共查询到19条相似文献，搜索用时 125 毫秒
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《武汉大学学报(信息科学版)》2005,(11)
日前,国家测绘局正式公布了2005年珠穆朗玛峰高程测量获得的最新数据:珠穆朗玛峰峰顶岩石面海拔高程8844.43米。参数:珠穆朗玛峰峰顶岩石面高程测量精度±0.21米;峰顶冰雪深度3.50米。这一数据与1975年相比,高度降低约3.7米。同时,原1975年公布的珠峰高程数据停止使用。2005珠穆朗玛峰高程测量工作经过艰苦的外业实测和周密、精确的内业计算及检验,获得了珠峰峰顶的高程数据。经专家评审认为,这组数据是迄今为止国内乃至国际上历次珠峰高程测量中最为详尽、精确的数据。珠穆朗玛峰最新海拔高程8844.43米… 相似文献
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为了分析2020与2005珠峰高程测量与确定过程中的异同，该文从GNSS数据处理、高程控制网数据处理、峰顶交会数据处理、峰顶大地水准面差距计算4个方面对其进行了异同比较分析，阐述了2020珠峰高程测量的技术进步与创新。分析表明，2020珠峰高程测量从测量装备的国产化、测量手段和数据的丰富性，数据处理的高精度等多个方面，较2005年都有长足的进步。同时，中尼合作开展数据处理，共同确定了基于国际高程参考系统(international height reference system, IHRS)的珠峰正高。 相似文献
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20世纪60年代以来，我国单独或与外国合作，在1966年、1975年、1992年、1998年、1999年和2005年对珠穆朗玛峰（以下简称珠峰）的高程及其北坡的地壳运动进行了6次大规模的大地测量，其中包括天文、重力、平面、高程和大气折射等方面的外业作业、数据处理和科学研究。本文对我国上述几次测量中的GPS和水准测量等数据进行了综合，对珠峰峰顶雪面高程值的变化和该地区地壳的水平运动和垂直运动进行了撂索。根据1992年和2005年的GPS测量，珠峰峰项雪面高程的变化在13a闻约下降25cm，平均年下降率为1．8cm。根据1992-2005年间的三次GPS测量，珠峰北坡地区的地壳水平运动平均每年以4cm的速度向北东45。方向推进。根据1966-2005年的多期水准测量，该地区的地壳垂直运动平均每年上升1.8mm。此外，若从以上各个时间段作进一步分析，则发现珠峰北坡地壳的水平运动和垂直运动在时间上和空间上都存在非平稳性。 相似文献
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介绍了雷达探测技术（GPR）原理及其与GPS集成的峰顶专用雷达探测设备和测量情况。经过对测量数据的处理与分析，获得峰顶觇标处的冰雪层厚度为3．50m，为珠穆朗玛峰岩石面高程的确定提供了可靠参数。 相似文献
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2020珠峰高程测量,首次确定并发布了基于国际高程参考系统(IHRS)的珠峰正高。在珠峰地区实现国际高程参考系统,采用的方案是建立珠峰区域高精度重力大地水准面。利用地球重力场谱组合理论和基于数据驱动的谱权确定方法,测试优选参考重力场模型及其截断阶数和球冠积分半径等关键参数,联合航空和地面重力等数据建立了珠峰区域重力似大地水准面模型,61点高精度GNSS水准高程异常检核表明,模型精度达3.8 cm,加入航空重力数据后模型精度提升幅度达51.3%。提出顾及高差改正的峰顶高程异常内插方法,采用顾及地形质量影响的高程异常——大地水准面差距转换改正严密公式,使用峰顶实测地面重力数据,基于国际高程参考系统定义的重力位值W0和GRS80参考椭球,最终确定了国际高程参考系统中的高精度珠峰峰顶大地水准面差距。 相似文献
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Local geoid determination combining gravity disturbances and GPS/levelling: a case study in the Lake Nasser area, Aswan, Egypt 总被引：1，自引：0，他引：1
C. C. Tscherning Awar Radwan A. A. Tealeb S. M. Mahmoud M. Abd El-Monum Ramdan Hassan I. El-Syaed K. Saker 《Journal of Geodesy》2001,75(7-8):343-348
The use of GPS for height control in an area with existing levelling data requires the determination of a local geoid and
the bias between the local levelling datum and the one implicitly defined when computing the local geoid. If only scarse gravity
data are available, the heights of new data may be collected rapidly by determining the ellipsoidal height by GPS and not
using orthometric heights. Hence the geoid determination has to be based on gravity disturbances contingently combined with
gravity anomalies. Furthermore, existing GPS/levelling data may also be used in the geoid determination if a suitable general
