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Qualification and refinement of the gravity database based on cross-validation approach, A case study of Iran
KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
2007 (English)In: Acta Geodaetica et Geophysica, ISSN 1217-8977, Vol. 42, no 3, 285-295 p.Article in journal (Refereed) Published
Abstract [en]

In this article, we propose a technique for the precise cleaning of the gravity anomaly database based on the cross validation approach. The terrestrial gravity anomalies were compared versus a global geopotential model and take into account the effect of topography in this comparison. The efficiency of the cross-validation technique is illustrated in outlier detection as well as in choosing the proper gridding technique as a case study in construction of the Iranian new gravity database. In order to reduce the effect of topography and the discretisation error, a special interpolation scheme is used for gridding of the free-air gravity anomalies. The final grid file was created based on the Kriging method with 80" x 90" block resolution. The overall accuracy for the new Iranian gravity database is estimated in the order of 10 mGal.

Place, publisher, year, edition, pages
2007. Vol. 42, no 3, 285-295 p.
Keyword [en]
cross-validation; geoid; gravity anomaly; Iran; outlier; residual terrain model
National Category
Earth and Related Environmental Sciences
Identifiers
URN: urn:nbn:se:kth:diva-6190DOI: 10.1556/AGeod.42.2007.3.3ISI: 000258337800003Scopus ID: 2-s2.0-34548009131OAI: oai:DiVA.org:kth-6190DiVA: diva2:10831
Note
QC 20100906Available from: 2006-10-03 Created: 2006-10-03 Last updated: 2010-09-06Bibliographically approved
In thesis
1. Precise Gravimetric Geoid Model for Iran Based on GRACE and SRTM Data and the Least-Squares Modification of Stokes’ Formula: with Some Geodynamic Interpretations
Open this publication in new window or tab >>Precise Gravimetric Geoid Model for Iran Based on GRACE and SRTM Data and the Least-Squares Modification of Stokes’ Formula: with Some Geodynamic Interpretations
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Iran is one of the most complicated areas in the world from the view of rough topography, tectonic activity, large lateral density and geoidal height variations. The computation of a regional gravimetric geoid model with high accuracy in mountainous regions, especially with sparse data, is a difficult task that needs a special attention to obtain reliable results which can meet the needs of the today geodetic community.

In this research different heterogeneous data has been used, which includes gravity anomalies, the high-resolution SRTM Digital Elevation Model (DEM), recently published GRACE Global Geopotential Models (GGMs), geological maps and GPS/levelling data. The above data has been optimally combined through the least-squares modification of Stokes formula with additive corrections. Regarding the data evaluation and refinement, the cross-validation technique has been used for detection of outliers. Also, several GGMs and DEMs are evaluated with GPS/levelling data. The impact of utilizing a high resolution SRTM DEM to improve the accuracy of the geoid model has been studied. Also, a density variation model has been established, and its effect on the accuracy of the geoid was investigated. Thereafter a new height datum for Iran was established based on the corrective surface idea. Finally, it was found that there is a significant correlation between the lateral geoid slope and the tectonic activities in Iran.

We show that our hybrid gravimetric geoid model IRG04 agrees considerably better with GPS/levelling than any of the other recent local geoid models in the area. Its RMS fit with GPS/levelling is 27 cm and 3.8 ppm in the absolute and relative senses, respectively. Moreover, the relative accuracy of the IRG04 geoid model is at least 4 times better than any of the previously published global and regional geoid models in the area. Also, the RMS fit of the combined surface model (IRG04C) versus independent precise GPS/levelling is almost 4 times better compared to the original gravimetric geoid model (IRG04). These achievements clearly show the effect of the new gravity database and the SRTM data for the regional geoid determination in Iran based on the least-squares modification of Stokes’ formula.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. viii, 89 p.
Series
TRITA-INFRA, ISSN 1651-0216 ; 06-003
Keyword
Gravity database, least-squares modification of Stokes, geoid determination, SRTM, GRACE, GPS/levelling, density variation model, height datum, geodynamics, Iran
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-4125 (URN)978-91-85539-06-2 (ISBN)
Public defence
2006-10-27, D1, Lindstedtsvägen 17, 2tr, 13:00
Opponent
Supervisors
Note

QC 20100906

Available from: 2006-10-03 Created: 2006-10-03 Last updated: 2017-02-23Bibliographically approved

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