The floatability of aerosols and wave damping on Titan’s seas


Titan, the enigmatic large moon of Saturn, is unique because it is the only satellite of the solar system that is surrounded by a dense atmosphere. Thick layers of photochemical organic aerosols shroud the surface and sediment to the ground. In polar regions, large lakes and seas of liquid hydrocarbons were discovered by the Cassini–Huygens mission. Aerosols that sediment above the lakes run into a liquid surface in which new interactions can take place. In this paper, we address the question of the first contact between the aerosols and the lakes: do the aerosol particles float or rapidly sink into the lakes? We investigated the possible effects of a floating film or slick formed by this organic material and other products of the atmosphere. We also compared the wave damping effect on Earth's oceans to the Titan counterparts. According to this work, Titan appears to be a much more favourable place for such a damping. By inhibiting the formation of the first ripples, this phenomenon could impede the existence of waves at wavelengths larger than a few centimetres. This effect could explain the remarkable smoothness of the sea surface often noticed in Cassini observations.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: A monomer (symbolized by a shaded disk) in contact with a liquid, which is represented in blue.
Fig. 2: Comparison of the wave damping efficiency due to a floating film in the Titan context and under Earth conditions.
Fig. 3: The relative damping ratio y as a function of the wavelength λ in the case of a thin finite thickness film deposited at the surface of water, that is, in the context of Earth.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Code availability

The codes used to generate the plots in this paper are available from the corresponding author upon reasonable request.


  1. 1.

    Hörst, S. M. Titan’s atmosphere and climate. J. Geophys. Res. 122, 432–482 (2017).

    Article  Google Scholar 

  2. 2.

    Stofan, E. R. et al. The lakes of Titan. Nature 445, 61–64 (2007).

    Article  Google Scholar 

  3. 3.

    Lunine, J. I. in Symposium on Titan ESA Special Publication 388 (ed. Kaldeich, B.) 233–239 (European Space Agency, 1992).

  4. 4.

    Alpers, W. & Hühnerfuss, H. The damping of ocean waves by surface films: a new look at an old problem. J. Geophys. Res. 94, 6251–6265 (1989).

    Article  Google Scholar 

  5. 5.

    Lancelot, C. & Mathot, S. Dynamics of a Phaeocystis-dominated spring bloom in Belgian coastal waters. I. Phytoplanktonic activities and related parameters. Mar. Ecol. Prog. Ser. 37, 239–248 (1987).

    Article  Google Scholar 

  6. 6.

    Lin, I. I., Alpers, W. & Liu, W. T. First evidence for the detection of natural surface films by the QuickSCAT scatterometer. Geophys. Res. Lett. 30, 1713 (2003).

    Google Scholar 

  7. 7.

    Wye, L. C., Zebker, H. A. & Lorenz, R. D. Smoothness of Titan’s Ontario Lacus: constraints from Cassini RADAR specular reflection data. Geophys. Res. Lett. 36, L16201 (2009).

    Article  Google Scholar 

  8. 8.

    Zebker, H. et al. Surface of Ligeia Mare, Titan, from Cassini altimeter and radiometer analysis. Geophys. Res. Lett. 41, 308–313 (2014).

    Article  Google Scholar 

  9. 9.

    Grima, C. et al. Surface roughness of Titan’s hydrocarbon seas. Earth Planet. Sci. Lett. 474, 20–24 (2017).

    Article  Google Scholar 

  10. 10.

    Stephan, K. et al. Specular reflection on Titan: liquids in Kraken Mare. Geophys. Res. Lett. 37, L07104 (2010).

    Article  Google Scholar 

  11. 11.

    Barnes, J. W. et al. Wave constraints for Titan’s Jingpo Lacus and Kraken Mare from VIMS specular reflection lightcurves. Icarus 211, 722–731 (2011).

    Article  Google Scholar 

  12. 12.

    Barnes, J. W. et al. Cassini/VIMS observes rough surfaces on Titan’s Punga Mare in specular reflection. Planet. Sci. 3, 3 (2014).

    Article  Google Scholar 

  13. 13.

