Roughness Model of Radar Backscattering From Bare Soil Surfaces Amimul Ehsan Electrical Engineering and Computer Science Department, University of Kansas April 29, 2015

2 Outlines  Motivation and Objective  Introduction  Surface Roughness  Backscattering Roughness Model  Results and Discussions  Reference

Motivation and Objective 3  Radar Backscattering is affected by three target features namely surface roughness, vegetation and soil moisture. To get the effect of any particular feature, other two need to be subtracted from the measured backscattering.  The main goal of this study is to determine the dependence of radar backscatter on roughness parameter.  Three models namely Physical Optics Model, Geometric Optics Model and Small perturbation Model are studied for backscattering.

Introduction 4  When microwave EM energy transmitted by a RADAR system reaches the earth surface, some is absorbed by the surface and the remainder is reflected in multiple directions.  These surface reflections are referred to as scattering of microwave EM energy.  The microwave EM energy that is scattered in the Radar’s direction of transmission is the only EM energy that is detected by the radar – this EM energy is referred to as microwave or radar backscatter Fig. Schematic view of scattering geometry [3]

Surface Roughness 5  Rough surface corresponds to Gaussian distribution. where, the scattered intensity with roughness parameter, Fig. Schematic of types of surface roughness [3]

Physical Optics Model 6  This model predicts the incoherent backscattering coefficient for a given surface. Conditions under this model applicable,

Geometric Optics Model 7  This model has the form, Conditions of this model,

Small Perturbation Model 8  This model has the form, Surface roughness that has a Gaussian correlation function, This model can be used for,

Roughness Effect on Backscattering 9  Physical Optics and Geometric Optics Model Fig. Backscattering of Physical Optics Model by varying the roughness parameter Fig. Backscattering of Geometric Optics Model by varying the roughness parameter

Roughness Effect on Backscattering 10  Small Perturbation Model Fig. Backscattering of Small Perturbation Model by varying the roughness parameter

References 11 [1] Engman, Edwin T.; Wang, J.R., "Evaluating Roughness Models of Radar Backscatter," IEEE Transactions on Geoscience and Remote Sensing, vol.GE-25, no.6, pp.709,713, Nov [2] Yisok Oh; Sarabandi, K.; Ulaby, F.T., "An empirical model and an inversion technique for radar scattering from bare soil surfaces," IEEE Transactions on Geoscience and Remote Sensing, vol.30, no.2, pp.370,381, Mar 1992 [3] Tsan Mo, Thomas J. Schmugge, Thomas J. Jackson, “Calculations of radar backscattering coefficient of vegetation-covered soils,” Remote Sensing of Environment, Volume 15, Issue 2, March 1984, Pages [4] F. T. Ulaby, R. K. Moore, and A. K. Fung, 1986, Microwave Remote Sensing Active and Passive. Dedham, MA: Artech House, 1986, vol. 3. [5] Zribi, M.; Gorrab, A.; Baghdadi, N., "A new soil roughness parameter for the modelling of radar backscattering over bare soil," Geoscience and Remote Sensing Symposium (IGARSS), 2014 IEEE International, vol., no., pp.3378,3381, July [6] Choudhury, B. J., T. J. Schmugge, A. Chang, and R. W. Newton (1979), Effect of surface roughness on the microwave emission from soils, J. Geophys. Res., 84(C9), 5699–5706, [7] D.L. Evans, T.G. Farr and J. J. van Zyl, "Estimates of surface roughness derived from synthetic aperture radar (SAR) data, " IEEE Transactions on Geoscience and Remote Sensing, vol. 30, pp , 1992.