Search Publications

Gravity Waves in Titan's Atmosphere: A Comparison Between Linearized Wave Model Calculations and HASI Observations

Cui, Jun; Huang, Jianping; Hao, Yongqiang +3 more

The Huygens Atmospheric Structure Instrument (HASI) detected wavelike temperature fluctuations from 500 to 1,000 km on Titan. However, these fluctuation structures have not been satisfactorily reproduced by any theoretical model to date. In this study, we construct a full-wave model to simulate the observed gravity wave structure. The model includ…

The low electrical conductivity of Titan's lower atmosphere

Lorenz, Ralph D.

Titan's near-surface atmosphere, with a relatively high density and with weak ion production by cosmic rays or other sources, likely has a lower electrical conductivity than the Earth's, possibly <1 fS/m. Direct measurements by the Relaxation Probe on Huygens constrain it to be <0.5 pS/m, and extrapolation from higher altitudes suggests orde…

Evolution of the Huygens Probe Spin During Parachute Descent

Lorenz, Ralph D.; Lebreton, Jean-Pierre; Leroy, Annie +1 more

Schumann resonance on Titan: A critical Re-assessment

Lorenz, Ralph D.; Le Gall, Alice

Extremely Low Frequency (ELF) electric field signals recorded by the Huygens probe have previously been interpreted as indicating a Schumann Resonance (SR) in the ionosphere-ocean cavity. This interpretation required accommodation of a number of anomalous features with respect to the terrestrial SR, namely a lack of observed lightning discharges w…

Remarks about the data processing of the Relaxation Probe on the Huygens experiment

Molina-Cuberos, G. J.; Godard, R.

On January 14, 2005, the Relaxation Probe (RP) on the Huygens experiment measured the electrical conductivity in the lower atmosphere of Titan, the largest Saturnian satellite, from 140 km to 40 km of altitude. The Huygens experiment provided a unique opportunity to compare results from the Mutual Impedance Probe (MIP) with the Relaxation Probe (R…

Aerosols: The key to understanding Titan's lower ionosphere

López-Moreno, J. J.; Molina-Cuberos, G. J.; Witasse, O. +2 more

The Permittivity Wave and Altimetry system on board the Huygens probe observed an ionospheric hidden layer at a much lower altitude than the main ionosphere during its descent through the atmosphere of Titan, the largest satellite of Saturn. Previous studies predicted a similar ionospheric layer. However, neither previous nor post-Huygens theoreti…

The near-surface methane humidity on Titan

Lora, Juan M.; Ádámkovics, Máté

We retrieve vertical and meridional variations of methane mole fraction in Titan's lower troposphere by re-analyzing near-infrared ground-based observations from 17 July 2014 UT (Ádámkovics et al., 2016). We generate synthetic spectra using atmospheric methane profiles that do not contain supersaturation or discontinuities to fit the observations,…

Wind shear and turbulence on Titan: Huygens analysis

Lorenz, Ralph D.

Wind shear measured by Doppler tracking of the Huygens probe is evaluated, and found to be within the range anticipated by pre-flight assessments (namely less than two times the Brunt-Väisälä frequency). The strongest large-scale shear encountered was ∼5 m/s/km, a level associated with 'Light' turbulence in terrestrial aviation. Near-surface winds…

Huygens and Titan's methane cycle

Maltagliati, Luca

Eight-color maps of Titan's surface from spectroscopy with Huygens' DISR

Karkoschka, Erich; Schröder, Stefan E.

During the descent of the Huygens probe in Titan's atmosphere, the Descent Imager/Spectral Radiometer (DISR) acquired spectra of 3660 locations within 250 km of the landing site. Each spectrum consisted of 200 resolution elements between 480 and 960 nm wavelength. With the help of radiative transfer models, contributions from the atmosphere and su…