[Previous] | [Session 45] | [Next]

[45.25] Geographic control of Titan's mid-latitude clouds

H.G. Roe, M.E. Brown, E.L. Schaller, A.H. Bouchez (Caltech), C.A. Trujillo (Gemini Observatory)

Observations of tropospheric clouds (1-6) and the recent Huygens images of channels show that Titan has an active methane hydrological cycle. Titan's south polar clouds are now well known (3-5) and thought to be driven by small seasonal variations in surface temperature (3). The recent discovery (6) and continued observations (7) of significant cloud activity at 40^\circS latitude led to the suggestion that these mid-latitude clouds are the result of either seasonally evolving global circulation or surface geography (6). We report here further observations of Titan that clearly link the formation of the mid-latitude clouds to a region of Titan's surface centered at ~350^\circW longitude, ~40^\circS latitude. Analysis of the complete dataset does not support the earlier suggestion (6) that these clouds are a new phenomenon related to seasonal change. The strong link between geographic location and cloud formation along with the lack of evidence for seasonal change in the mid-latitude clouds leads to the conclusion that a geological mechanism is responsible for the formation of these clouds. We propose that geysers or cryovolcanism are sporadically active near ~350^\circW longitude, ~40^\circS latitude. The implied rate of volatile release would easily supply enough methane to balance the loss to photolytic chemistry in the upper atmosphere.

1.~Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., Nature 395, 575-578 (1998). 2.~Griffith, C.A., Hall, J.L., Geballe, T.R., Science 290, 509-513 (2000). 3.~Brown, M.E., Bouchez, A.H., Griffith, C.A., Nature 420, 795-797 (2002). 4.~Roe, H.G., de Pater, I., Macintosh, B.A., McKay, C.P., ApJ 581, 1399-1406 (2002). 5.~Bouchez, A.H., Brown, M.E., ApJ 618, L53-L56 (2005). 6.~Roe, H.G., Bouchez, A.H., Trujillo, C.A., Schaller, E.L., Brown, M.E., ApJ 618, L49-L52 (2005). 7.~Porco, C.C., et al., Nature 434, 159-168 (2005).

HGR is supported by an NSF Astronomy & Astrophysics Postdoctoral Fellowship (NSF AST-0401559). ELS is supported by an NSF Graduate Research Fellowship. Additional support was provided by an NSF grant to MEB (NSF AST-0307929).

The author(s) of this abstract have provided an email address for comments about the abstract: hroe@gps.caltech.edu

[Previous] | [Session 45] | [Next]

Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.