 《大地测量与地球动力学》2021,41(5):530-534

分别对ITRS/J2000转换过程中的极移/潮汐章动、常数偏差矩阵等误差造成的影响进行分析,并分析季节变化、太阳活动、地磁活动等对坐标转换精度的影响。对2019年的IGS精密星历数据进行ITRS地固系转J2000惯性系坐标分析表明,潮汐章动造成的坐标转换误差为0.44 m,春季坐标转换误差(0.23 mm)是其他季节的约3倍;常数偏差矩阵对坐标转换误差可造成1.7 m的影响。对中性大气掩星反演的轨道转换加入误差改正项进行分析表明,潮汐章动和常数偏差矩阵对反演的温度产品分别造成0.09 K和0.19 K的误差影响。建议在进行GNSS无线电掩星反演中采用潮汐章动的高频改正,并且在ITRS/J2000转换过程中推荐将常数偏差矩阵进行旋转处理。  相似文献   

The Distinct Light Curve Shape of the Asteroid (469)     

Xiao-bin Wang  Xi-Liang Zhang  Sheng-hong Gu 《Earth, Moon, and Planets》2005,97(3-4):233-243

The observation light curves of the main belt asteroid (469) Argentina, obtained on March 9–11 2002 and August 10–11 2004, are presented in this paper. The complex light curve of the (469) suggests that it may be in NPA rotation. Using the Fourier analysis method, some prominent spectrum values are derived individually for two subset data. Among these period values, periods of 13.00 and 8.74 h are regarded as basic components. Other derived period values can be combined linearly with these two basic period values. If the (469) is in a free-force precession mode, the motion mode will be LAM (largest-axis mode) according the ratio of precession and rotation periods. And the minimum of I ₁/I ₃ (ratio of the largest and smallest principal momentum of inertial) is 3.05. Assuming an external torque releasing by a satellite forces the (469) to precess, the mass of satellite roughly is the same order as the primary’s on condition that the precession and rotation periods are two basic values. At present, we cannot draw an unambiguous conclusion on (469)’s motion for sparse data, So the further observations are necessary for understanding the (469)’s tumbling motion farther.  相似文献