    West, R. A., Lavvas, P., Anderson, C. & Imanaka, H. in Titan: Surface, Atmosphere and Magnetosphere (eds Muller-Wodarg, I. et al.) 285–321 (Cambridge Univ. Press, New York, 2014).

  14. 14.

    Tomasko, M. G. et al. A model of Titan’s aerosols based on measurements made inside the atmosphere. Planet. Space Sci. 56, 669–707 (2008).

    Article  Google Scholar 

  15. 15.

    Curtis, D. B. et al. Laboratory studies of methane and ethane adsorption and nucleation onto organic particles: application to Titan’s clouds. Icarus 195, 792–801 (2008).

    Article  Google Scholar 

  16. 16.

    Seignovert, B., Rannou, P., Lavvas, P., Cours, T. & West, R. A. Aerosols optical properties in Titan’s detached haze layer before the equinox. Icarus 292, 13–21 (2017).

    Article  Google Scholar 

  17. 17.

    Rannou, P., Hourdin, F., McKay, C. P. & Luz, D. A coupled dynamics–microphysics model of Titan’s atmosphere. Icarus 170, 443–462 (2004).

    Article  Google Scholar 

  18. 18.

    Rannou, P., Montmessin, F., Hourdin, F. & Lebonnois, S. The latitudinal distribution of clouds on Titan. Science 311, 201–205 (2006).

    Article  Google Scholar 

  19. 19.

    Turtle, E. P. et al. Rapid and extensive surface changes near Titan’s equator: evidence of April showers. Science 331, 1414–1417 (2011).

    Article  Google Scholar 

  20. 20.

    Schneider, T., Graves, S. D. B., Schaller, E. L. & Brown, M. E. Polar methane accumulation and rainstorms on Titan from simulations of the methane cycle. Nature 481, 58–61 (2012).

    Article  Google Scholar 

  21. 21.

    Coustenis, A. et al. Titan’s temporal evolution in stratospheric trace gases near the poles. Icarus 270, 409–420 (2016).

    Article  Google Scholar 

  22. 22.

    Molter, E. M. et al. ALMA observations of HCN and its isotopologues on Titan. Astron. J. 152, 42 (2016).

    Article  Google Scholar 

  23. 23.

    Krasnopolsky, V. A. Chemical composition of Titan’s atmosphere and ionosphere: observations and the photochemical model. Icarus 236, 83–91 (2014).

    Article  Google Scholar 

  24. 24.

    de Kok, R. J., Teanby, N. A., Maltagliati, L., Irwin, P. G. J. & Vinatier, S. HCN ice in Titan’s high-altitude southern polar cloud. Nature 514, 65–67 (2014).

    Article  Google Scholar 

  25. 25.

    Lavvas, P., Griffith, C. A. & Yelle, R. V. Condensation in Titan’s atmosphere at the Huygens landing site. Icarus 215, 732–750 (2011).

    Article  Google Scholar 

  26. 26.

    Couturier-Tamburelli, I., Piétri, N., Le Letty, V., Chiavassa, T. & Gudipati, M. UV–vis light-induced aging of Titan’s haze and ice. Astrophys. J. 852, 117 (2018).

    Article  Google Scholar 

  27. 27.

    Hobbs, P. V., Chang, S. & Locatelli, J. D. The dimensions and aggregation of the ice crystals in natural clouds. J. Geophys. Res. 79, 2199–2206 (1974).

    Article  Google Scholar 

  28. 28.

    Forget, F., Hourdin, F. & Talagrand, O. CO2 snowfall on Mars: simulation with a general circulation model. Icarus 131, 302–316 (1998).

    Article  Google Scholar 

  29. 29.

    Waite, J. H. et al. The process of tholin formation in Titan’s upper atmosphere. Science 316, 870–875 (2007).

    Article  Google Scholar 

  30. 30.

    López-Puertas, M. et al. Large abundances of polycyclic aromatic hydrocarbons in Titan’s upper atmosphere. Astrophys. J. 770, 132 (2013).

    Article  Google Scholar 

  31. 31.

    Stevenson, J., Lunine, J. & Clancy, P. Membrane alternatives in worlds without oxygen: creation of an azotosome. Sci. Adv. 1, e1400067 (2015).

    Article  Google Scholar 

  32. 32.

