مناسب سازی و پالایش پایگاه اطلاعات گرانش ایران

نوع مقاله: مقاله پژوهشی

نویسنده

انستیتوی فنی سلطنتی KTH ، دپارتمان ژئودزی


عنوان مقاله [English]

QUALIFICATION AND REFINEMENT OF THE IRANIAN GRAVITY DATABASE

نویسنده [English]

  • Ramin Kiamehr
Royal Institute of Technology (KTH), Geodesy Division , SE-100 44 Stockholm , Sweden
چکیده [English]

Since 1986 several gravimetric geoid models were published in the Iran region. Based on primary investigation on these gravimetric geoid models, it is found that their relative and absolute accuracies versus GPS/levelling are more or less the same or in some cases worse than the current available global geopotential models (Kiamehr 1997,2003 ,2001a , 2003b, 2004 and Kiamehr and Sjöberg 2004). Regardless the effect of choosing proper computational method in determination of any geoid models, the quantity and quality of the gravity anomaly database plays a major rule in the final result of them. The main aim of this research is the creation of a more complete and also refined new gravity database for Iran. For this purpose different dataset from different sources are gathered and combined in a single database. Then we start to refine it from possible outliers by using Least Squares Collocation (LSC) approach. A special method used for the interpolation scheme of free-air gravity anomalies in order to take into account the effect of topography. The final grid file was creates based on the Kriging method with 80" * 90" resolution. The overall accuracy for the current database is estimated to near 10 mGal.

کلیدواژه‌ها [English]

  • Least Squares Collocation
  • Gravity Anomaly
  • Outlier
  • RTM
  • Geoid
1- BGI (1992) BGI Bulletin d' Information Vol 70,71.
2- Forsberg, R. (1984) A Study of Terrain Reductions, Density Anomalies and Geophysical Inversion Methods in Gravity Fiels Modelling. Rep 355, Dept Geod Sci, Ohio State Univ, Columbus
3- Forsberg, R. (2001) Development of a Nordic cm-geoid-with basics of geoid determination. In:
Harsson BG (ed.) Lecture notes for autumn school organised by the Nordic Geodetic Commission. held in Fevik, Norway , 28 Aug, - 2 Sept. 2000, statens kartverk. HØnefoss , Norway.
4- Heiskanen, W.A., Moritz, H. (1967) Physical Geodesy . W H Freeman and Co., New York , London and San Francisco.
5- Kiamehr, R. (1997) Iranian geoid problem and recommendation , 1997, 4th International Conferences of civil engineering , Sharif University of Technology , Tehran, Iran.
6- Kiamehr, R. (2001) Potential of Iranian geoid for GPS / Leveling, National Cartographic Center of Iran Geomatics 80 conferences, Tehran , Iran.
7- Kiamehr , R., 2003a, Comparison relative accuracy of EGM96 and Iranian gravimetric geoid, 6Th International conference of Civil Eng., Isfahan University of Technology, Iran.
8- Kiamehr, R., 2003b, Discussion about relative accuracy of IFAG geoid, J. Sepehr Iranian National Geography Organization (NGO), 42: 13-18.
9- Kiamehr, R., 2004, The Relative Accuracies of Recent Satellite Gravimetric Models in Iran, IAG International Symposium Gravity, Geoid and Space Missions - GGSM2004, Porto , Portugal.
10- Kiamehr, R. and Sjöberg LE (2004) The qualities of Iranian gravimetric geoid models versus recent gravity field missions, Submitted J. Studia Geophysica et Geodaetica.
11- Kiamehr, R. and Sjöberg, L.E.(2005) Effect of the SRTM global DEM in the determination of a high-resolution geoid model of Iran , Submitted J.Geodesy.
12- Kiamehr, R. (2005) Hybrid precise gravimetric geoid model for Iran based on recent GRACE and SRTM data and the Least Squares Modification of Stoke Formula, submitted to J.Geodesy.
13- Lemoine , F.G., Kenyon , S.C., Factor , J.K., Trimmer R.G., Pavlis, N.K., Chinn, D.S., Cox C.M., Klosko, S.B., Luthcke, S.B., Torrence , M.H., Wang Y.M., Williamson , R.G., Pavlis, E.C., Rapp, R.H., Olson, T.R. (1998) The Development of the Joint NASA GSFC and NIMA Geopotential Model EGM96. NASA Goddard Space Flight Center , Greenbelt , Maryland, 20771 USA.
14- Moritz, H. (1992) Geodetic Reference System 1980, Bull Geod , 66: 187 - 192.
15- Sandwell, D.T., Smith, W.H.F (1997) Marine gravity anomaly from Geosat and ERS 1 satellite altimetry , Journal of Geophysical Research , v. 102, No. B5 , p. 10039-10054.
16- Sjöberg , L.E. (2003) A solution to the downward continuation effect on the geoid determined by Sroke's formula. J Geod 77: 94-100.
17- Tscherning , C.C., Rapp, R.H. (1974) Closed Co variance Expressions for Gravity Anomalies , Geoid Undulations, and Deflections of the Vertical Implied by Anomaly Degree - Variance Models. Rep of the Dept of Geodetic Sci and Surv No 208 The Ohio State Univ, Columbus, Ohio.
18- Vermeer, M. (1995) Mass point geopotential modelling using fast spectral techniques ; historical overview , toolbox description, numerical experiment, manuscripta geodaetica, 20: 362-378.
19- Agren, J. (2004) Regional geoid determination methods for the era of satellite gravimetry , Ph.D. thesis , Royal Institute of Technology, Stockholm, Sweden.