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利用武汉台站GWR_C032超导重力仪观测资料,在对原始数据进行有效预处理的基础上作调和分析,获得反映地球内部介质特征的重力潮汐参数.基于卫星测高技术和有限元方法同时考虑验潮站数据作约束条件获得的多个全球海潮模型,利用负荷理论和数值褶积积分技术计算了重力负荷,对周日和半日频段内的重力潮汐参数实施负荷改正,提出了“负荷改正有效性”概念,研究了全球海潮模型适应性.数值结果说明,海潮改正的有效性高达91%（O1,NAO99）和92%（M2,ORI96）.基于11个海潮模型对主波（O1,K1,M2和S2）的负荷改正说明平均有效性为（86%,70%,73%和84%）,振幅因子与理论模型间的差异分别从（212%,155%,116%和080%）降到（031%,039%,034%和008%）,同时还说明利用NAO99和ORI96全球海潮模型能获得比其他模型更佳的负荷改正效果.文章还利用国际地球动力学计划网络其他7个台站的超导重力仪观测研究了全球海潮模型的适定性问题,结果说明不同模型中不同潮波具有明显的区域特点,早期构制的SCW80全球海潮模型仍可作为大地测量研究中的重要参考模型. 相似文献
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采用武汉台超导重力仪(SG C032)14年多的长期连续观测资料,研究了固体地球对二阶和三阶引潮力的响应特征,精密测定了重力潮汐参数,系统研究了最新的固体潮模型和海潮模型在中国大陆的有效性.采用最新的8个全球海潮模型计算了海潮负荷效应,从武汉台SG C032的观测中成功分离出63个2阶潮汐波群和15个3阶潮汐波群信号,3阶潮波涵盖了周日、半日和1/3日三个频段.重力潮汐观测的精度非常高,标准偏差达到1.116 nm·s-2,系统反映了非流体静力平衡、非弹性地球对2阶和3阶引潮力的响应特征.结果表明,现有的武汉国际重力潮汐基准在半日频段非常精确,但在周日频段存在比较明显的偏差,需要进一步精化.对于中国大陆的大地测量观测,固体潮可以采用Dehant等考虑地球内部介质非弹性和非流体静力平衡建立的固体潮理论模型或Xu 等基于全球SG观测建立的重力潮汐全球实验模型作为参考和改正模型,海潮负荷效应应该采用Nao99作为改正模型. 相似文献
3.
本文讨论了海潮对卫星重力测量的影响问题. 首先介绍了海潮对卫星重力测量影响的基本理论;采用FES02和TPXO6海潮模型计算了海潮负荷对卫星重力结果前60阶的影响;并用两个模型之间的差异作为海潮模型精度的估计量,据此计算了海潮模型误差对卫星重力结果的影响. 与GRACE恢复的重力场精度的比较说明：海潮对重力场40阶以下的影响都超过了目前重力场恢复精度;尽管由于卫星测高技术的发展,海潮模型的精度有了很大的提高,但目前的全球海潮模型用于GRACE重力场恢复的前12阶的改正还是不够精确. 另外,我们也利用中国东海和南海潮汐资料以及FES02海潮模型讨论了中国近海潮汐效应对GRACE观测的影响. 结果说明该影响与海潮模型的误差相当. 这反映了当前海潮模型的不确定度,因此通过结合全球验潮站资料有望提高海潮对卫星重力测量的改正精度. 相似文献
4.
本文根据计算地倾斜负荷潮的积分Green函数方法,计算了全球Schwiderski海潮模型K_1、O_1分波在中国大陆产生的地倾斜负荷潮,绘制了K_1、O_1分波负荷潮椭圆及其长轴迹线,沿长轴方向分量的等潮时线,长、短半轴等值线诸地倾斜负荷潮参量在中国大陆境内的分布图,给出了它们的空间分布图象,为国内的地倾斜固体潮研究提供了重要的参考资料. 相似文献
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Gravity tide records from El Hierro, Tenerife and Lanzarote Islands (Canarian Archipelago) have been analyzed and compared to the theoretical body tide model (DDW) of Dehant el al. (1999). The use of more stringent criterion of tidal analysis using VAV program allowed us to reduce the error bars by a factor of two of the gravimetric factors at Tenerife and Lanzarote compared with previous published values. Also, the calibration values have been revisited at those sites. Precise ocean tide loading (OTL) corrections based on up-to-date global ocean models and improved regional ocean model have been obtained for the main tidal harmonics O1, K1, M2, S2. We also point out the importance of using the most accurate coastline definition for OTL calculations in the Canaries. The remaining observational errors depend on the accuracy of the calibration of the gravimeters and/or on the length of the observed data series. Finally, the comparison of the tidal observations with the theoretical body tide models has been done with an accuracy level of 0.1% at El Hierro, 0.4% at Tenerife and 0.5% at Lanzarote. 相似文献
8.