    Gautier, T. et al. Nitrogen incorporation in Titan’s tholins inferred by high resolution Orbitrap mass spectrometry and gas chromatography–mass spectrometry. Earth Planet. Sci. Lett. 404, 33–42 (2014).

    Article  Google Scholar 

  33. 33.

    Ancheyta, J. & Speight, J. G. Hydroprocessing of Heavy Oils and Residua (CRC Press, Boca Raton, 2007).

  34. 34.

    Sagan, C., Thomson, W. R. & Khare, B. Titan: a laboratory for pre-biological organic chemistry. Acc. Chem. Res. 25, 286–292 (1992).

    Article  Google Scholar 

  35. 35.

    Hörst, S. M. & Tolbert, M. A. In situ measurements of the size and density of Titan aerosol analogs. Astrophys. J. Lett. 770, L10 (2013).

    Article  Google Scholar 

  36. 36.

    Imanaka, H., Cruikshank, D. P., Khare, B. N. & McKay, C. P. Optical constants of Titan tholins at mid-infrared wavelengths (2.5–25 μm) and the possible chemical nature of Titan’s haze particles. Icarus 218, 247–261 (2012).

    Article  Google Scholar 

  37. 37.

    Brouet, Y. et al. A porosity gradient in 67P/C-G nucleus suggested from CONSERT and SESAME-PP results: an interpretation based on new laboratory permittivity measurements of porous icy analogues. Mon. Not. R. Astron. Soc. 462, S89–S98 (2016).

    Article  Google Scholar 

  38. 38.

    Cordier, D. et al. Structure of Titan’s evaporites. Icarus 270, 41–56 (2016).

    Article  Google Scholar 

  39. 39.

    Cordier, D., Garca-Sánchez, F., Justo-Garca, D. N. & Liger-Belair, G. Bubble streams in Titan’s seas as a product of liquid N2 + CH4 + C2H6 cryogenic mixture. Nat. Astron. 1, 0102 (2017).

    Article  Google Scholar 

  40. 40.

    Le Gall, A. et al. Composition, seasonal change, and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission. J. Geophys. Res. 121, 233–251 (2016).

    Article  Google Scholar 

  41. 41.

    Gao, X. & Jiang, L. Biophysics: water-repellent legs of water striders. Nature 432, 36 (2004).

    Article  Google Scholar 

  42. 42.

    Sánchez-Lavega, A. An Introduction to Planetary Atmospheres (CRC Press, Boca Raton, 2010).

  43. 43.

    Barth, E. L. & Toon, O. B. Methane, ethane, and mixed clouds in Titan’s atmosphere: properties derived from microphysical modeling. Icarus 182, 230–250 (2006).

    Article  Google Scholar 

  44. 44.

    Rodriguez, S. et al. Impact of aerosols present in Titan’s atmosphere on the CASSINI radar experiment. Icarus 164, 213–227 (2003).

    Article  Google Scholar 

  45. 45.

    Curtis, D. B., Toon, O. B., Tolbert, M. A., McKay, C. P. & Khare, B. N. Laboratory studies of butane nucleation on organic haze particles: application to Titan’s clouds. Icarus 109, 1382–1390 (2005).

    Google Scholar 

  46. 46.

    Pruppacher, H. R. & Klett, J. D. Microphysics of Clouds and Precipitation (Reidel, Dordrecht, 1978).

    Google Scholar 

  47. 47.

    Courtin, R., Kim, S. J. & Bar-Nun, A. Three-micron extinction of the Titan haze in the 250–700 km altitude range: possible evidence of a particle-aging process. Astron. Astrophys. 573, A21 (2015).

    Article  Google Scholar 

  48. 48.

    Carrasco, N. et al. Chemical characterization of Titan’s tholins: solubility, morphology and molecular structure revisited. J. Phys. Chem. A 113, 11195–11203 (2009).

    Article  Google Scholar 

  49. 49.

    Lorenz, R. D. Physics of saltation and sand transport on Titan: a brief review. Icarus 230, 162–167 (2014).

    Article  Google Scholar 

  50. 50.

