共查询到19条相似文献，搜索用时 453 毫秒
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1978年5月使用了18台精度较高的重力仪在南京和北京分别建立了地震系统的重力检定场.本文结合以上成果和有关重力比较测定的资料, 从分析格值变化的各种因素及其产生的误差入手, 说明仪器格值标定的重要性和具体要求, 提出了选建地震系统重力检定场的方法技术和减小格值误差、提高测量精度的可能途径. 相似文献
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随着对重力测量精度要求的逐步提高,对各种误差的研究日渐深入,正确了解重力测量结果中各类误差的性质、来源、量级以及如何加以改正都是十分重要的问题。许多文献表明,当前各类误差中第一类半系统误差数值最大,它主要是由重力仪格值的误差引起的。而重力仪格值的误差在格值测定时就存在,这是由于重力仪自身的性能以及受外界因素的影响,使仪器格值发生波动和改变,从而增大了格值的误差。目前,我们还没有办法解决由重力仪自身性能所造成的仪器格值的改变,但受外界因素的影响,可通过一定的方法加以改善,现就温度变化对重力仪格值的影响作一简述。 相似文献
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介绍了中国科学院测量与地球物理研究所的LCR-ET20重力仪和中国地震局地震研究所的DZW-9重力仪在三峡水库首区的重力固体潮比对观测.获得了该地区高精度的重力固体潮潮汐参数,估算了DZW-9重力仪的格值,其值为（-756.06plusmn;0.05）times;10-8（mbull;s-2）/v. 分析了相应仪器的重力观测残差, 数值结果表明DZW-9重力仪的长期漂移具有线性特征, 观测精度与LCR-ET20重力仪在同一量级. 本文提供的相关结果可为该地区地表和空间大地测量观测提供有效的重力潮汐改正模型. 相似文献
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在重力观测中,影响观测精度的各项因素中,除温度的影响外,主要就是记录格值测定方法是否完善、标定是否准确。除了一般性的问题外,各台还有因其本身的环境条件而引起的具体问题。本文着重讨论郫县重力台使用 GS—15重力仪作静态观测中影响其记录格值的一些因素。郫县台历年重力测定记录格值资料示于图1.可以看出,1981年以前,记录格值变化 相似文献
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在地表重力观测过程中,CG-5重力仪的格值系数会随着时间推移而发生变化.选用河北测区内2015—2017年相对重力观测数据,基于重力差法对两台编号为C859、C873的CG-5相对重力仪进行格值系数的误差计算及修正,研究其变化特征,并对修正前后不同时间尺度的重力场变化进行对比分析.结果表明:两台CG-5相对重力仪的格值系数在3年内存在不同程度的变化,均呈现整体上升的趋势,累计变化量分别为0.028％,0.034％;采用修正后的格值系数可得到点值精度更高的平差结果;不同时间尺度上的重力场变化相比修正前也出现明显差异,2017年河北大城ML3.6级地震发生在格值系数修正后0.5 a期重力变化零值线附近,这些结果表明了对CG-5重力仪进行格值系数修正的正确性和必要性. 相似文献
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石英弹簧重力仪是我国地震系统目前进行野外重力重复观测的主要仪器。由于仪器格值及测量精度受环境温度影响较大,直接影响观测成果,迫切需要解决仪器恒温系统的配置。我所石英弹簧重力仪恒温装制研制组的同志根据 相似文献
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Accurate determination of calibration factor for tidal gravity observation of a GWR-superconducting gravimeter 总被引：4，自引：0，他引：4
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… 相似文献
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基于航空重力测量的基本数学模型,详细分析了航空重力测量的系统误差来源.大致可将系统误差分为三类,即停机坪重力基准值、比力初值的观测误差,格值、交叉耦合系数、摆杆尺度因子的标定误差和水平加速度改正的模型化误差等.然后,对每类系统误差的量级及其补偿方法进行了研究,指出水平加速度改正是引起系统误差的主要因素之一.大同、哈尔滨和渤海湾航空重力测量的实测数据分析均表明,在各项系统误差尤其是水平加速度改正得到有效补偿后,航空重力与地面(或船测)参考值的系统误差将小于1×10-5m·s-2. 相似文献
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V. A. Tulin 《Seismic Instruments》2008,44(1):40-49
The fundamentally new method of gravimetric observations is described, which is based on comparing the physically indistinguishable gravitational and inertial accelerations and has been developed by the Institute of Physics of the Earth n. a. O.Yu. Shmidt. Basics of theory of the gravimeter operation founded on this method are set forth. A peculiarity of the suggested method is the unlimited range of measurements and possibility of calibration for both downward and upward bias of the gravity force without involvement of additional equipment. It is shown that in observations using a mobile stand, the gravimeter based on this method is practically free of some systematic errors, inherent in instruments applied nowadays, which allows the gravimeter to be also used as a sea base station. 相似文献
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A. V. Sokolov A. A. Krasnov V. N. Koneshov V. V. Glazko 《Izvestiya Physics of the Solid Earth》2016,52(2):254-258
The experience with conducting a marine gravity survey onboard a surface vessel under complicated ice conditions at high latitude is described. In 2014, a high-precision marine gravity survey with two modifications of the Chekan-AM gravimeter was carried out in the North Pole region. The measurements were conducted during two months from aboard the Akademik Fedorov research vessel on a given grid with a total length of 10000 km of the routes. As a result, 70000 gravity points at Arctic latitudes including the region of the geographical North Pole itself are acquired. In this paper, we discuss the methodical aspects of conducting the survey and present the accuracy estimates of the gravity measurements. The comparison of the obtained results with the Earth’s gravity models demonstrates the absence of systematic errors and the higher spatial resolution of the measurements with the Chekan-AM gravimeters. 相似文献
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A network of gravity of control bases located at most of the airports and airfields in Nigeria has been established as a means of controlling future gravimetric studies in Nigeriaand of integrating existing gravity surveys into a unified whole for the purpose of producing gravity anomaly maps for the country. The network will also provide a means of checking and adjusting gravimeter calibration differences to a common standard.The LaCoste and Romberg gravimeters, models G446, G464 and G468, used for the observations were transported between the base stations by means of a six-seater fixed-wing aircraft. The scale adopted of the network was the same as that of gravimeter G464 to which the other two meters were referenced. The absolute gravity values observed ranged from 978184.882 ± 0.014 mGal at Nguru to 977844.379 ± 0.020 mGal at Jos, yielding a gravity range of 340.503 mGal. The accuracy of the individual absolute gravity value is better than 0.030 mGal using a datum value of 978120.933 mGal for site 103401 estlished at the Kano International Airport. The 34 observation sites are illustrated with sufficient detail to permit reoccupation within 0.50 m to 1.0 m. 相似文献
