ORBIT REDUCTION IN INSAR FOR DEFORMATION OBSERVATIONS MOUNT MERAPI
Keywords:
orbital phase, InSAR, deformation, polynomialAbstract
Ground deformation is an important parameter to monitor volcanic activities. It reflects the dynamic processes beneath the surface and should be monitored to understand the volcano status. One technique to monitor ground deformation is Interferometric Synthetic Aperture Radar (InSAR) which works based on radar data that observed whether by airplane or satellite. One important factor in InSAR data processing is orbital effect that appears as a systematic phase in interferogram. The systematic orbital phase can be modelled by mathematical approach especially polynomial equation. This article assesses the utilization of polynomial approach to reduce the orbital phase by using free open source software. As a case study, ALOS-PALSAR data for Merapi Volcano is chosen and it is found that the polynomial function order 2 to 4 is suitable to reduce orbital phase for InSAR estimates after phase unwrapping process.
References
Capcova, I. (2005) Satellite Orbit Errors and Their Influence on Interferograms, Diploma Thesis, Department of Mapping and Cartography Faculty of Civil Engineering Czech Technical University, Prague, 84p.
Chen, C.W. and Zebker, H.A. (2001) Two-dimensional phase unwrapping with use of statistical models for cost functions in nonlinear optimization, Journal of the Optical Society of America A, 18, pp. 338-351.
Gabriel, A. K., Goldstein, R.M. and Zebker, H.A. (1989) Mapping Small Elevation Changes Over Large Areas: Differential Radar Interferometry, Journal of Geophysical Research, 94(B7), pp. 9183- 9191.
Graham, L. C. (1974) Synthetic Interferometer Radar for Topographic Mapping, Proceeding of the IEEE, 62(2), pp. 763-768.
Goldstein, R. M., Zebker, H.A. and Werner, C. L. (1988) Satellite Radar Interferometry: Two-Dimensional Phase Unwrapping, Radio Science, 23(4), pp. 713-720.
Hanssen, R.F. (2001) Radar Interferometry: Data Interpretation and Error Analysis. Kluwer Academic Publishers, Dordrecht, 328 pp.
Massonnet, D., Rossi, M., Carmona, C., Adragna, F., Peltzer, G., Feigl, K. and Rabaute, T. (1993) The Displacement Field of the Landers Earthquake Mapped by Radar Interferometry, Nature, 364(6433), pp. 138-142.
Massonnet, D., Feigl, K., Rossi, M. and Adragna, F. (1994) Radar Interferometric Mapping of Deformation in the Year After the Landers Earthquake, Nature, 369(6477), pp. 227-230.
Raucoules, D., Colesanti, C. and Carnec, C. (2007) Use of SAR Interferometry for Detecting and Assessing Ground Subsidence. Comptes Rendus Geosciences, 339(5): 289-302.
Sandwell, D., R. Mellors, X. Tong, M. Wei, and P. Wessel (2011), Open radar interferometry software for mapping surface deformation, Eos Trans. AGU, 92(28), doi:10.1029/2011EO280002.
Tobita, M., Fujiwara, S., Ozawa, S., Rosen, P.A., Fielding, E.J., Werner, C.L., Murakami, M., Nakagawa, H., Nitta, K., Murakami, M. (1998) Deformation of the 1995 North Sakalin Earthquake Detected by JERS-1/SAR Interferometry. Earth Planet Space, 50, pp. 313-325.
Wessel, P. and Smith, W.H.F. (1991) Free Software Helps Map and Display Data, EOS Trans, AGU, 72, pp.