    Cordier, D. & Liger-Belair, G. Bubbles in Titan’s seas: nucleation, growth, and RADAR signature. Astrophys. J. 859, 26 (2018).

    Article  Google Scholar 

  51. 51.

    Vincent, D. et al. Numerical study of tides in Ontario Lacus, a hydrocarbon lake on the surface of the Saturnian moon Titan. Ocean Dynam. 66, 461–482 (2016).

    Article  Google Scholar 

  52. 52.

    Kurata, N. et al. Surfactant-associated bacteria in the near-surface layer of the ocean. Sci. Rep. 6, 19123 (2016).

    Article  Google Scholar 

  53. 53.

    Whitesides, G. M. & Boncheva, M. Beyond molecules: self-assembly of mesoscopic and macroscopic components. Proc. Natl Acad. Sci USA 99, 4769–4774 (2002).

    Article  Google Scholar 

  54. 54.

    Soderblom, J. M. et al. Modeling specular reflections from hydrocarbon lakes on Titan. Icarus 220, 744–751 (2012).

    Article  Google Scholar 

  55. 55.

    van den Tempel, M. & van de Riet, R. P. Damping of waves by surface‐active materials. J. Chem. Phys. 42, 2769 (1965).

    Article  Google Scholar 

  56. 56.

    Komen, G. J. et al. Dynamics and Modelling of Ocean Waves (Cambridge Univ. Press, Cambridge, 1994).

    Google Scholar 

  57. 57.

    Phillips, F. T. On the generation of waves by turbulent wind. J. Fluid Mech. 2, 417–445 (1957).

    Article  Google Scholar 

  58. 58.

    Miles, J. W. On the generation of the surface waves by shear flows. J. Fluid Mech. 3, 185–204 (1957).

    Article  Google Scholar 

  59. 59.

    Hofgartner, J. D. et al. Transient features in a Titan sea. Nat. Geosci. 7, 493–496 (2014).

    Article  Google Scholar 

  60. 60.

    Hofgartner, J. D. et al. Titan’s ‘magic islands’: transient features in a hydrocarbon sea. Icarus 271, 338–349 (2016).

    Article  Google Scholar 

  61. 61.

    Lorenz, R. D., Kraal, E. R., Eddlemon, E. E., Cheney, J. & Greeley, R. Sea-surface wave growth under extraterrestrial atmospheres: preliminary wind tunnel experiments with application to Mars and Titan. Icarus 175, 556–560 (2005).

    Article  Google Scholar 

  62. 62.

    Hartwig, J. W. et al. Exploring the depths of Kraken Mare—power, thermal analysis, and ballast control for the Saturn Titan submarine. Cryogenics 74, 31–46 (2016).

    Article  Google Scholar 

  63. 63.

    Cini, R. Damping effect of monolayers on surface wave motion in a liquid. J. Colloid Interface Sci. 65, 387–389 (1978).

    Article  Google Scholar 

  64. 64.

    Weber, J. E. Wave attenuation and wave drift in the marginal ice zone. J. Phys. Oceanogr. 17, 2351–2361 (1987).

    Article  Google Scholar 

  65. 65.

    Jenkins, D. & Jacobs, S. J. Wave damping by a thin layer of viscous fluid. Phys. Fluids 9, 1256 (1997).

    Article  Google Scholar 

  66. 66.

    Lucassen, J. & Giles, D. Dynamic surface properties of nonionic surfactant solutions. J. Chem. Soc. Faraday Trans. 71, 217–232 (1975).

    Article  Google Scholar 

Download references


N.C. thanks the European Research Council for funding via the ERC PrimChem project (grant agreement no. 636829). This work was also supported by the Programme National de Planétologie (PNP) of CNRS-INSU co-funded by CNES. The authors thank S. Lebonnois, J. Vatant d’Ollone, T. Tokano and B. Charnay for fruitful scientific discussions.

Author information




D.C. wrote the paper and performed numerical simulations. N.C. provided expertise concerning the properties of Titan’s aerosols.

Corresponding author

Correspondence to Daniel Cordier.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–3 and Tables 1 and 2.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Cordier, D., Carrasco, N. The floatability of aerosols and wave damping on Titan’s seas. Nat. Geosci. 12, 315–320 (2019).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing