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A reevaluation of spectral ratios for Lunar Mare TiO 2 mapping
Author(s) -
Johnson Jeffrey R.,
Larson Stephen M.,
Singer Robert B.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl02094
Subject(s) - analytical chemistry (journal) , contrast ratio , spectral line , wavelength , materials science , optics , mineralogy , titanium , mass ratio , reflectivity , contrast (vision) , content (measure theory) , aspect ratio (aeronautics) , chemistry , physics , astrophysics , mathematics , environmental chemistry , optoelectronics , astronomy , mathematical analysis , metallurgy
The empirical relation established by Charette et al. [1974] between the 400/560 nm spectral ratio of mature mare soils and weight percent TiO 2 has been used extensively to map titanium content in the lunar maria [e.g., Johnson et al., 1977; Johnson et al., 1991b]. Relative reflectance spectra of mare regions show that a reference wavelength further into the near‐IR, e.g., > 700 nm, could be used in place of the 560 nm band to provide greater contrast (a greater range of ratio values) and hence a more sensitive indicator of titanium content. An analysis of 400/730 nm ratio values derived from both laboratory and telescopic relative reflectance spectra suggests that this ratio provides greater sensitivity to TiO 2 content than the 400/560 nm ratio. The increased range of ratio values is manifested in higher contrast 400/730 nm ratio images compared to 400/560 nm ratio images. This potential improvement in sensitivity encourages a reevaluation of the original Charette et al. [1974] relation using the 400/730 nm ratio.