Europa, Ganymede, Callisto 
S. OSTRO ET AL., 
JGR PLANETS, 1992. 
Figure 2. Average values of the (A) OC radar reflectivity cr^ L , (B) circular polarization ratio 
Prr/vrli an d (C) linear polarization ratio p l — f° r the Greenland percolation fa 
cies obtained by averaging the radar measurements recorded by AIRSAR at Crawford Point along 
the flight path, at 5.6 (C-), 24 (L-), and 68 cm wavelength (P-), as a function of the incidence 
angle of the radar illumination. Radar backscatter values and polarization ratios measured from 
wavelength-sized roughness on a surface of lava (black squares) (J. J. van Zyl, C. F. Burnette, and 
T. G. Farr, Geophys. Res. Lett. 18, 1787 (1991)) and from tropical rain forest (black dots) (A. 
Freeman, S. Durden, and R. Zimmerman, Proc. of the Int. Geos. Rem. Sens. Symp., Houston, 
Texas, May 26-29, IEEE New York Pub., 1686 (1992)) are also shown in the Figure. The values 
indicated for the icy satellites Europa (E), Ganymede (G), and Callisto (C) are disk-integrated 
average measurements at 3.5 and 13 cm wavelengths [5].