volume | PIER Journals

Abstract

Remote sensing has been used widely in studying the earth terrain such as snow or sea ice due to its fast, convenient and long-term monitoring capabilities. SAR images acquired could be used to analyze the condition of snow, snow water equivalent (SWE), surface roughness and others. Theoretical models have also been developed to understand how microwave interacts with the snow medium and the scatterers embedded inside the medium. Conventionally, spherical shape of scatterers is commonly used to represent the ice particles embedded inside snow where the actual shape of scatterers can vary. This paper is to present a theoretical model based on radiative transfer formulation that utilizes computational electromagnetics in the modelling of scattering from arbitrary shape of scatterers. The paper also studies the effect of scatterer shape on scattering mechanisms and total backscattering coefficient. Numerical solution of Relaxed Hierarchical Equivalent Source Algorithm (RHESA) was integrated with existing radiative transfer theoretical model to simulate a layer of random discrete snow medium. Several shapes of scatterers were simulated, and theoretical simulation were compared with ground truth measurement data with promising results.

1. Syahali, S. and H. T. Ewe, "Remote sensing backscattering model for sea ice: Theoretical modelling and analysis," Adv. Polar Sci., Vol. 24, No. 4, 248-257, 2013.
doi:10.3724/SP.J.1085.2013.00248

2. Albert, M. D., Y. J. Lee, H. T. Ewe, and H. T. Chuah, "Multilayer model formulation and analysis of radar backscattering from sea ice," Progress In Electromagnetics Research, Vol. 128, 267-290, 2012.
doi:10.2528/PIER12020205

3. Tjuatja, S., A. K. Fung, and J. Bredow, "A scattering model for snow-covered sea ice," IEEE Transactions on Geoscience and Remote Sensing, Vol. 30, 804-810, 1992.
doi:10.1109/36.158876

4. Fung, A. K., Microwave Scattering and Emission Models and Their Applications, Artech House, Norwood, MA, 1994.

5. Ewe, H. T. and H. T. Chuah, "Electromagnetic scattering from an electrically dense vegetation medium," IEEE Transactions on Geoscience and Remote Sensing, Vol. 38, No. 5, 2093-2105, 2000.
doi:10.1109/36.868868

6. Karam, M. A., F. Amar, and A. K. Fung, "Electromagnetic wave scattering from a forest or vegetation canopy: Ongoing research at the University of Texas at Arlington," IEEE Antennas and Propagation Magazine, Vol. 35, No. 2, 18-26, Apr. 1993.
doi:10.1109/74.207648

7. Ao, C. O. and J. A. Kong, "Analytical approximations in multiple scattering of electromagnetic waves by aligned dielectric spheroids," J. Opt. Soc. Am. A, Vol. 19, 1145-1156, Jun. 2002.
doi:10.1364/JOSAA.19.001145

8. Chuah, H.-T., S. Tjuatja, A. K. Fung, and J. W. Bredow, "A phase matrix for a dense discrete random medium: evaluation of volume scattering coefficient," IEEE Transactions on Geoscience and Remote Sensing, Vol. 34, No. 5, 1137-1143, Sep. 1996.
doi:10.1109/36.536529

9. Tsang, L., "Scattering of electromagnetic waves from a half space of nonspherical particles," Radio Science, Vol. 19, No. 6, 1450-1460, Nov.-Dec. 1984.
doi:10.1029/RS019i006p01450

10. Wu, T. D., K. S. Chen, J. Shi, H. W. Lee, and A. K. Fung, "A study of an AIEM model for bistatic scattering from randomly rough surfaces," IEEE Transactions on Geoscience and Remote Sensing, Vol. 46, No. 9, 2584-2598, Sep. 2008.
doi:10.1109/TGRS.2008.919822

11. Gherboudj, I., M. Bernier, F. Hicks, and R. Leconte, "Physical characterization of air inclusions in river ice," Cold Reg. Sci. Technol., Vol. 49, No. 3, 179-194, Sep. 2007.
doi:10.1016/j.coldregions.2007.02.008

12. Gherboudj, I. and M. Bernier, "A backscatter modeling for river Ice: Analysis and numerical results," IEEE Transactions on Geoscience and Remote Sensing, Vol. 48, No. 4, Apr. 2010.
doi:10.1109/TGRS.2009.2034256

13. Du, J., J. Shi, and S. Wu, "A comparison of a second-order snow model with field observations," Proceedings of IGRASS’05, No. 05CH37663C, IEEE, Jul. 25-29, 2005.

14. Tsang, L., K. H. Ding, S. Huang, and X. Xu, "Electromagnetic computation in scattering of electromagnetic waves by random rough surface and dense media in microwave remote sensing of land surfaces," Proceedings of the IEEE, Vol. 101, No. 2, 255-279, Feb. 2013.
doi:10.1109/JPROC.2012.2214011

15. Colbeck, S. C., "A review of sintering in seasonal snow," CRREL Report 97-10, 11, 1997.

16. Gibson, W. C., The Method of Moments in Electromagnetics, Taylor & Francis Group, LLC, 2008.

17. Li, M. K. and W. C. Chew, "Wave-field interaction with complex structures using equivalence principle algorithm," IEEE Transactions on Antennas and Propagation, Vol. 55, No. 1, 130-138, Jan. 2007.
doi:10.1109/TAP.2006.888453

18. Yla-Oijala, P. and M. Taskinen, "Solving electromagnetic scattering by multiple targets with surface equivalence principle algorithm," 2009 3rd European Conference on Antennas and Propagation, 88-92, Berlin, 2009.

19. Fu, X., L. J. Jiang, and H. T. Ewe, "A novel relaxed hierarchical equivalent source algorithm (RHESA) for electromagnetic scattering analysis of dielectric objects," Journal of Electromagnetic Waves and Applications, Vol. 30, No. 12, 1631-1642, 2016.
doi:10.1080/09205071.2016.1210544

20. Lu, C. C. and W. C. Chew, "A multilevel algorithm for solving a boundary integral equation of wave scattering," Micr. Opt. Technol. Lett., Vol. 8, 466-70, 1994.
doi:10.1002/mop.4650071013

21. Taflove, A. and S. C. Hagness, Computational Electrodynamics: The Finite-difference Time-domain Method, 2nd Ed., Artech House, Boston, MA, 2000.

22. Mishchenko, M. I., A. A. Lacis, and L. D. Travis, Scattering, Absorption, and Emission of Light by Small Particles, Cambridge University Press, 2002.

23. Hardy, J., J. Pomeroy, T. Link, D. Marks, D. Cline, K. Elder, and R. Davis, CLPX-Ground: Snow Measurements at the Local Scale Observation Site (LSOS), IOP3, NSIDC DAAC, Boulder, Colorado, USA, 2003.

24. Sarabandi, K., CLPX-Ground: Ground-based L and Ku Band Polarimetric Scatterometry, Version 1, IOP3, NSIDC DAAC, Boulder, Colorado, USA, 2003.

25. Yueh, S. H., CLPX-Airborne: Polarimetric Ku-band Scatterometer (POLSCAT) Data, IOP1 & IOP4, NSIDC DAAC, Boulder, Colorado, USA, 2003.

26. Zhang, L., J. Shi, Z. Zhang, and K. Zhao, "The estimation of dielectric constant of frozen soil-water mixture at microwave bands," Proceedings of 2003 IEEE International Geoscience and Remote Sensing Symposium, Vol. 4, 2903-2905, 2003.

Dr. Chan-Fai Lum

Mr. Xin Fu

Prof. Hong-Tat Ewe

Dr. Li Jun Jiang