gravity field modelling method (such as least-squares collocation, LSC) is applied. A comparison has been made in the Aswan
Dam area between geoids determined using fast Fourier transform (FFT) with gravity disturbances exclusively and LSC using
only the gravity disturbances and the disturbances combined with GPS/levelling data. The EGM96 spherical harmonic model was
in all cases used in a remove–restore mode. A total of 198 gravity disturbances spaced approximately 3 km apart were used,
as well as 35 GPS/levelling points in the vicinity and on the Aswan Dam. No data on the Nasser Lake were available. This gave
difficulties when using FFT, which requires the use of gridded data. When using exclusively the gravity disturbances, the
agreement between the GPS/levelling data were 0.71 ± 0.17 m for FFT and 0.63 ± 0.15 for LSC. When combining gravity disturbances
and GPS/levelling, the LSC error estimate was ±0.10 m. In the latter case two bias parameters had to be introduced to account
for a possible levelling datum difference between the levelling on the dam and that on the adjacent roads.
Received: 14 August 2000 / Accepted: 28 February 2001 相似文献
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Fast and accurate relative positioning for baselines less than 20 km in length is possible using dual-frequency Global Positioning
System (GPS) receivers. By measuring orthometric heights of a few GPS stations by differential levelling techniques, the geoid
undulation can be modelled, which enables GPS to be used for orthometric height determination in a much faster and more economical
way than terrestrial methods. The geoid undulation anomaly can be very useful for studying tectonic structure. GPS, levelling
and gravity measurements were carried out along a 200-km-long highly undulating profile, at an average elevation of 4000 m,
in the Ladak region of NW Himalaya, India. The geoid undulation and gravity anomaly were measured at 28 common GPS-levelling
and 67 GPS-gravity stations. A regional geoid low of nearly −4 m coincident with a steep negative gravity gradient is compatible
with very recent findings from other geophysical studies of a low-velocity layer 20–30 km thick to the north of the India–Tibet
plate boundary, within the Tibetan plate. Topographic, gravity and geoid data possibly indicate that the actual plate boundary
is situated further north of what is geologically known as the Indus Tsangpo Suture Zone, the traditionally supposed location
of the plate boundary. Comparison of the measured geoid with that computed from OSU91 and EGM96 gravity models indicates that
GPS alone can be used for orthometric height determination over the Higher Himalaya with 1–2 m accuracy.