Determination of vertical displacements over the coastal area of Korea due to the ocean tide loading using GPS observations 总被引：2，自引：0，他引：2
This paper describes the GPS applicability for detecting the vertical displacements of ground stations caused by ocean tide loading effects. An experiment was carried out using 12 permanent GPS stations located in the coastal area of Korea using data in the period 1 July until 26 August 2003. The relative height differences were calculated from hourly DGPS data processing based on the carrier-phase observation. The power spectra of the M2 and N2 constituents of ocean tide loading were derived using the CLEAN algorithm. The differential vertical displacements generated by the ocean tide loading effect are typically 3–25 mm in coastal area of the Korea. We compared the results from GPS with those of the ocean tide models, NAO.99Jb regional model and GOT00.2, FES99 global models. The M2 (N2) amplitude differences of vertical displacements between GPS and GOT00.2 is 1.22 ± 3.61 mm (1.01 ± 1.48 mm), and that of the M2 (N2) amplitude difference between GPS and FES99 is 0.04 ± 4.64 mm (0.64 ± 1.75 mm), whereas the M2 (N2) amplitude difference between GPS and NAO.99Jb are 0.05 ± 1.03 mm (0.86 ± 1.18 mm). The highest vertical displacements at the PALM station are found for 24.5 ± 0.7 mm from GPS observation, and 22.9 mm from the regional model NAO.99Jb and 13.17 and 10.00 mm from the global models GOT00.2 and FES99, respectively. These values show that the vertical displacements derived from GPS are in good agreement with those of the regional model NAO.99Jb around Korea, more than with the global models. This result indicated that GPS is an effective tool to measure the vertical displacement caused by the ocean tide loading effect in the coastal area, and we need to use the NAO.99Jb ocean tide model rather than the global ocean tide models in and around the Korean peninsula for position determination with permanent GPS installations. This work demonstrates that vertical displacement caused by the M2 and N2 constituents of ocean tide loading can be measured by carrier-phase DGPS. 相似文献
9.
详细介绍了海潮负荷影响的计算理论,基于PREM地球模型计算了地球内部的负荷勒夫数及负荷格林函数;并以上海台和武汉台为例,计算了海潮负荷对不同深度处的应力和应变潮汐的影响. 结果表明:深度是影响海潮负荷应力的一个重要因素,在靠近计算点的区域,应力负荷的影响随深度增大而减小;而对于远离计算点的区域,应力负荷的影响却随深度增大而增大;另外,深度会影响某些应力和应变潮汐分量时间变化的相位. 在沿海地区,海潮负荷对应力和应变的影响超过了应力和应变固体潮的影响,因此该影响在应力和应变测量中必须要加以考虑. 相似文献
10.
The inter-annual variability of the sea surface temperature (SST) was analyzed along the western Iberian Peninsula in the region ranging from 9.5 °W to 21.5 °W and from 37.5 °N to 42.5 °N with a spatial resolution of 1°×1° from 1900 to 2008. Both coastal and oceanic SST showed an overall increase with warming and cooling cycles similar to those observed in the North Atlantic region and in previous regional studies. In addition, the evolution of coastal and ocean water has been observed to be different. In general, ocean water is more affected by the different warming–cooling cycles than coastal water. In spite of coast and ocean are highly influenced by global changes affecting the whole North Atlantic region, near shore SST has been observed to be correlated with local wind regime, which is itself a manifestation of the Eastern Atlantic (EA) teleconnection pattern. 相似文献
11.
海潮误差是GRACE时变重力场反演中重要的误差源,目前发布的海潮模型中主要包含振幅较大的主潮波分量模型,在时变重力场反演中次潮波的影响也是不可忽略的,因此,GRACE时变重力场反演中的海潮误差主要包括受限于海潮模型误差和次潮波影响.本文利用轨道模拟方法检测了短周期潮波的混频周期以及次潮波对ΔC20,ΔC30的时序特征,并进一步通过轨道模拟结果分析了海潮误差对时变重力场反演的影响,然后通过实测数据解算分析了海潮误差对当前GRACE时变重力场解算的影响,研究发现:(1)利用轨道模拟能够有效地检测短周期潮波的混频周期;(2)时变重力场解算过程中,次潮波的影响大于海潮模型误差的影响;(3)海潮模型误差以及次潮波影响是当前GRACE没有达到基准精度的重要因素之一. 相似文献
12.
《Journal of Geodynamics》2009,47(3-5):78-89
We analyzed gravity data obtained in Juneau and global positioning system (GPS) data obtained from three PBO sites in southeastern Alaska (SE-AK), which are part of a US research facility called ‘EarthScope’, and we compared the obtained tidal amplitudes and phases with those estimated from the predicted tides including both effects of the body tide and ocean tide. Global tide models predict the ocean tides in this region of complex coastline and bathymetry. To improve the accuracy of prediction, we developed a regional ocean tide model in SE-AK.Our comparison results suggest: (1) by taking into account the ocean tide effect, the amplitude differences between the observation and the predicted body tide is remarkably reduced for both the gravity and displacement (e.g. for the M2 constituent, 8.5–0.3 μGal, and 2.4–0.1 cm at the AB50 GPS site in Juneau in terms of the vector sum of three components of the north–south, east–west and up–down), even though the ocean tide loading is large in SE-AK. (2) We have confirmed the precise point positioning (PPP) method, which was used to extract the tidal signals from the original GPS time series, works well to recover the tidal signals. Although the GPS analysis results still contain noise due to the atmosphere and multipath, we may conclude that the GPS observation surely detects the tidal signals with the sub-centimeter accuracy or better for some of the tidal constituents. (3) In order to increase the accuracy of the tidal prediction in SE-AK, it is indispensable to improve the regional ocean tide model developed in this study, especially for the phase. 相似文献
13.
T. Sato S. Miura Y. Ohta H. Fujimoto W. Sun C.F. Larsen M. Heavner A.M. Kaufman J.T. Freymueller 《Journal of Geodynamics》2008,46(3-5):78
We analyzed gravity data obtained in Juneau and global positioning system (GPS) data obtained from three PBO sites in southeastern Alaska (SE-AK), which are part of a US research facility called ‘EarthScope’, and we compared the obtained tidal amplitudes and phases with those estimated from the predicted tides including both effects of the body tide and ocean tide. Global tide models predict the ocean tides in this region of complex coastline and bathymetry. To improve the accuracy of prediction, we developed a regional ocean tide model in SE-AK.Our comparison results suggest: (1) by taking into account the ocean tide effect, the amplitude differences between the observation and the predicted body tide is remarkably reduced for both the gravity and displacement (e.g. for the M2 constituent, 8.5–0.3 μGal, and 2.4–0.1 cm at the AB50 GPS site in Juneau in terms of the vector sum of three components of the north–south, east–west and up–down), even though the ocean tide loading is large in SE-AK. (2) We have confirmed the precise point positioning (PPP) method, which was used to extract the tidal signals from the original GPS time series, works well to recover the tidal signals. Although the GPS analysis results still contain noise due to the atmosphere and multipath, we may conclude that the GPS observation surely detects the tidal signals with the sub-centimeter accuracy or better for some of the tidal constituents. (3) In order to increase the accuracy of the tidal prediction in SE-AK, it is indispensable to improve the regional ocean tide model developed in this study, especially for the phase. 相似文献
14.
Accuracy assessment of ocean tide loading computations for precise geodetic observations 总被引：1，自引：0，他引：1
The increasing resolution of ground based gravity measurements (e.g. by superconducting gravimeters) as well as satellite based gravity field studies allows to study very small signals, globally as well as local. On the other hand, this requires the correction of such signals to uncover others. To study the Earth’s deep interior and the on-going dynamic processes requires the correction of disturbing signals, and one of these signals is related to ocean tidal loading. Although new ocean tide models are being derived from current satellite missions, there are still uncertainties.In this paper we present an intercomparison ocean tide models to test their fit to world-wide observations. Therefore, three TOPEX/POSEIDON (T/P) satellite derived models (CSR3.0, FES95.2 and TPXO.2) beside the classical SCHW80 model were selected for an accuracy assessment study. The selected models have been subjected to an intercomparison test, tide gauge validation test and comparison to 59 tidal gravity stations.The intercomparison test shows a good agreement between the T/P-based models for the open ocean and remarkable disagreement between the selected models in the coastal regions indicating that such models are still problematic in these regions. The tide gauge validation shows that the T/P derived models fit tide gauges better than SCHW80, with a better fit for the semidiurnal constituents than for the diurnal constituents. Comparing the gravimetric ocean-tide loading computed from the selected models with the residuals from a set of 59 tidal gravity stations shows that there is an improvement of the T/P derived models with respect to the Schwiderski model, especially in M2. However, this improvement is not as significant as the result of the comparison with the pelagic data. The procedure developed for the comparison of T/P derived models with SCHW80 is presented. The results provide not only information and improvement with regard to SCHW80, but also information about the properties of the new models. It is intended to continue this work applying the very recent models to see how they perform compared to this study.With this study we provide boundary conditions for the improvement of new ocean-tide models in order to benefit from the gravity measurements now possible regarding the evaluation of Earth structures and dynamic processes. 相似文献
15.
《Journal of Geodynamics》2007,43(4-5):159-174
The increasing resolution of ground based gravity measurements (e.g. by superconducting gravimeters) as well as satellite based gravity field studies allows to study very small signals, globally as well as local. On the other hand, this requires the correction of such signals to uncover others. To study the Earth’s deep interior and the on-going dynamic processes requires the correction of disturbing signals, and one of these signals is related to ocean tidal loading. Although new ocean tide models are being derived from current satellite missions, there are still uncertainties.In this paper we present an intercomparison ocean tide models to test their fit to world-wide observations. Therefore, three TOPEX/POSEIDON (T/P) satellite derived models (CSR3.0, FES95.2 and TPXO.2) beside the classical SCHW80 model were selected for an accuracy assessment study. The selected models have been subjected to an intercomparison test, tide gauge validation test and comparison to 59 tidal gravity stations.The intercomparison test shows a good agreement between the T/P-based models for the open ocean and remarkable disagreement between the selected models in the coastal regions indicating that such models are still problematic in these regions. The tide gauge validation shows that the T/P derived models fit tide gauges better than SCHW80, with a better fit for the semidiurnal constituents than for the diurnal constituents. Comparing the gravimetric ocean-tide loading computed from the selected models with the residuals from a set of 59 tidal gravity stations shows that there is an improvement of the T/P derived models with respect to the Schwiderski model, especially in M2. However, this improvement is not as significant as the result of the comparison with the pelagic data. The procedure developed for the comparison of T/P derived models with SCHW80 is presented. The results provide not only information and improvement with regard to SCHW80, but also information about the properties of the new models. It is intended to continue this work applying the very recent models to see how they perform compared to this study.With this study we provide boundary conditions for the improvement of new ocean-tide models in order to benefit from the gravity measurements now possible regarding the evaluation of Earth structures and dynamic processes. 相似文献
16.
利用中国计量科学研究院北京昌平基地iGrav-012超导重力仪最新观测资料,对其作仔细地预处理,根据调和分析方法精密测定了重力潮汐参数,基于负荷理论与卷积积分技术获得了包含HAM11a,DTU10,EOT11a在内的14个全球海潮模型的重力海潮负荷效应,利用近周日频段内潮波振幅因子的共振效应求解了自由核章动(FCN)的本征参数.调和分析结果表明,重力潮汐的观测精度非常高,标准差达到1.184nm·s-2.基于加汉宁窗的快速傅里叶变换方法获得地震频段的地震噪声等级(SNM)为0.206,说明该台站是低背景噪声的.周日主波O1和K1经海潮模型作负荷效应改正的平均有效性分别为83%和85%;使用13个高精度海潮模型进行迭积计算获得的FCN本征周期为430.0(427.8,432.3)恒星日,品质因子Q值为-5137. 相似文献
17.
热带气旋能在短期内造成海水和大气质量的重新分布,使得近海地表受力发生变化,进而产生非潮汐负荷形变,对现今高精度大地测量的影响已不容忽视.为了保证空间大地测量结果的精度和稳定性,热带气旋引起的地表形变必须进行有效的估计.因此本文联合NOS、GLOSS验潮站数据与海潮模型,通过获取非潮汐残余量分析了热带气旋“MATTHEW”引起的风暴潮.利用ECCO海洋环流模型、ERAin大气再分析模型、HUGO-m海洋动力学模型,分别估计了“MATTHEW”引起非潮汐海洋负荷、非潮汐大气负荷、动力学响应下非潮汐海洋负荷对地表位移的影响,结果表明热带气旋影响下的广大区域地表都不同程度受到非潮汐负荷的作用,最大位移分别达到-9.13 mm、3.31 mm、-6.11 mm,并且加入动力学响应的非潮汐海洋负荷要普遍大于IB(Inverted Barometer)响应下的结果.在对比不同位置站点所受负荷差异时,发现“大陆站”非潮汐海洋负荷形变普遍大于“岛屿站”,而“岛屿站”更易受非潮汐大气负荷的影响. 相似文献
18.
M. Moens 《Physics of the Earth and Planetary Interiors》1976,13(3):197-211
The three components of the indirect oceanic effect are calculated for the M 2, K 1 and O 1 waves and compared with the observed earth tide. The vertical component of the near Arctic oceanic load explains fairly well the large 45° observed phase lag of M 2. The results for the horizontal components are satisfactory; the discrepancies between different tiltmeters are not due to the oceanic perturbations (unless some local or cavity effects are supposed). 相似文献
19.
《Journal of Geodynamics》2010,49(3-5):354-359
In order to achieve a consistent combination of terrestrial and satellite-derived (GRACE) gravity field variations reductions of systematic perturbations must be applied to both data sets. At the same time evidence needs to be provided that these reductions are both necessary and sufficient. Based on the OMCT and the ECCO model the gravity effect of non-tidal oceanic mass shifts is computed for various sites equipped with a superconducting gravimeter (SG) and esp. the long-periodic contributions are studied. With these oceanic models the dynamic ocean response to atmospheric pressure loading is automatically computed, and thus goes beyond the more simplistic concepts of an inverted barometer, or alternately a rigid ocean, which is a clear advantage.The findings so far are ambiguous: for instance the systematic seasonal change of about 10 nm/s2 in gravity for mid-European stations is presently not found in the observed gravity variations. Generally, the order of magnitude of the total effect of 22–27 nm/s2 is surprisingly large for inland stations. In some data sections the reduction leads to the removal of some of the larger residuals. The results obtained for the South-African station Sutherland differ. Here the modelled seasonal variation caused by the non-tidal oceanic mass redistribution and gravity residuals generally correlate, and thus by the reduction an improvement of the signal-to-noise ratio in the gravity observations is achieved.An explanation for the different results might be found in the global hydrological models. Such a model is needed in order to remove the effect of large-scale variations in continental water storage in the gravity observations. This reduction plays a greater role for European stations than for the South African site. A critical impact of the land-sea-mask used in the oceanic models and the subsequent insufficient resolution of the North and Baltic Sea on the computations at the mid-European sites could not be confirmed.From a comparison between the OMCT and the ECCO model substantial discrepancies in some regions of the earth emerge, while both predict variations at inland stations in Europe, South Africa, and Asia of similar magnitude. We currently hesitate to recommend including this reduction in the routine processing of SG data because the seasonal order of magnitude for inland stations is unexpectedly large and partly significant deviations between the modelled oceanic effects exist. If the order of magnitude proves to be correct universally, this reduction has to be applied. 相似文献
20.
P. Melchior M. Moens B. Ducarme M. Van Ruymbeke 《Physics of the Earth and Planetary Interiors》1981,25(1):71-106
A knowledge of the vertical component of the oceanic tidal load to a precision of at least one microgal is essential for the geophysical exploitation of the high-precision absolute and differential gravity measurements which are being made at ground level and in deep boreholes. On the other hand the ocean load and attraction signal contained in Earth tide gravity measurements can be extracted with a precision which is sufficient to characterize the behaviour of the oceanic tides in different basins and this provides a check of the validity of the presently proposed cotidal maps. The tidal gravity profiles made since 1971 from Europe to Polynesia, through East Africa, Asia and Australia, with correctly intercalibrated gravimeters, comprise information from 91 tidal gravity stations which is used in this paper with this goal in mind.A discussion of all possible sources of error is presented which shows that at the level of 0.5 μgal the observed effects cannot be ascribed to computational or instrumental errors. Cotidal maps which generate computed loads in agreement with the Earth tide gravity measurements over a sufficiently broad area can be used with confidence as a working standard to apply tidal corrections to high-precision measurements made by using new techniques in geodesy, geophysics and geodynamics, satellite altimetry, very long baseline interferometry, Moon and satellite laser ranging and absolute gravity. The recent cotidal maps calculated by Schwiderski for satellite altimetry reductions agree very well with land-based gravimeter observations of the diurnal components of the tides (O1, K1 and P1 waves) but his semi-diurnal component maps (M2, S2 and N2 waves) strangely appear less satisfactory in some large areas. The maps of Hendershott and Parke give good results in several large areas but not everywhere. More detailed investigations are needed not only for several coastal stations but mainly in the Himalayas. 相似文献