Synthetic aperture radar interferometry(4)

Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. By exploiting the phase of the coherent radar signal, interf

Fig.12.(a)Radar brightness image of Mojave desert near Fort Irwin,CA derived from SIR-C C-band

(5.6-cm wavelength)repeat-track data.The image extends about20km in range and50km in azimuth.

(b)Phase of the interferogram of the area showing intrinsic fringe variability.The spatial baseline of the observations is about70m perpendicular to the line-of-sight direction.(c)Flattened interferometric phase assuming a reference surface at zero elevation above a spherical earth.

baseline makes with respect to a reference horizontal plane.

Then,(10)can be rewritten

as

is the look angle,the angle the line-of-sight vector

makes with respect to nadir,shown in Fig.9.

Fig.12(b)shows an interferogram of the Fort Irwin,CA,

generated using data collected on two consecutive days of the

SIR-C mission.In this figure,the image brightness represents

the radar backscatter and the color represents the interfero-

metric phase,with one cycle of color equal to a phase change

of

be a unit vector pointing to a surface of constant

elevation,,is given

by

(12)

where

(13)

and

(14)

assuming a spherical Earth with

radius

is the local incidence angle relative to a spherical sur-

face,