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1.
利用FG5绝对重力仪进行南极长城站绝对重力测定 总被引:1,自引:0,他引:1
在南极地区进行重力测量是建立高程基准的基础,2005年,在南极长城站进行了绝对重力测量,观测仪器采用FG5绝对重力仪,经固体潮改正、海潮改正、极移改正及气压改正等,精度达±3×10-8m s-2,并同时利用2台LCR相对重力仪进行了重力垂直梯度测量和水平梯度测量。长城站绝对重力测量的实施,对于新一代卫星重力计划如CHAMP、GRACE和GOCE的地面校准及建立南极地区的高精度、高分辨率的大地水准面模型提供了基础数据。 相似文献
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Takahito Kazama Hideaki Hayakawa Toshihiro Higashi Shingo Ohsono Shunsuke Iwanami Tomoko Hanyu Harumi Ohta Koichiro Doi Yuichi Aoyama Yoichi Fukuda Jun Nishijima Kazuo Shibuya 《Polar Science》2013,7(3-4):260-277
Absolute gravity values were measured with a portable absolute gravimeter A10 in East Antarctica, for the first time by the Japanese Antarctic Research Expedition. This study aims to investigate regional spatiotemporal variations of ice mass distributions and associated crustal deformations around Syowa Station by means of repeated absolute gravity measurements, and we obtained the first absolute gravity value in Southern Langhovde on the Antarctic Continent. The average absolute gravity value at the newly installed benchmark AGS01 in Langhovde (obtained on 3 February 2012) was 982535584.2 ± 0.7 μgal (1 [μgal] = 1 × 10?8 [m/s2]), which was in agreement with the gravity values obtained by the past relative gravity measurements within 1 mgal. In addition, the average absolute gravity value obtained at AGSaux in Syowa Station was consistent with both previous absolute gravity values and those obtained by simultaneous measurements using an FG5 gravimeter, owing to adequate data corrections associated with tidal effects and time variations in atomic clock frequencies. In order to detect the gravity changes associated with the ice mass changes and other tectonic phenomena, we plan to conduct absolute gravity measurements at AGS01 again and at other campaign sites around Syowa Station as well in the near future, with careful attention paid to the impacts of severe environmental conditions in Antarctica on gravity data collection. 相似文献
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中国南极中山站位于南极拉斯曼丘陵地区(λ=76°22′E,φ=69°22′S),1991年3月至1993年2月,用LacosteET型重力仪,在这个地区进行了为期近两年的观测,取得了600多天的有效资料,经调和分析和流变模型、海潮负荷改正后得到:δo1=1.2253±0.0031,Δφo1=0.73°±0.14°;δm2=1.0785±0.0045,Δφm2=-3.55°±0.29°从资料分析的精度来看,观测资料是比较好的;但由于海潮负荷改正缺少附近海域的资料,会对最终结果造成较大的影响 相似文献
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《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):79-84
Absolute gravity observations yield insight into geophysical phenomena such as postglacial rebound, change in the Earth's hydrological cycle, sea level change, and changes in the Earth's cryosphere. In the article, the first gravity values at 16 Norwegian stations measured by a modern absolute gravimeter of the FG5 type are presented. The gravity observations were corrected for Earth tides, varying atmospheric pressure, polar motion, and ocean tide loading. The ocean tide loading corrections were subject to special attention. A model based on locally observed ocean tides was applied at some of the stations. The authors estimated the total uncertainties of the gravity values to range from 3 to 4 µgal (1 µgal = 10?8 m s?2). These errors are of magnitude one order less than previously presented absolute gravity values from Norway. The final gravity values are time tagged and will change due to postglacial rebound. The maximum effect is expected to be approximately ?1 µgal yr?1. 相似文献
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The results are presented from tidal gravity measurements at five sites in Europe using LaCoste and Romberg ET gravimeters. Improvements that we have made to the accuracies of these gravimeters are discussed. It is shown that the 'standard' calibration of the International Center for Earth Tides, used for worldwide tidal gravity profiles, is 1.2 per cent too high. The M2 and O1 observations are compared with model calculations of the Earth's body tide and ocean tide loading and it is shown that there is a very significant improvement in the agreement between observations and models compared to that obtained with previous tidal gravity measurements. For O1 , where the ocean tide loading and attraction in central Europe is only 0.4 per cent of the body tide, our measurements verify that the Dehant-Wahr anelastic body tide model gravimetric factor is accurate to 0.2 per cent. It is also shown that the effects of lateral heterogeneities in Earth structure on tidal gravity are too small to explain the large anomalies in previously published tidal gravity amplitudes. The observations clearly show the importance of conserving tidal mass in the Schwiderski ocean tide model. For sites in central Europe, the M2 and O1 observations and the models are in agreement at the 0.1 μgal (10−9 m s−2 ) level and tidal corrections to this accuracy can now be made to absolute gravity measurements. 相似文献
