A Study of Dense Medium Scattering and Its Applications in Sea Ice Research in Ross Island, Antarctica

1
A Study of Dense Medium Scattering and Its
Applications in Sea Ice Research in Ross Island,
Antarctica

• Y. J. Lee1, W. K. Lim2, H. T. Ewe1 and H. T.
  Chuah1
• 1Universiti Tunku Abdul Rahman
• 2Multimedia University

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Contents

• Introduction
• Development and Application of the Dense Medium
  Phase and Amplitude Correction Theory (DM-PACT)
• Modeling of the Sea Ice and Ice Shelf
• Development of Inverse Scattering Models for Sea
  Ice Thickness Retrieval
• Conclusion

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Introduction

• Development of remote sensing technology
  satellites and synthetic aperture radar (SAR).
• Increase in use of remote sensing devices for
  data retrieval.
• Many applications evolving with the technology.
• Need for proper forward and inverse scattering
  models for such applications.

K.M. Golden, M. Cheney, K.H. Ding, A.K. Fung,
T.C. Grenfell, D. Isaacson, J.A. Kong, S.V.
Nghiem, J. Sylvester, and D.P. Winebrenner,
Forward electromagnetic scattering models for
sea ice, IEEE Transactions on Geoscience and
Remote Sensing, Vol. 36, No. 5, pp. 16551674,
1998
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Development of the DM-PACT

• Many forward models were developed.
• Several models utilized the Radiative Transfer
  Theory (RTT), which can be written in the form
  (Chandrasekhar 1960)
• I, e, P, dO and z are the Stokes vector,
  extinction matrix, phase matrix of the medium,
  solid angle and vertical direction respectively.

Chandrasekhar, S., Radiative Transfer. New York
Dover, 1960
5

• Early modeling assumes a homogeneous medium
  scatterers in far field from one another.
• Only applies when
• Scatterers are small.
• Average spacing larger than ?/3.
• Solution Improvements were made to the phase
  matrix, P, in 1 using the Antenna Array Theory.

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• The improved phase matrix, P has the following
  expression
• is the dense medium phase correction
  factor (Chuah et al. 1996) and S is the Stokes
  matrix for Mie scatterers with the Close Spacing
  Amplitude Correction (Fung and Eom 1985).

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, pp. 11371143,
1996 A.K. Fung, and H.J. Eom, A study of
backscattering and emission from closely packed
inhomogeneous media, IEEE Trans. Geoscience
Remote Sensing, Vol. 23, No. 5, pp. 761767, 1985
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• takes into account the close spacing
  effect of scattering among the scatterers.
• S relates the scattered intensities to the
  incident intensities of the scatterer.

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• From equation 2, can further be
  expressed as the following
• where
• d is the average distance between scatterers
• k is the propagation vector
• l is the correlation length

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• The improved phase matrix Dense Medium Phase
  and Amplitude Correction Theory (DM-PACT).
• An analysis using the DM-PACT based on iterative
  solution on electrically dense medium was done
  (Ewe et al.).

S. Tjuatja, A.K. Fung, and J. Bredow, A
scattering model for snow-covered sea ice, IEEE
Trans. Geoscience Remote Sensing, Vol. 30, No.
4, pp. 804810, 1992 H.T. Ewe, and H.T. Chuah,
An analysis of the scattering of discrete
scatterers in an electrically dense medium, 1998
IEEE International Geoscience and Remote Sensing
Symposium Proceedings (IGARSS'98), Vol. 5, pp.
23782380, 1998 H.T.Ewe, and H.T. Chuah, A Study
of Dense Medium Effect Using A Simple
Backscattering model, 1997 IEEE International
Geoscience and Remote Sensing Symposium
Proceedings (IGARSS'97) Remote Sensing - A
Scientific Vision for Sustainable Development,
Vol. 3, pp. 14271429, 1997
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Application of the DM-PACT

• A backscattering model was developed (Ewe et al.)
  for inhomogeneous media.
• Model incorporates
• Iterative solution for RTT
• DM-PACT
• IEM Model to characterize rough surface

H.T. Ewe, M.E. Veysoglu, C.C. Hsu, R.T. Shin, and
J.A. Kong, Radiative Transfer Theory for Remote
Sensing of Sea Ice, 1994 IEEE International
Geoscience and Remote Sensing Symposium
Proceedings (IGARSS'94) Surface and Atmospheric
Remote Sensing Technologies, Data Analysis an
Interpretation, Vol. 1, pp. 623625, 1994 H.T.
Ewe, H.T. Chuah, and A.K. Fung, A backscatter
model for a dense discrete medium Analysis and
numerical results, Remote Sensing of
Environment, Vol. 65, No. 2, pp. 195203,
1998 Fung, A.K., Microwave Scattering and
Emission Models and Their Applications, Norwood,
MA Artech House, 1994 C.Y. Hsieh, and A.K. Fung,
Application of an Extended IEM to Multiple
Surface Scattering and Backscatter Enhancement,
Journal of Electromagnetic Waves and
Applications, Vol. 13, No. 1, pp. 121136,
1999 A.K. Fung, W.Y. Liu, K.S. Chen, and M.K.
Tsay, An Improved IEM Model for Bistatic
Scattering from Rough Surface, Journal of
Electromagnetic Waves and Applications, Vol. 16,
No. 5, pp. 689702, 2002
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Modeling of the Sea Ice and Ice Shelf

• The backscattering model developed by Ewe et al.
  was applied to sea ice and ice shelf.
• Ground truth measurement was conducted at Ross
  Island, Antarctica to verify the model.
• Satellite images were also acquired as part of
  the study.

