Bibcode
Sicardy, B.; Colas, F.; Widemann, T.; Bellucci, A.; Beisker, W.; Kretlow, M.; Ferri, F.; Lacour, S.; Lecacheux, J.; Lellouch, E.; Pau, S.; Renner, S.; Roques, F.; Fienga, A.; Etienne, C.; Martinez, C.; Glass, I. S.; Baba, D.; Nagayama, T.; Nagata, T.; Itting-Enke, S.; Bath, K.-L.; Bode, H.-J.; Bode, F.; Lüdemann, H.; Lüdemann, J.; Neubauer, D.; Tegtmeier, A.; Tegtmeier, C.; Thomé, B.; Hund, F.; deWitt, C.; Fraser, B.; Jansen, A.; Jones, T.; Schoenau, P.; Turk, C.; Meintjies, P.; Hernandez, M.; Fiel, D.; Frappa, E.; Peyrot, A.; Teng, J. P.; Vignand, M.; Hesler, G.; Payet, T.; Howell, R. R.; Kidger, M.; Ortiz, J. L.; Naranjo, O.; Rosenzweig, P.; Rapaport, M.
Referencia bibliográfica
Journal of Geophysical Research, Volume 111, Issue E11, CiteID E11S91
Fecha de publicación:
11
2006
Número de citas
51
Número de citas referidas
50
Descripción
We report the observation of two stellar occultations by Titan on 14
November 2003, using stations in the Indian Ocean, southern Africa,
Spain, and northern and southern Americas. These occultations probed
altitudes between ~550 and 250 km (~1 to 250 μbar) in Titan's upper
stratosphere. The light curves reveal a sharp inversion layer near 515
+/- 6 km altitude (1.5 μbar pressure level), where the temperature
increases by 15 K in only 6 km. This layer is close to an inversion
layer observed fourteen months later by the Huygens HASI instrument
during the entry of the probe in Titan's atmosphere on 14 January 2005
[Fulchignoni et al., 2005]. Central flashes observed during the first
occultation provide constraints on the zonal wind regime at 250 km, with
a strong northern jet (~200 m s-1) around the latitude
55°N, wind velocities of ~150 m s-1 near the equator, and
progressively weaker winds as more southern latitudes are probed. The
haze distribution around Titan's limb at 250 km altitude is close to
that predicted by the Global Circulation Model of Rannou et al. (2004)
in the southern hemisphere, but a clearing north of 40°N is
necessary to explain our data. This contrasts with Rannou et al.'s
(2004) model, which predicts a very thick polar hood over Titan's
northern polar regions. Simultaneous observations of the flashes at
various wavelengths provide a dependence of τ $propto$
λ-q, with q = 1.8 +/- 0.5 between 0.51 and 2.2 μm
for the tangential optical depth of the hazes at 250 km altitude.