HR: 11:20h
AN: P42A-05    [Abstracts]
TI: Modelling Surface Temperatures on Titan by a General Circulation Model: Constraints on the Surface Type
AU: * Tokano, T
EM: tokano@geo.uni-koeln.de
AF: Institut f\"ur Geophysik und Meteorologie, Universit\"at zu K\"oln, Albertus-Magnus-Platz, K\"oln, 50923 Germany
AB: This study investigates the seasonal and spatial variation of the surface temperature and air temperature in the lower troposphere by a 3-dimensional general circulation model for different putative surface types (porous icy regolith, rock-ice mixture, hydrocarbon lakes) in an effort toconstrain the likely surface type and to understand the meteorology near the surface. For any viable surface type the surface temperature is unlikely to be constant through the year and should more or less vary seasonally and even diurnally, most likely by a few K. Unless the surface is liquid the lower troposphere gets convective near the summer pole where patchy tropospheric clouds have recently been observed. The predicted surface temperature is consistent with Voyager 1 data as long as the thermal inertia of the surface is relativelysmall and/or the surface albedo is low, while a dominance of water ice (high thermal inertia and high albedo) at the surface is unfavourable to reproduce the observation. The lake surface undergoes a larger seasonal variation than the solid surface because of the low albedo and low surface drag. During the Cassini mission the surface temperature ought to be asymmetric about the equator for any surface type, with a warmer south, unless there is a strong accumulation of haze near both poles.The air temperature in the lower troposphere exhibits a smaller latitudinal gradient than the surface and a pole-to-pole gradient due to the presence of a pole-to-pole Hadley circulation, indicating that the temperature within the planetary boundary layer may exhibit a vertical profile characteristic of season, location and scenario. There may be a shallow near-surface inversion layer in cold seasons and a shallow convective layer in warm seasons.
DE: 5409 Atmospheres--structure and dynamics
DE: 5445 Meteorology (3346)
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting