Numerical study of tides in Ontario Lacus, a hydrocarbon lake on the surface of the Saturnian moon Titan
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In the context of the emergence of extra-terrestrial oceanography, we adapted an existing oceanographic model, SLIM (www.climate.be/slim), to the conditions of Titan, a moon of Saturn. The tidal response of the largest southern lake at Titan’s surface, namely Ontario Lacus, is simulated. SLIM solves the 2D, depth-averaged shallow water equations on an unstructured mesh using the discontinuous Galerkin finite element method, which allows for high spatial resolution wherever needed. The impact of the wind forcing, the bathymetry, and the bottom friction is also discussed. The predicted maximum tidal range is about 0.56 m in the southern part of the lake, which is more than twice as large as the previous estimates (see Tokano, Ocean Dyn 60:(4) 803–817 10.1007/s10236-010-0285-3 (Tokano 2010)). The patterns and magnitude of the current are also markedly different from those of previous studies: the tidal motion is not aligned with the major axis of the lake and the speed is larger nearshore. Indeed, the main tidal component rotates clockwise in an exact period of one Titan day and the tidal currents can reach 0.046 ms −1 close to the shores depending on the geometry and the bathymetry. Except for these specific nearshore regions, the current speed is less than 0.02 ms −1. Circular patterns can be observed offshore, their rotational direction and size varying along the day.
KeywordsOntario Lacus Tides Titan Finite element Numerical model Extraterrestrial oceanography
The present study was carried out in the framework of the project “Taking up the challenge of multiscale marine modelling,” which is funded by the Communauté Française de Belgique under contract ARC 10/15-028 with the aim of developing and using SLIM (www.climate.be/slim). David Vincent is a PhD student funded by a grant of the Fonds spéciaux de recherche of the Université catholique de Louvain, Eric Deleersnijder is an honory research associate with the Belgian Fund for Scientific Research (FNRS), Özgür Karatekin is funded by the belgian PRODEX, managed by the ESA, in collaboration with th Belgian Federal Science Policy Office.
We would like to thank N. Guillaume for his previous work as a Master’s degree student at Université catholique de Louvain and the SLIM team for their support.
- Brown RH, Baines KH, Bellucci G, Bibring JP, Buratti BJ, Capaccioni F, Cerroni P, Clark RN, Coradini A, Cruikshank DP et al (2004) The Cassini visual and infrared mapping spectrometer (VIMS) investigation. In: The Cassini-Huygens Mission. Springer, pp 111–168. doi: 10.1007/1-4020-3874-7_3
- Flasar FM, Kunde VG, Abbas MM, Achterberg RK, Ade P, Barucci A, Bézard B, Bjoraker GL, Brasunas JC, Calcutt S et al (2004) Exploring the saturn system in the thermal infrared: The composite infrared spectrometer. In: The Cassini-Huygens Mission. doi: 10.1007/1-4020-3874-7_4. Springer, pp 169–297
- Hanel R, Conrath B, Flasar FM, Kunde V, Maguire W, Pearl J, Pirraglia J, Samuelson R, Herath L, Allison M, Cruikshank D, Gautier D, Gierasch P, Horn L, Koppany R, Ponnamperuma C (1981) Infrared observations of the saturnian system from Voyager-1. Science 212:192–200. doi: 10.1126/science.212.4491.192 CrossRefGoogle Scholar
- Hayes AG (2016) The lakes and seas of Titan. Ann Rev Earth Planet Sci:44. doi: 10.1146/annurev-earth-060115-012247
- Hayes AG, Aharonson O, Callahan P, Elachi C, Gim Y, Kirk RL, Lewis K, Lopes R, Lorenz RD, Lunine JI et al (2008) Hydrocarbon lakes on titan: distribution and interaction with a porous regolith. Geophys Res Lett 35(9). doi: 10.1029/2008GL033409
- Hayes AG, Michaelides RJ, Turtle EP, Barnes JW, Soderblom JM, Masrtogiuseppe M, Lorenz RD, Kirk RL, Lunine JI (2014) The distribution and volume of Titan’s hydrocarbon lakes and seas. In: Lunar and planetary institute science conference abstracts, vol 45, p 2341Google Scholar
- Howarth MJ (2005) Hydrography of the Irish sea Sea6 technical report. Department of Trade and Industry offshore energy Strategic Assessment programme, UKGoogle Scholar
- Lopez Gonzalez T, Bourgeois O, Le Mouélic S, Rodriguez S, Lopez Gonzalez T, Sotin C, Tobie G, Fleurant C, Barnes JW, Brown RH et al (2012) Geomorphological significance of Ontario Lacus on Titan: integrated interpretation of Cassini VIMS ISS and RADAR data and comparison with the Etosha Pan (Namibia). Icarus 218(2):788–806. doi: 10.1016/j.icarus.2012.01.013 CrossRefGoogle Scholar
- Lorenz RD, Lunine JL, Neish CD (2011) Cyanide soap? Dissolved materials in Titan’s seas. EPSC-DPS2011 6:488Google Scholar
- Lorenz RD (2013) Oceanography on Saturn’s moon, Titan. In: Oceans-san diego, 2013. IEEE, pp 1–7Google Scholar
- Lorenz RD, Kirk RL, Hayes AG, Cassini AG, Anderson YZ, Lunine JI, Tokano T, Turtle EP, Malaska MJ, Soderblom JM, Lucas A, et al (2014) A radar map of Titan seas: Tidal dissipation and ocean mixing through the throat of Kraken. Icarus 237:9–15. doi: 10.1016/j.icarus.2014.04.005 CrossRefGoogle Scholar
- Lunine JI, Hayes A, Aharonson O, Mitri G, Lorenz R, Stofan E, Wall S, Elachi C, Cassini Radar Team et al (2009) Evidence for liquid in Ontario Lacus (Titan) from Cassini-observed changes. In: AAS/Division for planetary sciences meeting abstracts# 41 , vol 41Google Scholar
- McEwen A, Turtle E, Perry J, Dawson D, Fussner S, Collins G, Porco C, Johnson T, Soderblom L (2005) Mapping and monitoring the surface of Titan Bulletin of the american astronomical society, vol 37, p 739Google Scholar
- National Oceanic and Atmospheric Administration (2014) Do the Great Lakes have tides. http://oceanservice.noaa.gov/facts/gltides.html, accessed: 2015-08-21
- Porco CC, West RA, Squyres S, Mcewen A, Thomas P, Murray CD, Delgenio A, Ingersoll AP, Johnson TV, Neukum G et al (2004) Cassini imaging science: instrument characteristics and anticipated scientific investigations at Saturn. Space Sci Rev 115(1-4):363–497. doi: 10.1007/s11214-004-1456-7 CrossRefGoogle Scholar
- Sohl F, Hussmann H, Schwentker B, Spohn T, Lorenz RD (2003) Interior structure models and tidal Love numbers of Titan. J Geophys Res-Planet 108(E12). doi: 10.1029/2003JE002044
- Volkov VA, Johannessen OM, Borodachev VE, Voinov GN, Pettersson LH, Bobylev LP, Kouraev AV (2002) Polar seas oceanography: an integrated case study of the Kara Sea. Springer Science & Business MediaGoogle Scholar