INVERSION OF SYNTHETIC APERTUR,E R,ADAR (SAR) - MSpace ...

elorv that sulface. In genetal, sulface scatteling at tetlairl ot ocean sulface
is, horvever, by far dominant relative to volume scattering in geological or'
oceanographic application of SAR.
The palameter o'(r) represents the cotnplex latio of the backscattelecl
wavefielcl to the incident rvavefielcl at the surface boutlclary, ancl indicates a
phase change as well as an amplitude ratio at the scattering surface. The
cornplex backscattering coefÊcient o'(r) may have geophysical signiflcance'
Telrain slope (or incident angle), sur{ace toughress, and complex dielectric
colstant charactelize pt'opelties of a scattelilg surface. Consequently, tliey
ale influeuces on raclal leturtl. The arnplitucle of the cornplex backscatteling
coefficient is goveruecl mainly by tertain slope alcl surface louglÌness.
The complex clielectric cotlstant cletertnines penetlatiotl of microwave, ancl is
closely relatecl to the phase of the cornplex backscattering coefficielt.
In fact, the above two approxitnatiols in Eqs.(4.20) and (4.21) imply that
souLces of the backscattered wavefleld other thal the tnost significaut terrn,
the inciclent wavefield, are neglected. That is exactly the sane idea as Boln
(fir'st) apploxirnatiol ir Eq.(a.9)'
Substituting Eqs.(4.20), and (4.21) into (4.18), we have
U5(ro, r'o;c.,) - ,
I l"ai(r)G¡(r, ro;ø ) frGoQ,r";r),t',
(4.22)
if the incident rvavefield U7 is leplaced by Green's function G6(r, rq;ø). For
the Green's functiou in Eq.(4.i9), we have an approxirnation to a leading
order term in ø given by
Us(ro,ro;co) -
zu îî
8""" J J"
,;,),.,121.
4,@Ta',+o( ^) U2r)
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