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