Received: 10 April 1997 / Accepted: 9 October 1998 相似文献
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利用我国实测重力值计算完成了全国５＇×５＇格网平均空间重力异常，并结合重力场模型ＷＤＭ９４，利用国内外最新发展起来的快速谱算法确定了我国高分辨率５＇×５＇重力大地水准面ＷＺＤ９４。 相似文献
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A new technique to determine geoid and orthometric heights from satellite positioning and geopotential numbers 总被引：1，自引：0，他引：1
L. E. Sjöberg 《Journal of Geodesy》2006,80(6):304-312
This paper takes advantage of space-technique-derived positions on the Earth’s surface and the known normal gravity field to determine the height anomaly from geopotential numbers. A new method is also presented to downward-continue the height anomaly to the geoid height. The orthometric height is determined as the difference between the geodetic (ellipsoidal) height derived by space-geodetic techniques and the geoid height. It is shown that, due to the very high correlation between the geodetic height and the computed geoid height, the error of the orthometric height determined by this method is usually much smaller than that provided by standard GPS/levelling. Also included is a practical formula to correct the Helmert orthometric height by adding two correction terms: a topographic roughness term and a correction term for lateral topographic mass–density variations. 相似文献
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GRACE、GOCE卫星重力计划的实施,对确定高精度重力场模型具有重要贡献。联合GRACE、GOCE卫星数据建立的重力场模型和我国均匀分布的649个GPS/水准数据可以确定我国高程基准重力位,但我国高程基准对应的参考面为似大地水准面,是非等位面,将似大地水准面转化为大地水准面后确定的大地水准面重力位为62 636 854.395 3m~2s~(-2),为提高高阶项对确定大地水准面的贡献,利用高分辨率重力场模型EGM2008扩展GRACE/GOCE模型至2190阶,同时将重力场模型和GPS/水准数据统一到同一参考框架和潮汐系统,最后利用扩展后的模型确定的我国大地水准面重力位为62 636 852.751 8m~2s~(-2)。其中组合模型TIM_R4+EGM2008确定的我国85高程基准重力位值62 636 852.704 5m~2s~(-2)精度最高。重力场模型截断误差对确定我国大地水准面的影响约16cm,潮汐系统影响约4~6cm。 相似文献
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The rigorous determination of orthometric heights 总被引：1，自引：2，他引：1
The main problem of the rigorous definition of the orthometric height is the evaluation of the mean value of the Earth’s gravity acceleration along the plumbline within the topography. To find the exact relation between rigorous orthometric and Molodensky’s normal heights, the mean gravity is decomposed into: the mean normal gravity, the mean values of gravity generated by topographical and atmospheric masses, and the mean gravity disturbance generated by the masses contained within geoid. The mean normal gravity is evaluated according to Somigliana–Pizzetti’s theory of the normal gravity field generated by the ellipsoid of revolution. Using the Bruns formula, the mean values of gravity along the plumbline generated by topographical and atmospheric masses can be computed as the integral mean between the Earth’s surface and geoid. Since the disturbing gravity potential generated by masses inside the geoid is harmonic above the geoid, the mean value of the gravity disturbance generated by the geoid is defined by applying the Poisson integral equation to the integral mean. Numerical results for a test area in the Canadian Rocky Mountains show that the difference between the rigorously defined orthometric height and the Molodensky normal height reaches ∼0.5 m. 相似文献
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Geoid determination using one-step integration 总被引：1，自引：1，他引：0
P. Novák 《Journal of Geodesy》2003,77(3-4):193-206
A residual (high-frequency) gravimetric geoid is usually computed from geographically limited ground, sea and/or airborne gravimetric data. The mathematical model for its determination from ground gravity is based on the transformation of observed discrete values of gravity into gravity potential related to either the international ellipsoid or the geoid. The two reference surfaces are used depending on height information that accompanies ground gravity data: traditionally orthometric heights determined by geodetic levelling were used while GPS positioning nowadays allows for estimation of geodetic (ellipsoidal) heights. This transformation is usually performed in two steps: (1) observed values of gravity are downward continued to the ellipsoid or the geoid, and (2) gravity at the ellipsoid or the geoid is transformed into the corresponding potential. Each of these two steps represents the solution of one geodetic boundary-value problem of potential theory, namely the first and second or third problem. Thus two different geodetic boundary-value problems must be formulated and solved, which requires numerical evaluation of two surface integrals. In this contribution, a mathematical model in the form of a single Fredholm integral equation of the first kind is presented and numerically investigated. This model combines the solution of the first and second/third boundary-value problems and transforms ground gravity disturbances or anomalies into the harmonically downward continued disturbing potential at the ellipsoid or the geoid directly. Numerical tests show that the new approach offers an efficient and stable solution for the determination of the residual geoid from ground gravity data. 相似文献