Regional geopotential model improvement for the Iranian geoid determination

Weber, Georg F.; Zomorrodian, Hossein

doi:10.1007/bf02519221

Cited by 30 publications

(11 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The computation of the first Iranian geoid model was conducted jointly by the Institut für Angewandte Geodäsie (IfAG), Germany, the Institute of Geophysics, Tehran University (IGTU) and the National Cartographic Centre of Iran (NCC), using a regional geopotential model improvement approach (Weber and Zomorrodian, 1988) based on the GPM2 global geopotential model (Wenzel, 1985).…”

Section: Overview Of Current Iranian Gravimetric Geoid Modelsmentioning

confidence: 99%

Comparison of the qualities of recent global and local gravimetric geoid models in Iran

Kiamehr

Sjöberg

2005

Stud Geophys Geod

View full text Add to dashboard Cite

A number of regional gravimetric geoid models have recently been determined for the Iran area, and a common problem is to select the best model, e.g. for engineering applications. A related problem is that in order to improve the local geoid models, the selection of the best Global Geopotential Model (GGM) model for the region is essential, to be used in a combined solution from GGM and local gravimetric data. We discuss these problems by taking advantage of 260 GPS/levelling points as an external tool for validation of different global and local geoid models in the absolute and relative senses. By using relative comparisons of the height differences between precise levelling and GPS/geoid models we avoid possible unknown systematic effects between the different types of observables.The study shows that the combination of the newly released GRACE model (GGM02C) with EGM96 geoid model fits the GPS/levelling data in Iran with the best absolute and relative accuracy among the GGMs. Among the local geoid models, the newly gravimetric geoid model IRG04 agrees considerably better with GPS/levelling than any of the other recent local geoid models. Its rms fit with GPS/levelling is 55 cm. Hence, we strongly recommend the use of this new model in any surveying engineering or GPS/levelling projects in the area.

show abstract

Section: Overview Of Current Iranian Gravimetric Geoid Modelsmentioning

confidence: 99%

Comparison of the qualities of recent global and local gravimetric geoid models in Iran

Kiamehr

Sjöberg

2005

Stud Geophys Geod

View full text Add to dashboard Cite

show abstract

“…For a brief introduction on the background of geoid modeling in Iran, the last gravimetric geoid models released from 1988 are mentioned. They include the models IRGeoid88 (Weber and Zomorrodian 1988), IRgeoid01 (Ardalan et al 2001), IRGeoid05a (Safari et al 2005), IRGeoid05b (Nahavandchi and Soltanpour 2005), IRGeoid06 (Kiamehr 2006), and finally IRGeoid10 (Hatam Chavari 2010), which were developed over the last three decades to improve the precision of geoids over Iran. The most recent model, IRGeoid10, is a gravimetric geoid introduced by Hatam Chavari (2010) for Iranian territory (25°≤ f ≤ 40°and 44°≤ l ≤ 64°) on a 3 Â 3-arc-min grid using the remove-restore technique and the Helmert's second condensation method.…”

Section: Gravimetric Geoid Model Irgeoid10mentioning

confidence: 99%

Combination of GPS and Leveling Observations and Geoid Models Using Least-Squares Variance Component Estimation

et al. 2017

View full text Add to dashboard Cite

In the last few years, satellite-based positioning techniques, such as the Global Positioning System (GPS), proved their abilities in various geodetic fields. Height determination, as one of such applications, requires a more likely correct geoid model to provide reliable geoid heights for transformation of the ellipsoidal heights to orthometric heights. An important step is then to establish such a model by optimal combination of the available geoid models. This can be achieved via variance component estimation (VCE) methods, which provide appropriate weights to GPS and leveling observations as well as the geoid models. The authors demonstrate the efficacy of the least-squares VCE (LS-VCE) to this problem. The algorithm is applied to real data sets in Shahin-Shahr, Isfahan, Iran, to evaluate the EGM2008 and GGMplus Earth geopotential models and a regional geoid model (named IRGeoid10) in terms of agreement to the GPS/leveling observations and introduce the more likely correct model over the case-study area. The results indicate that the EGM2008 model shows a good agreement (2-mm precision on the fitted surface) with the results of the GPS/leveling observations in this very small area. It is notable, however, that the present contribution is mainly of interest from an algorithmic point of view because concrete conclusions cannot be made when comparing the results due to the small case-study area used. By optimal combination of these data sets, the weights of which are estimated by LS-VCE, a geometric surface is presented to approximate the local vertical datum in the case-study region. This surface can convert the ellipsoidal heights, which can be obtained from GPS, to the orthometric heights with high precision. individual papers. This paper is part of the Journal of Surveying Engineering, © ASCE, ISSN 0733-9453. © ASCE 04016023-1 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016023-9 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016023-11 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16.

show abstract

“…The reader may refer, e.g., to Weber and Zomorrodian (1988), Wenzel (1998), Abd-Elmotaal (2007), AbdElmotaal et al (2014).…”

Section: Introduction and Basic Ideamentioning

confidence: 98%

Establishment of the Gravity Database AFRGDB_V1.0 for the African Geoid

Abd-Elmotaal

Seitz

Kühtreiber

et al. 2015

International Association of Geodesy Symposia

View full text Add to dashboard Cite

In the framework of the IAG African Geoid Project it is needed to have a uniform gridded gravity data set to compute the geoid using Stokes' integral in the frequency domain by 1-D FFT technique. The available gravity data set consists of land point gravity data as well as shipborne and altimetry derived gravity anomaly data. The available gravity data set has a lot of significant gaps allover the continent. The establishment of the gravity database AFRGDB_V1.0 for the African geoid has been carried out using an iterative process employing a tailored reference model and weighted least-squares prediction technique. The point gravity data on land has got the highest precision, while the shipborne and altimetry gravity data got a moderate precision. In each iteration step, the data gaps are filled with the tailored reference model computed at the previous iteration step, getting the lowest precision within the prediction technique. The weighted least-squares prediction technique is thus carried out to estimate gridded gravity anomalies, which are used to estimate a new tailored reference model employing two harmonic analysis techniques. The gravity database on a uniform grid size of 5 0 5 0 has been established by the developed process. It has been validated with real data. A standard deviation of the residuals is about 9 mgal. 68% of the data points have residuals less than 4 mgals.

show abstract

Regional geopotential model improvement for the Iranian geoid determination

Cited by 30 publications

References 5 publications

Comparison of the qualities of recent global and local gravimetric geoid models in Iran

Comparison of the qualities of recent global and local gravimetric geoid models in Iran

Combination of GPS and Leveling Observations and Geoid Models Using Least-Squares Variance Component Estimation

Establishment of the Gravity Database AFRGDB_V1.0 for the African Geoid

Contact Info

Product

Resources

About