Impact Estimation and Filtering of Disturbances in FG5 Absolute Gravimeter Observations

Affiliation(s)

Department of Geosciences, School of Natural Sciences and Mathematics, The University of Texas at Dallas, Richardson, USA.

Department of Geosciences, School of Natural Sciences and Mathematics, The University of Texas at Dallas, Richardson, USA.

ABSTRACT

Instrumental and environmental disturbances do affect FG5 absolute gravimeter observations and the estimated gravity values, sometimes to the degree that entire measurement campaigns are discarded. We propose a method which moves towards the re-assessment of previously discarded observations. Once an estimate of the frequency and amplitude of a disturbance in a FG5 data set exists, the proposed method can estimate its impact on the estimated gravity value. This is performed through a Gaussian Bell Summation approach of the functional relationship between disturbance frequency and standard deviation of gravity. The filtering of the identified disturbance is realized through a modification of the functional model of the equation of motion in the least squares adjustment of FG5 observations. The results reveal that the Gaussian Bell Summation approximates the frequency—gravity impact relationship sufficiently well with negligible uncertainties, while the accuracy of the detected disturbance frequency defines a limiting factor for the gravity impact estimation. A realistic disturbance of 15 Hz with an amplitude of 1.5 nm had an impact of ≈48 [μGal] on the gravity estimate. The proposed filter approach reduced the impact to ≈12 [μGal], with the remaining effect being almost entirely associated to the uncertainty in disturbance frequency detection.

Cite this paper

M. Orlob and A. Braun, "Impact Estimation and Filtering of Disturbances in FG5 Absolute Gravimeter Observations,"*International Journal of Geosciences*, Vol. 4 No. 2, 2013, pp. 302-308. doi: 10.4236/ijg.2013.42028.

M. Orlob and A. Braun, "Impact Estimation and Filtering of Disturbances in FG5 Absolute Gravimeter Observations,"

References

[1] H. Hanada, T. Tsubokawa and S. Tsuruta. “Possible Large Systematic Error Source in Absolute Gravimetry,” Metrologia, Vol. 33, No. 2, 1996, pp. 155-160. doi:10.1088/0026-1394/33/2/4

[2] G. Durando and G. Mana, “Propagation of Error Analysis in a Total Least-Squares Estimator in Absolute Gravimetry,” Measurment Science & Technology, Vol. 13, No. 10, 2002, pp. 1505-1511. doi:10.1088/0957-0233/13/10/301

[3] C. Rothleitner and O. Francis, “On the Influence of the Rotation of a Corner Cube Reflector in Absolute Gravimetry,” Metrologia, Vol. 47, No. 5, 2010, pp. 567-574. doi:10.1088/0026-1394/47/5/007

[4] F. J. Klopping, G. Peter, D. S. Robertson, K. A. Berstis, R. E. Moose and W. E. Carter, “Improvements in Absolute Gravity Oberservations,” Journal of Geophysical Research, Vol. 96, No. B5, 1991, pp. 8295-8303. doi:10.1029/91JB00249

[5] M. van Camp, S. D. P. Williams and O. Francis, “Uncertainty of Absolute Gravity Measurements,” Journal of Geophysical Research, Vol. 110, No. B5, 2005.

[6] A. Lambert, N. Courtier and T. S. James, “Long-Term Monitoring by Absolute Gravimetry: Tides to Postglacial Rebound,” Journal of Geodynamics, Vol. 41, No. 1-3, 2006, pp. 307-317. doi:10.1016/j.jog.2005.08.032

[7] S. Mazzotti, A. Lambert, N. Courtier, L. Nykolaishen and H. Dragert, “Crustal Uplift and Sea Level Rise in Northern Cascadia from GPS, Absolute Gravity, and Tide Gauge Data,” Geophysical Research Letters, Vol. 34, No. 15, 2007, 5 p.

[8] S. D. P. Williams, T. F. Baker and G. Jeffries, “Absolute Gravity Measurements at UK Tide Gauges,” Geophysical Research Letters, Vol. 28, No. 12, 2001, pp. 2317-2320. doi:10.1029/2000GL012438

[9] M. Orlob and A. Braun, “On the Detectability of Synthetic Disturbances in FG5 Absolute Gravimetry Data Using Lomb-Scargle Analysis,” Geomatica, Vol. 66, No. 2, 2012, pp. 113-124. doi:10.5623/cig2012-024

[10] M. Orlob, “Spectral Analysis of Synthetically Affected FG5 Absolute Gravimeter Residuals,” Ph.D. Thesis, Department of Geosciences, The Univsersity of Texas, Dallas, 2011.

[11] K. Charles and R. Hipkin, “Vertical Gradient and Datum Height Corrections to Absolute Gravimeter Data and the Effect of Structured Fringe Residuals,” Metrologia, Vol. 32, No. 3, 1995, p. 193. doi:10.1088/0026-1394/32/3/007

[12] MicroG-Lacoste, “FG5 g8 User’s Manual/Software,” MicroG-Lacoste, Erie, 2008.

[13] T. M. Niebauer, G. S. Sasagawa, J. E. Faller, R. Hilt and F. Klopping, “A New Generation of Absolute Gravimeters,” Metrologia, Vol. 32, No. 3, 1995, pp. 159-180. doi:10.1088/0026-1394/32/3/004

[14] W. Niemeier, “Ausgleichsrechnung,” 1 Edition, Walter de Gruyter, Berlin, 2002.

