Fig. 39. 1.04\dmic\ and 1.55\dmic\ Water Ice Absorption Band Depths for
a Variety of Ice Reflectance Spectra.
The circ' symbols represent laboratory spectra from Clark (1980), Table
I. FF, MFF, MCF, and CF are his fine, medium-fine, medium-coarse, and coarse
grained frosts, and FOI e, f, and g are three different frost-on-ice samples.
`$\bullet$' symbols are solar system spectra from Clark et al (1984),
Table II, showing the leading and trailing hemispheres of Europa, Ganymede,
Callisto, and Rhea, and also Saturn's rings, with the obvious abbreviations.
Finally, the squares show the band depths for a possible segregated icy
component in the Callisto leading hemisphere spectrum, assuming the non-ice
component is spectrally bland between 1.0 and 2.5\mic\ and has a reflectance
of 0.15. The symbol labels show the assumed fractional coverage of the
ice component in each case. 1\dmic\ albedos for the ice component assuming
10 %, 20 %, and 30 % areal coverage are 0.95, 0.55, and 0.42 respectively.
Note the large range of possible band depths and band ratios for the laboratory
ices (especially the frost-on-ice samples), and the closeness of the band
depths of the 20 % areal coverage ice component on Callisto to those of
the trailing hemisphere of Ganymede both here and on Fig.
40
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