Titan's atmosphere: temperature and dynamics

Abstract

In the lower atmosphere of Titan IR brightness temperatures exhibit meridional contrast ≲3 K. Seasonal variations are absent because of the large radiative time constant. In the upper stratosphere meridional contrasts are ∼20 K, consistent with 100 m s⁻¹ cyclostrophic zonal winds, and the radiative time constant is short, implying a large seasonal variation in the temperature and wind field. The absence of longitudinal thermal structure implies that zonally symmetric flows effect the meridional transport of heat. A simple model yields meridional velocities ∼0.04 cm s⁻¹ and vertical eddy viscosities ∼10³ cm² s⁻¹ in the lower troposphere, and meridional velocities ∼5 cm s⁻¹ in the upper stratosphere.