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geoid Deformation and Elevation Influence Caused by Building Loading

Geo-Spatial Information Science 2009年第2期12卷 154-156页

作者：王解先季善标曹月玲余美义 Department of Surveying and Geo-informatics Tongji University

The paper studies the ground vertical deformation and the geoid undulation caused by loading of neighboring buildings, based on the loading tides theory. The influence on elevation is also considered. The results show that the ground vertical deformation and the geoid undulation both reach millimeter magnitude. Therefore, it is obvious that the building loading significantly affects the precise engineering surveying, and it must be seriously considered in application.

关键词： loading tides building loading ground deformation geoid undulation

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Local geoid Model Generation Using the Geometrical Approach

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Journal of Civil Engineering and Architecture 2021年第8期15卷 437-445页

作者： Mohammed Anwer Jassim Mohanad Mohsen Yousef Geomatics Engineering Department College of EngineeringSalahaddin University-ErbilErbil 44001Iraqi Kurdistan RegionIraq Duhok Polytechnical University—Zakho Technical Institute Duhok 42001Iraqi Kurdistan RegionIraq

The global navigation satellite systems(GNSS)provide an accurate three-dimensional positioning including the geodetic(ellipsoidal)height(h),which is,in most cases,must be transformed to the local/regional orthometric height(H)to have physically the desired meaning of the elevation above the national vertical datum(e.g.,MSL(Mean Sea Level)).Usually,the local orthometric heights are determined based on the value of geoid undulation(N),which is obtained by methods of gravimetrical observations or derived by methods of interpolation utilizing the local geoid models(LGM).The current paper highlights one of the methods of generating LGM that is based on the geometrical relationship between the global datum WGS84 and the Iraqi datum Karbala *** DGPS(Differential GPS)method is used to get the geodetic coordinates of about 97 selected points to cover the experimental area,within the boundaries of Erbil municipality,which has been partitioned into four ***,four LGM were generated individually for each one of the four parts with an estimated uncertainty equal to±0.076 m.

关键词： geoid undulation LGM ellipsoidal height Karbala 1979

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Impact of the formation and ablation of Antarctic ice sheet on the global geoid and sea level

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Chinese Journal of Polar Science 1998年第2期9卷 71-75页

作者：张赤军陆洋

It is convenient to investigate the gravimetry using a harmonic spheric function for the description of the distribution and thickness of the Antarctic ice sheet. The gravitational theory and the Stokes' harmonic spheric function formula were used to determine the impact of the Antarctic ice cap on the global geoid. The Antarctic ice cap is formed from the condensation of seawater vapour whose mass is equal to a layer of seawater 59 m thick of covering the earth's surface, i.e. 2.7×10 19 kg. This will cause the global averaged geoid to decrease for around 23 m. The authors' computations show that the Antractic ice cap has a great impact on the global geoid, which increases (+) in some regions, but decreases (-) in other reigions. The geoid is +115 m, -37 m and +8 m at the South Pole, the 25°S parallel and the North Pole, respectively. If the Antarctic ice cap melts completely, on the rigid Earth's surface the seawater and geoid will return to its original position (and height) due to the balancing force of the fluid. Since the crust is almost in a state of isostasy, assuming that the crust is an elastic solid and the mantle is an incompressible fluid, the load of seawater will deflect the crust and drive the mantle material to flow. The material above the isostatic surface compensates mutually. If the densities of the mantle and seawater are 3270 kg/m 3 and 1030 kg/m 3, respectively, then the variation in the elevation of the continent is only 2.8 m with respect to the sea level after the Antarctic ice cap melts;it is not larger than that estimated by some *** is worth noting that the above results were derived from an ideal Earth model. In the real Earth, the mantle and crust are visco elastic.

关键词： Antarctic ice sheet geoid undulation relative change of sea level.

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