[X] My Assistant

[volcanopele]

I hate to say this, try IE. Seems to work better there.

Just an advertisement for the talk I provided the most work for, Zibi Turtle's talk at 9:30am in the Titan Lower atmosphere session. I doubt you will be disappointed.

EDIT: That should be 11:30am EDT

Reason for edit: time wrong

[ngunn]

The whole session was great. But with all that methane being convected and precipitated, large lakes with steep shorelines, extensive liquid-carved channels - why hasn't the VIMS team found anything deeper than a puddle?

[Juramike]

The whole session was great. But with all that methane being convected and precipitated, large lakes with steep shorelines, extensive liquid-carved channels - why hasn't the VIMS team found anything deeper than a puddle?

I wasn't exactly sure of the argument of calling the areas "playas" in one of the presentations. I think most of the absorbance curves for depth calculation were generated assuming the bottom albedo was "1.0" (perfect mirror). I kinda think that is highly unlikely.

In a later talk, Lawrence Soderblom's presentation seemed to imply that the 5 micron (2000 cm-1) albedo of Ontario Lacus was nearly zero (no scattering at all, no reflectance). The strong absorbance of ethane at 5 micron means that very little would be required to zero out the spectrum. (Slide 239)

So I think it was the 2.0 micron absorbance (or lack thereof) that was used to imply a shallow lake depth, since reflectance is pretty much unaltered at this wavelenght. (Slide 246).

But this assumes that the surrounding terrain (non-lake) is at the bottom of the lake. (The lake has minimal effect on the 2.0 micron absorbance, thus it's not real deep). If the lake material contains "stuff" (suspended? lying near the bottom?) that reflects 2.0 micron radiation pretty well then the depth analysis doesn't hold water (!).

[2.0 micron is a water absorbance band local minimum, so all it would take to get better reflectance than adjacent non-lake terrain would be some "less water-ice"-like material. So any organic "non-water-ice coated sediment" could do the trick.]

The questions at the end of the presentation did ask about suspended or floating sediment or materials. "You can't judge the depth of Cayuga (a very deep lake in the Finger Lakes region) by what I can see at the surface."

I think a fair statement is that the hydrocarbon absorbance (derived optical depth) from lake reflection is minimal. Not sure whether this could be solely due to shallow liquid depth.


[I also noted that the 5.01 reflectance image shown in Slide 245 correlated nicely with the putative Deep Black unit (which was proposed from the possibly artifact-ridden 2.8/2.7 ratio). "Noise shouldn't correlate" ]

-Mike

-Mike