[15] L. Timmen, R. Roder and M. Schnüll, “Absolute Gravity Determinations with JILAG-3—Improved Data Evaluation and Instrumental Technics,” Bulletin Géodésique, Vol. 67, No. 2, 1993, pp. 71-81. doi:10.1007/BF01371370

[16] G. Blewitt and D. Lavallee, “Effect of Annual Signals on Geodetic Velocity,” Journal of Geophysical Research, Vol. 107, No. B7, 2002, pp. ETG 9-1-ETG 9-11. doi:10.1029/2001JB000570

[17] J. J. Olivero and R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” Journal of Quantitative Spectroscopy and Radiative Transfer, Vol. 17, No. 2, 1977, pp. 233-236. doi:10.1016/0022-4073(77)90161-3

[18] “NIST Handbook of Mathematical Functions,” Cambridge University Press, Cambridge, 2010.

[1] H. Hanada, T. Tsubokawa and S. Tsuruta. “Possible Large Systematic Error Source in Absolute Gravimetry,” Metrologia, Vol. 33, No. 2, 1996, pp. 155-160. doi:10.1088/0026-1394/33/2/4

[2] G. Durando and G. Mana, “Propagation of Error Analysis in a Total Least-Squares Estimator in Absolute Gravimetry,” Measurment Science & Technology, Vol. 13, No. 10, 2002, pp. 1505-1511. doi:10.1088/0957-0233/13/10/301

[3] C. Rothleitner and O. Francis, “On the Influence of the Rotation of a Corner Cube Reflector in Absolute Gravimetry,” Metrologia, Vol. 47, No. 5, 2010, pp. 567-574. doi:10.1088/0026-1394/47/5/007

[4] F. J. Klopping, G. Peter, D. S. Robertson, K. A. Berstis, R. E. Moose and W. E. Carter, “Improvements in Absolute Gravity Oberservations,” Journal of Geophysical Research, Vol. 96, No. B5, 1991, pp. 8295-8303. doi:10.1029/91JB00249

[5] M. van Camp, S. D. P. Williams and O. Francis, “Uncertainty of Absolute Gravity Measurements,” Journal of Geophysical Research, Vol. 110, No. B5, 2005.

[6] A. Lambert, N. Courtier and T. S. James, “Long-Term Monitoring by Absolute Gravimetry: Tides to Postglacial Rebound,” Journal of Geodynamics, Vol. 41, No. 1-3, 2006, pp. 307-317. doi:10.1016/j.jog.2005.08.032

[7] S. Mazzotti, A. Lambert, N. Courtier, L. Nykolaishen and H. Dragert, “Crustal Uplift and Sea Level Rise in Northern Cascadia from GPS, Absolute Gravity, and Tide Gauge Data,” Geophysical Research Letters, Vol. 34, No. 15, 2007, 5 p.

[8] S. D. P. Williams, T. F. Baker and G. Jeffries, “Absolute Gravity Measurements at UK Tide Gauges,” Geophysical Research Letters, Vol. 28, No. 12, 2001, pp. 2317-2320. doi:10.1029/2000GL012438

[9] M. Orlob and A. Braun, “On the Detectability of Synthetic Disturbances in FG5 Absolute Gravimetry Data Using Lomb-Scargle Analysis,” Geomatica, Vol. 66, No. 2, 2012, pp. 113-124. doi:10.5623/cig2012-024

[10] M. Orlob, “Spectral Analysis of Synthetically Affected FG5 Absolute Gravimeter Residuals,” Ph.D. Thesis, Department of Geosciences, The Univsersity of Texas, Dallas, 2011.

[11] K. Charles and R. Hipkin, “Vertical Gradient and Datum Height Corrections to Absolute Gravimeter Data and the Effect of Structured Fringe Residuals,” Metrologia, Vol. 32, No. 3, 1995, p. 193. doi:10.1088/0026-1394/32/3/007

[12] MicroG-Lacoste, “FG5 g8 User’s Manual/Software,” MicroG-Lacoste, Erie, 2008.

[13] T. M. Niebauer, G. S. Sasagawa, J. E. Faller, R. Hilt and F. Klopping, “A New Generation of Absolute Gravimeters,” Metrologia, Vol. 32, No. 3, 1995, pp. 159-180. doi:10.1088/0026-1394/32/3/004

[14] W. Niemeier, “Ausgleichsrechnung,” 1 Edition, Walter de Gruyter, Berlin, 2002.

[15] L. Timmen, R. Roder and M. Schnüll, “Absolute Gravity Determinations with JILAG-3—Improved Data Evaluation and Instrumental Technics,” Bulletin Géodésique, Vol. 67, No. 2, 1993, pp. 71-81. doi:10.1007/BF01371370

[16] G. Blewitt and D. Lavallee, “Effect of Annual Signals on Geodetic Velocity,” Journal of Geophysical Research, Vol. 107, No. B7, 2002, pp. ETG 9-1-ETG 9-11. doi:10.1029/2001JB000570

[17] J. J. Olivero and R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” Journal of Quantitative Spectroscopy and Radiative Transfer, Vol. 17, No. 2, 1977, pp. 233-236. doi:10.1016/0022-4073(77)90161-3

[18] “NIST Handbook of Mathematical Functions,” Cambridge University Press, Cambridge, 2010.