Using Specular Reflections to Resolve the Degeneracy between Surface and Atmospheric Absorptions
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Transcript of Using Specular Reflections to Resolve the Degeneracy between Surface and Atmospheric Absorptions
Using Specular Reflections to Resolve the Degeneracy between Surface and Atmospheric Absorptions
Jason W. Barnes
University of Idaho
Department of Physics
Cassini Titan Surface Working Meeting
2013 January 30
Tucson, Arizona
A Terrestrial Analog:Beijing, China
T85 CM_1721848119 5-micron coadd (16 channels)
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119(saturated)
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
T85 CM_1721848119
Kivu Lacus
Sand Mountain, Nevada
Sidewalk, University of Idaho, Moscow, Idaho
Sidewalk, University of Idaho, Moscow, Idaho
H2O ice can not be present inabundance: the 2-micron and2.7-micron spectral shapesare incompatible with Titan'sspectrum.
Models from Caitlin Griffith
The gap between observed VIMS I/F and atmospheric models show that Titan’s surface reflectance is decreasing from
~2.0 to ~2.15 microns
Titan shows interesting spectral diversity in the 5-micronwindow. From Clark et al., (2010a).
Conclusions:
• T85 specular reflection visible at 5um, but also at at 2.8, 2.7, and 2.0um! Not at 1.6 or below.
• I used the intensity of the specular reflection as a function of wavelength to infer Titan’s atmospheric transmission at the north pole. Eventually, goal would be to use this to deconvolve surface & atmosphere
• So far, optical depth T is about 0.45 higher at 2.7 relative to 2.8 – implies that uncorrected I/F 2.8/2.7um ratios do not constrain surface directly
• Can then use this to correct out spectra within each window to reveal slopes, spectral shapes, constraining composition