Gravity waves in Titan's lower stratosphere from Huygens probe in situ temperature measurements

Abstract

The Huygens probe recorded atmospheric temperatures during its parachute descent through the atmosphere of Titan. A careful analysis of these data reveals for the first time spectacular but hitherto-unreported small-scale variations in stratospheric temperatures that we interpret as gravity waves, consistent with detection of such waves at higher altitudes by other means. The structures have a vertical wavelength of 3-8 km and a peak-peak amplitude of ∼2 K that is roughly constant over altitudes from ∼140 km, where measurements began, to ∼60 km. This altitude, below which no significant temperature waves are seen, coincides with a local maximum in the zonal wind profile, and is close to where the Brunt-Väisälä frequency is highest. It seems possible that the zonal wind field influences the vertical gravity wave propagation.