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

Nature Geosciencevolume 12pages315320 (2019) | Download Citation

Abstract

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.

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

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References

  1. 1.

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

  2. 2.

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

  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).

  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).

  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).

  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).

  8. 8.

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

  9. 9.

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

  10. 10.

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

  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).

  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).

  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).

  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).

  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).

  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).

  18. 18.

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

  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).

  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).

  21. 21.

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

  22. 22.

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

  23. 23.

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

  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).

  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).

  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).

  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).

  28. 28.

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

  29. 29.

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

  30. 30.

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

  31. 31.

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

  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).

  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).

  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).

  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).

  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).

  38. 38.

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

  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).

  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).

  41. 41.

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

  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).

  44. 44.

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

  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).

  46. 46.

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

  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).

  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).

  49. 49.

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

  50. 50.

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

  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).

  52. 52.

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

  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).

  54. 54.

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

  55. 55.

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

  56. 56.

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

  57. 57.

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

  58. 58.

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

  59. 59.

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

  60. 60.

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

  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).

  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).

  63. 63.

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

  64. 64.

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

  65. 65.

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

  66. 66.

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

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Acknowledgements

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

Affiliations

  1. Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Reims, France

    • Daniel Cordier
  2. LATMOS, UMR CNRS 8190, Université Versailles St Quentin, Guyancourt, France

    • Nathalie Carrasco
  3. Institut Universitaire de France, Paris, France

    • Nathalie Carrasco

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Contributions

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

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Daniel Cordier.

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  1. Supplementary Information

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

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https://doi.org/10.1038/s41561-019-0344-4

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