The results are presented from tidal gravity measurements at five sites in Europe using LaCoste and Romberg ET gravimeters. Improvements that we have made to the accuracies of these gravimeters are discussed. It is shown that the 'standard' calibration of the International Center for Earth Tides, used for worldwide tidal gravity profiles, is 1.2 per cent too high. The M
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本文首次报告了Lacoste&Romberg-EarthTide21地球潮汐重力仪在南极中山站记录到“不明地学事件”的情况,并对这种有待进一步证实的现象进行了简单描述和初步分析。 相似文献
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经1985年12月~1987年3月,三年度夏测绘科学考察,在中国南极长城站地区建立了一套完整的、精确的测绘基准系统。它包括大地坐标系统、高程系统和重力参考系统。本文叙述了建立这些基准系统的方法和数学模型,并分析了测量精度。 相似文献
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ShengKai Zhang DongChen E Fei Li JiFeng Huang YuanSheng Li ZeMin Wang XiaoHong Zhang 《寒旱区科学》2010,2(3):0198-0202
Tidal motion is the source of short-term vertical motion that an ice shelf experiences, and hence has a significant impact on ice shelves. During the 2003/2004 Austral summer season, five days of GPS measurements were carried out on the front of the Amery Ice Shelf (AIS), East Antarctica, by the 20th Chinese National Antarctica Research Expedition (CHINARE). The GPS data was processed using GAMIT/GLOBK software with 2-hour static data segment and the vertical precision is less than 0.18 m. To verify our results for the vertical component, we compare the ice shelf GPS tidal signal with a tidal result derived from tide gauge measurements at China's Zhongshan Station on Antarctica. Comparison of the GPS results with the tide gauge were in good agreement in amplitude at the few cm level, which indicates that the tide under the front of Amery Ice Shelf is irregular semidiurnal tide, the maximal tidal differences is approximately 2 m. GPS data can be used to validate the ocean tide model around the Antarctic area and such studies are important to improve our knowledge of the Antarctic ice shelf mass balance and dynamical models of ice sheet/ocean interaction. 相似文献
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Tidal gravity in Britain: tidal loading and the spatial distribution of the marine tide 总被引:1,自引:0,他引:1
T. F. Baker 《Geophysical Journal International》1980,62(2):249-267
Summary. Tidal gravity measurements have been made at six sites in Britain with two nulled LaCoste and Romberg Earth tide gravitymeters. The M 2 observations from these and two further sites are compared with calculations of the tidal loading from the seas around the British Isles and the major oceans. Models of the M 2 marine tides are convolved with Green's functions for appropriate radially stratified Earth models. The differences between the M 2 observations and the theoretical calculations are less than 0.6 μ gals and it is shown that these differences contain further information concerning the errors in the marine tide models. The M 2 marine tides on the north-west European continental shelf are reasonably well known and this allows a useful test of the feasibility of using tidal gravity measurements for the inverse ocean tide problem in areas where the ocean tides are less well known. The differential gravity loading signal between pairs of gravity stations is shown to be important for considerations of the uniqueness and accuracy of the inverse problem. M 2 tidal gravity loading maps for the British Isles and Europe have been produced which are of use in making corrections to various geodetic measurements. 相似文献
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南极区域潮汐是计算南极物质平衡和南极冰架表面冰流速的重要影响因素,同时对于研究冰架崩解和全球气候变暖具有重要作用。南极潮汐测量的方法从最初的实时测量,发展到了卫星测高和遥感监测以及建立数值模型预测的阶段。已有研究表明潮汐周期与冰架表面流速间存在一定关联,例如Filchner-Ronne冰架和Ross冰架的潮汐变化与冰流速度的联系为:在大潮时冰流速度达到最快,小潮时冰流速度达到最慢。研究还对南极典型冰架区域潮汐特征及对冰架表面冰流速、高程变化等的影响进行了总结。今后的研究不仅需要继续关注西南极和南极半岛的潮汐变化,更加需要对东南极稀疏的区域进行潮汐观测,这对于构建整个南极潮汐数据库和提高数值模型的精度具有重要意义。 相似文献
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MSA在冰芯深层的“迁移”现象的存在 ,关系到能否应用大气中 MSA季节特征进行极地冰芯断代 ,并以冰芯分析结果确定大气中生物硫化物含量的方法基础。本文展示各类最有代表性的冰雪 MSA剖面 ,对提出冰芯深层 MSA“迁移假说”的理论依据进行探讨 ,并根据最新资料 ,说明冰川中 MSA的“迁移”和重新分布 ,在表层粒雪和渗浸 -冻结冰层中同样可能发生。对“迁移假说”的延伸补充在于 ,粒雪中的 MSA迁移是在积雪中空气与外界贯通的“开放”条件下进行的 ,渗入雪层中的融水将 MSA溶出后 ,在晶粒间宏观向下输送 ,在阳离子集中的层位发生反应 ,生成盐类冰点的改变使之发生“冻结”,重新分布。而渗浸 -冻结冰层中的迁移机制可能和深层冰川冰中的情况接近 ,即在气体与外界隔绝条件下 ,主要在“封闭”的晶间脉状纹理中以“微观”形式进行。南极半岛 MSA迁移过程需要很长时间 ,而表层渗浸 -冻结冰层中 MSA迁移过程很快出现 ,说明冰中脉状纹理的加快形成、较高冰川温度和冰层中的较大含水量等因素会对 MSA“迁移”进程起促进作用。最后 ,对 MSA“迁移”情况下 ,如何进行有关冰芯 MSA计算进行了讨论 ,对设计实验验证并完善迁移理论提出了设想。 相似文献
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从1987年1月5日开始,在南极长城站使用挪威安德拉公司生产的WLR—5型水位计对潮汐进行长期自动观测,取得60天,共8千多组数据。本文对这些实测资料进行了分析,初步得出南极长城站潮汐变化的一些基本特征。 相似文献
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C. L. Pekeris 《Geophysical Journal International》1978,52(3):471-478
Summary. The theory of the bodily tide and of the yielding of the Earth to tidal loading is re-examined, with the purpose of checking the standard formula for the gravity tide which is used in the interpretation of tidal gravity measurements. Some remarks are made concerning the Green's function occurring in the theory of the gravity tide. 相似文献
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Monthly gravity solutions of the Gravity Recovery and Climate Experiment (GRACE) reveal three areas in Antarctica with striking interannual mass trends. The positive mass trend in Enderby Land, East Antarctica, is poorly understood because of uncertainties in the surface ice-sheet mass balance, post-glacial rebound (PGR), and processing of GRACE data. In this study, we compare the GRACE mass trends with values estimated from in situ snow-stake measurements, and Ice Cloud and land Elevation Satellite (ICESat) data. The mass trends estimated from ICESat data show a strong correlation with GRACE mass trends. In contrast, the snow-stake data show discrepancies with temporal variations in GRACE mass, especially in 2006. The discrepancies are probably associated with basal ice-sheet outflow, which is difficult to observe using snow stakes. We conclude that the bulk of the GRACE mass trend can be explained by snow accumulation and basal ice-sheet outflow. 相似文献
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The Grove Mountains are located in Princess Elizabeth Land,East Antarctica,ext ending from 72° to 73°S latitude and 73° to 76°E longitude,covering approxi mately 8000 km~2 areas.During the 2002/2003 austral summer season,the 19th CH INARE(Chinese National Antarctic Research Expedition)carried out the third expedition in Grove Mountains,East Antarctica.The Geodetic network was establ ished,which can provide ground control for the satellite image map for the mult i-discipline expedition in the Grove Mountains where seven permanent GPS benchm a rks were set up supported by the helicopter and snow vehicles.All GPS sites bes ides Z001 were observed at least for one hour using the dual frequencies Trimble 4000ssi GPS receivers.The data were processed by the comprehensive GPS analysi s package—GAMIT/GLOBK and the precision is good enough to satisfy with the acqu irement of satellite mapping in this area. 相似文献
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Self-consistent equilibrium ocean tides 总被引:4,自引:0,他引:4
Summary. We compute the static response of the world ocean to an external zonal gravitational potential. The computation includes the effects of the self-attraction of the ocean, and the yielding of the Earth caused both by the external potential and the change in ocean load. We compare the computed tide with measurements of the fortnightly and monthly ocean tides. The short-wavelength departures from equilibrium found by Wunsch are still present. An average of observations at Pacific islands shows that the fortnightly tide departs significantly from equilibrium but the monthly may not. We have also calculated the effects of our computed tide on measurements of tidal gravity and tidal fluctuations in the length of day. Existing tidal gravity data are too imprecise to enable us to determine whether or not the spatial average of the ocean tides departs from equilibrium. The length of day data suggest that the monthly tide is farther from equilibrium than the fortnightly. We have not been able to resolve the apparent discrepancy between the length of day and ocean tide data. 相似文献
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本文对南极菲尔德斯半岛夏季潮间带水温、盐度、营养盐(活性硅酸盐SiO3-Si、活性磷酸盐PO4-P、硝酸盐NO3-N)等环境因子的时空变化进行了分析讨论。其水温空间分布,高潮区最高,中潮区次之,低潮区最低;气温和潮间带裸露时间长短是影响潮间带水温变化的主要因子。盐度空间分布特点是高潮区最低,中潮区次之,低潮区最高,陆地融化雪水渗透到潮间带的多少将影响潮间带盐度的空间分布。潮间带营养盐含量的空间分布,中潮区低于低潮区,潮间带的营养盐主要不是来自陆源。 相似文献