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• Backscattering model was initially tested for
  single layer sea ice.
• Model configuration

M.D. Albert, T.E. Tan, H.T. Ewe, and H.T. Chuah,
A theoretical and measurement study of sea ice
and ice shelf in Antarctica as electrically dense
media, Journal of Electromagnetic Waves and
Applications, Vol. 19, No. 14, pp. 19731981,
2005
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• Simulation results

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• A multilayer model was developed to take into
  account the snow cover on the sea ice (Mohan et
  al.).
• Extension of the backscatter model by Ewe et al.
• Results show good matching between the multilayer
  model, Matrix Doubling method and CEAREX
  measurements.

Y.J. Lee, H.J. Yap, M.D. Albert, H.T. Ewe, and
H.T. Chuah, Multiyear Field Measurement and
Sensitivity Study of Radar Returns in Scott Base,
Antarctica, Proceedings for the 3rd Malaysian
International Seminar on Antarctica (MISA3) From
the Tropics to the Poles, Sabah, Malaysia, pp.
2128, July 2007 M.D., Albert, H.T. Ewe, and H.T.
Chuah, Understanding the Scattering Mechanism in
Sea Ice and Its Relation to Remote Sensing,
Joint Scientific Committee on Antarctic Research
(SCAR)-International Arctic Science Committee
(IASC) Open Science Conference, St Petersburg,
Russia, 811 July 2008
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• Model configuration

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Development of Inverse Scattering Models for Sea
Ice Thickness Retrieval

• Many inverse models were developed to retrieve
  sea ice thickness.
• Based on existing models, new models utilizing
  the RT and DM-PACT were later developed.

Golden, K.M., D. Borup, M. Cheney, E. Cherkaeva,
M.S. Dawson, K.H. Ding, A.K. Fung, D. Isaacson,
S.A. Johnson, A.K. Jordan, J.A. Kong, R. Kwok,
S.V. Nghiem, R.G. Onstott, J. Sylvester, D.P.
Winebrenner, and I.H.H. Zabel, Inverse
electromagnetic scattering models for sea ice,
IEEE Transactions on Geoscience and Remote
Sensing, Vol. 36, No. 5, 16751704, 1998
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• For active remote sensing
• Radiative Transfer Inverse Scattering Model
  (RTISM)
• For passive remote sensing
• Neural Network with RT-DMPACT
• Genetic Algorithm with RT-DMPACT

Y.J. Lee, W.K. Lim, and H.T. Ewe, A Study Of An
Inversion Model For Sea Ice Thickness Retrieval
In Ross Island, Antarctica, Progress in
Electromagnetics Research (PIER), Vol. 111, pp.
381406, 2011 H.J. Yap, W.K. Lim, H.T. Ewe and
H.T. Chuah, Passive Microwave Remote Sensing for
Sea Ice Thickness Retrieval Using Neural Network
and Genetic Algorithm, Proceedings in Progress
In Electromagnetics Research Symposium (PIERS),
Beijing, China, pp. 12291233, 2327 March
2009 H.J. Yap, W.K. Lim, H.T. Ewe and H.T. Chuah,
Neural Network and Genetic Algorithm Inversion
for Sea Ice Thickness using Passive Microwave
Remote Sensing, 4th Malaysian International
Seminar on Antarctica (MISA4) Legacy of IPY to
the Tropics, Petaling Jaya, Malaysia. Poster
presented. 13 April 2009
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- Radiative Transfer Inverse Scattering Model
(RTISM)

• Flowchart for the Radiative Transfer Inverse
  Scattering Model (RTISM)

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• Sea ice thickness retrieval using the Radiative
  Transfer Inverse Scattering Model (RTISM)

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- Neural Network with RT-DMPACT- Genetic
Algorithm with RT-DMPACT

• Flowchart for the Neural Network with RT-DMPACT

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• Flowchart for the Genetic Algorithm with
  RT-DMPACT

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• Sea ice thickness retrieval

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Conclusion

• Improvements to the phase matrix of the Radiative
  Transfer equation was done.
• The technique, named the DM-PACT is able to
  better model the inhomogeneous media.
• A backscattering model was later developed based
  on RT and DM-PACT.
• Application of the study towards the remote
  sensing of sea ice was done.
• The backscattering model was extended to a
  multilayer model.
• Inverse models were later developed based on the
  backscattering model to retrieve sea ice
  thickness.

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Proof of Global Warming
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• Thank you for your attention.