In situ measurements of the physical characteristics of Titan's environment

Fulchignoni, M.; Ferri, F.; Angrilli, Francesco; Ball, Andrew; Bar‐Nun, A.; Barucci, Maria Antonietta; Bettanini, C.; Bianchini, G.; Borucki, W. J.; Colombatti, Giacomo; Coradini, M.; Coustenis, A.; Debei, S.; Falkner, P.; Fanti, Giulio; Flamini, E.; Gaborit, V.; Grard, R.; Hamelin, Michel; Harri, A. M.; Hathi, B.; Jernej, I.; Leese, M. R.; Lehto, A.; Stoppato, P. F. Lion; López-Moreno, J. J.; Mäkinen, T.; McDonnell, J. A. M.; McKay, Christopher P.; Molina‐Cuberos, G. J.; Neubauer, F. M.; Pirronello, V.; Rodrigo, R.; Saggin, Bortolino; Schwingenschuh, K.; Seiff, A.; Simões, F.; Svedhem, H.; Tokano, Tetsuya; Towner, M. C.; Trautner, R.; Withers, Paul; Zarnecki, J. C.

doi:10.1038/nature04314

Cited by 633 publications

(496 citation statements)

References 42 publications

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“…We use a model with 20 layers, which have boundaries (levels) that are evenly spaced in pressure above and below 300 mbar (hPa), covering the 2.75 -1466.45 mbar range sampled by the Huygens Atmospheric Structure Instrument (HASI) on Cassini (Fulchignoni et al, 2005). This corresponds to an altitude range from the surface up to 147 km.…”

Section: Structure and Compositionmentioning

confidence: 99%

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

Ádámkovics

Mitchell

Hayes

et al. 2016

Icarus

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The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5 µm (H-band) were performed during the same night using instruments with adaptive optics at both the W. M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, R = λ/∆λ ≈ 1, 500, while the Keck observations were performed with NIRSPAO near 1.5525 µm at higher resolution, R ≈ 25, 000. The moderate resolution observations are used for flux calibration and for the determination of model parameters that can be degenerate in the interpretation of high resolution spectra. Line-by-line calculations of CH 4 and CH 3 D correlated k distributions from the HITRAN 2012 database were used, which incorporate revised line assignments near 1.5 µm. We fit the surface albedo and aerosol distributions in the VLT SINFONI observations that cover the entire H-band window and used these quantities to constrain the models of the high-resolution Keck NIRSPAO spectra when retrieving the methane abundances. Cassini VIMS images of the polar regions, acquired on 20 July 2014 UT, are used to validate the assumption that the opacity of tropospheric aerosol is relatively uniform below 10 km. We retrieved methane abundances at latitudes between 42 • S and 80 • N. The tropospheric methane in the Southern mid-latitudes was enhanced by a factor of ∼10-40% over the nominal profile that was measured using the GCMS on Huygens. The Northern hemisphere had ∼90% of the nominal methane abundance up to polar latitudes (80 • N). These measurements suggest that a source of saturated polar air is equilibrating with dryer conditions at lower latitudes.

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Section: Structure and Compositionmentioning

confidence: 99%

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

Ádámkovics

Mitchell

Hayes

et al. 2016

Icarus

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“…42). In the statistically steady state of the GCM, this formulation of radiative transfer results in a realistic temperature profile with a tropopause, without the need to invoke discrete haze layers or cloud decks; in the lower troposphere, temperatures are within l K and near the tropopause within ∼5 K of those measured by the Huygens probe 43 (Supplementary Fig. 2).…”

mentioning

confidence: 99%

Polar methane accumulation and rainstorms on Titan from simulations of the methane cycle

Schneider

Graves

Schaller³

et al. 2012

Nature

119

124

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Supplementary InformationOur GCM is based on the Flexible Modeling System of the Geophysical Fluid Dynamics Laboratory (http://fms.gfdl.noaa.gov). It is similar to standard models for Earth's atmosphere, but with Titan's radius, planetary rotation rate, material properties, and seasonally varying insolation, and with a methane cycle instead of a water cycle. The GCM has similarities to the models in refs. 16, 17, but unlike those, it is 3D and eddy-resolving and has a different representation of radiative transfer and surface processes.Resolution. The GCM solves the hydrostatic primitive equations in vorticity-divergence form, using the spectral transform method in the horizontal and finite differences in the vertical 31 . The horizontal spectral resolution is T21 (corresponding to about 5 • × 5 • resolution of the transform grid). The vertical coordinate is σ = p/p s (pressure p normalized by surface pressure p s ); it is discretized with 18 unequally spaced levels 32 . The top of the model is at σ = 0; the uppermost full level has a mean pressure of 15 mbar (altitude ∼90 km). The time-stepping scheme is a semiimplicit leapfrog scheme (timestep 1600 s).

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“…One of multiple missions of Huygens probe is to detect if there are electric discharges in Titan's atmosphere and to explore the electromagnetic properties of Titan's lower ionosphere during its descent [Grard et al, 1995;Fulchignoni et al, 2005]. If SR were detected on Titan, they would provide a good support for the existence of the electrical discharges in the lower atmosphere on Titan, and the SR parameters are also useful in the study of the electromagnetic properties of Titan's lower ionosphere.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

2006

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[1] The conducting ionosphere and conducting surface of Titan, Venus, and Mars form a concentric resonator, which would support the possibility of the existence of global electromagnetic resonances. On Earth, such resonances are commonly referred to as Schumann resonances and are excited by lightning discharges. The detection of such resonances on other planets would give a support for the existence of the electrical discharges in the lower atmosphere on these planets. In this paper, a three-dimensional finite difference time domain modeling for the extremely low frequency propagation is employed to study the Schumann resonance problems on Titan, Venus, and Mars. The atmospheric conductivity profiles for these studies are derived from the previously reported ionospheric models for these planets. The Schumann resonance frequencies and Q factors on these planets are calculated and are critically compared with those obtained from the previously published models.

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In situ measurements of the physical characteristics of Titan's environment

Cited by 633 publications

References 42 publications

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

Polar methane accumulation and rainstorms on Titan from simulations of the methane cycle

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

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