Reliability of CHAMP Anomaly Continuations

  • Ralph R.B. von Frese
  • Hyung Rae Kim
  • Patrick T. Taylor
  • Mohanmmad F. Asgharzadeh

Summary

CHAMP is recording state-of-the-art magnetic and gravity field observations at altitudes raging over roughly 300–550 km. However, the non-uniqueness of the process and satellite anomaly errors severely limit anomaly continuation. Indeed, our numerical anomaly simulations from satellite to airborne altitudes show that effective downward continuations of the CHAMP data are restricted to within approximately 50 km of the observation altitudes while upward continuations can be effective over a somewhat larger altitude range. The great unreliability of downward continuation requires that the satellite geopotential observations must be analyzed at satellite altitudes if the anomaly details are to be exploited most fully. Given current anomaly error levels, multi-field inversion of satellite and near-surface anomalies is the best approach for implementing satellite geopotential observations for subsurface studies. We demonstrate the power of this approach using a crustal model obtained by the inversion of combined near-surface and satellite magnetic anomalies for Maud Rise, Antarctica, in the southwestern Indian Ocean. Our modeling, which also includes regional gravity constraints, suggests that crustal thickness variations and remanent magnetization of the normal polarity Cretaceous Quiet Zone produce the dominant satellite altitude magnehtic anomalies.

Key words

anomaly continuation Maude Rise Antarctica ADMAP CHAMP Ørsted 

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References

  1. 1.
    von Frese R R B, Kim H R, Tan L, Kim J W, Taylor P T, Purucker M E, Alsdorf D E and Raymond C A (1999) Satellite magnetic anomalies of the Antarctic cmrst. Annali di Geofisica 42: 309–326.Google Scholar
  2. 2.
    Gubbins D, and J Bloxharn (1985) Geomagnetic field analysis, III, Magnetic fields on the core-mantle boundary. Geophys J R Astron Soc 80: 695–713.Google Scholar
  3. 3.
    Llubes M, Florsch N, Legresy B, Lemoine J-M, Loyer S, Crossley D and Réiny F (2003) Crustal thickness in Antarctica fiom CHAMP gravirnetery. Earth Planet Sci Lett 212: 103–117.CrossRefGoogle Scholar
  4. 4.
    von Frese R R B, Hinze W J and Braile L W (1981) Spherical earth gravity and magnetic anomaly analysis by equivalent point source inversion. Earth Planet Sci Lett 53:69–83.CrossRefGoogle Scholar
  5. 5.
    von Frese R R B, Hinze W J, Braile L W and Luca A J (1981) Spherical earth gravity and magnetic anomaly modeling by Gauss-Legendre quadrature integration. J Geophys 49: 234–242.Google Scholar
  6. 6.
    Langel R A, and Estes R H (1985) The near-earth geomagnetic field at 1980 determined from Magsat data. J Geophys Res 90: 2,495–2,510.Google Scholar
  7. 7.
    Ravat, D, Whaler KA, Pilkington M, Sabaka T, and Purucker M (2002) Compatibility of high-altitude aeromagnetic and satellite-altitude magnetic anomalies over Canada. Geophysics 67: 546–554.CrossRefGoogle Scholar
  8. 8.
    Alsdorf D E, and von Frese R R B (1994) Fortran Programs for Processing Magsat Data for Lithospheric, External Field and Residual Core Components. NASA-GSFCTM104612, 196 pp.Google Scholar
  9. 9.
    Kimn H R (2002) Antarctic Lithospheric Anomalies from Ørsted Satellite and Near-Surface Magnetic Observations. Ph.D. Dissertation (unpubl.), The Ohio State University, Colaumbus, 160 pp.Google Scholar
  10. 10.
    Golynsky A, Chiappini M, Damaske D, Ferraccioli F, Fenis J Finn C, Ghidella M, Isihara T, Johnson A, Kim H R, Kovacs L, LaBrecque J, Masolov V, Nogi Y, Purucker M, Taylor P and Torta M (2001) ADMAP — Magnetic Anomaly Map of the Antarctic, 1:10,000,000 scale map. in: Morris P and von Frese R. eds, BAS (Misc.) 10, Cambridge, British Antarctic Survey.Google Scholar
  11. 11.
    Kim H R, von Frese R R B, Kim J W, Taylor P T, Purucker M E and Neubert T (2002) Ørsted verifies regional magnetic anomalies of the Antarctic lithosphere. Geophys Res Lert 29(15): ORS 3-1 to 3-3.Google Scholar
  12. 12.
    von Frese R R B, Tan L, Kim J W and Bentley C R (1999) Antarctic crustal modeling from the spectral correlation of free-air gravity anomalies with the terrain. J Geophys Res 104: 25275–25296.CrossRefGoogle Scholar
  13. 13.
    Bormann P, Bankwitz P, Bankwitz E, Damm V, Hurtig E, Kompf H, Menning M, Paech H-J, Schofer U and Stackegrandt W (1986) Structure and development of the passive continental margin across the Princess Astrid coast East Antarctica. J Geodyn 6: 347–373CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Ralph R.B. von Frese
    • 1
  • Hyung Rae Kim
    • 2
  • Patrick T. Taylor
    • 3
  • Mohanmmad F. Asgharzadeh
    • 1
  1. 1.Dept. of Geological SciencesThe Ohio State UniversityColumbusUSA
  2. 2.UMBC/GEST and Geodynamics Branch, NASA'GSFCGreenbeltUSA
  3. 3.Geodynamics Braich, NASA/GSFCGreenbeltUSA

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