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The gravity method is one of the geophysical tools used for engineering and environmental investigations where the detection of cavities, karst phenomena, subsoil irregularities, or landfills is essential. In many cases, deep or small-scale heterogeneities generating low-amplitude anomalies have to be detected and the reliability of further interpretation requires highly accurate measurements, carefully corrected for any quantifiable disturbing effects. The purpose of this study is to investigate the factors likely to limit measurement quality and how to make improvements.Calibrations of a Scintrex gravimeter were made between French relative and absolute base stations, and the relative uncertainties on the calibration factors were estimated for these links. Ranging from 10−3, for calibration on an old gravity net, to 10−4, for a high amplitude absolute base line, this accuracy will be generally sufficient for microgravity surveys.Continuous gravity recordings of Scintrex gravimeters, installed at the same stable site, enabled the estimation of the stability and accuracy of the instruments and revealed that some of the time variations of g measurements, such as instrumental drift, tidal effects and seismic noise, are not entirely removed by standard processing procedures. The accuracy of corrected gravity measurements is mainly limited by inadequate corrections of tidal effects and by a poor estimation of ocean loading effects. In comparison with residual defaults in tidal corrections, instrumental and seismic noises are taken more properly into account by statistical data processing.In field operation, residual tidal effects are generally integrated into an experimental terrain drift estimated on the basis of frequent repeated measurements. A differential gravity approach, based on a fixed gravimeter reference whose recordings are used to correct measurements made with a mobile gravimeter, has also been investigated at a test site. Compared to standard processing, this method can help improve repeatability of gravity measurements.Microgravity surveys in the urban environment require effective and accurate consideration of the effects of infrastructures, nearby buildings and basements, as well as those of topography, in the vicinity of a gravity station. Correction procedures, applied at the same experimental site, where gravity points are located close to buildings, walls and basement slope, appear to have almost totally eliminated these disturbances. 相似文献
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摆杆尺度因子（K因子）是反映LaCoste&Romberg航空重力仪线性响应特性的最重要参数. 利用基于地面参考数据的外部标定法和基于交叉点不符值的内部标定法分别对其进行了标定，实测数据分析表明，K因子的内、外部标定结果非常一致，且利用新K因子计算的空中重力扰动，其精度较采用出厂值提高了02～04 mGal. 内部标定法具有较好的实际应用价值. 研究了K因子与滤波尺度的相关性，表明重力仪可能为一非线性响应系统，即K因子的大小与摆杆速度的变化有关. 相似文献
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Calibration shift seriously influences gravity values measured using Scintrex CG‐3M gravimeters. We calibrated three Scintrex CG‐3M gravimeters three times (1999, 2003 and 2006) over eight years, using a calibration line with a gravity difference of 1.38 Gal. The scale factor correction coefficients (calibration factors) obtained here range from 0.9998–1.0005. The calibration factors vary with time by 89 ppm, ?102 ppm and ?126 ppm between the 1999–2003 surveys. The calibration shifts of two of the three gravimeters decreased to about 20 ppm or less in the second interval, the other remained about the same (142 ppm). The results indicate that they shifted at rates on the order of 10 ppm/year even several years after manufacturing. The large shift in calibration factors indicates that they must be corrected using calibrations done before and after the measurements to perform microgravity measurements when gravity differences between a reference gravity site and survey sites are on the order of a hundred milligals (mGal) or more. The results also indicate that the calibration factors change gradually with time, so their interpolation provides a good practical approximation for a specific survey time. We applied the time‐dependent calibration factors to microgravity monitoring at the Iwo‐tou caldera, Japan, where the gravity difference between the base site on the island and the reference site on Honshu (the mainland of Japan) is about 870 mGal mainly due to the 11° latitude difference. Gravity surveys were conducted every two years from 1998–2006. The correction of scale factors estimated from the repeated calibration surveys leads to satisfactory measurements, in which the average of the absolute differences between two Scintrex CG‐3M instruments in five surveys is reduced from 207μGal to 19μGal; for three of those surveys, it is less than 10 μGal. This result demonstrates the importance of repeated calibration surveys. 相似文献