2009 .

S. Lebonnois, P. Rannou, and F. Hourdin. The coupling of winds, aerosols and chemistry in Titan's atmosphere. Royal Society of London Philosophical Transactions Series A, 367:665-682, February 2009. [ bib | DOI | PDF version | ADS link ]

G. Tobie, M. Choukroun, O. Grasset, S. Le Mouélic, J. I. Lunine, C. Sotin, O. Bourgeois, D. Gautier, M. Hirtzig, S. Lebonnois, and L. Le Corre. Evolution of Titan and implications for its hydrocarbon cycle. Royal Society of London Philosophical Transactions Series A, 367:617-631, February 2009. [ bib | DOI | PDF version | ADS link ]

V. Eymet, R. Fournier, J.-L. Dufresne, S. Lebonnois, F. Hourdin, and M. A. Bullock. Net exchange parameterization of thermal infrared radiative transfer in Venus' atmosphere. Journal of Geophysical Research (Planets), 114:11008, 2009. [ bib | DOI | PDF version | ADS link ]

Thermal radiation within Venus atmosphere is analyzed in close details. Prominent features are identified, which are then used to design a parameterization (a highly simplified and yet accurate enough model) to be used in General Circulation Models. The analysis is based on a net exchange formulation, using a set of gaseous and cloud optical data chosen among available referenced data. The accuracy of the proposed parameterization methodology is controlled against Monte Carlo simulations, assuming that the optical data are exact. Then, the accuracy level corresponding to our present optical data choice is discussed by comparison with available observations, concentrating on the most unknown aspects of Venus thermal radiation, namely the deep atmosphere opacity and the cloud composition and structure.

A. Coustenis, S. K. Atreya, T. Balint, R. H. Brown, M. K. Dougherty, F. Ferri, M. Fulchignoni, D. Gautier, R. A. Gowen, C. A. Griffith, L. I. Gurvits, R. Jaumann, Y. Langevin, M. R. Leese, J. I. Lunine, C. P. McKay, X. Moussas, I. Müller-Wodarg, F. Neubauer, T. C. Owen, F. Raulin, E. C. Sittler, F. Sohl, C. Sotin, G. Tobie, T. Tokano, E. P. Turtle, J.-E. Wahlund, J. H. Waite, K. H. Baines, J. Blamont, A. J. Coates, I. Dandouras, T. Krimigis, E. Lellouch, R. D. Lorenz, A. Morse, C. C. Porco, M. Hirtzig, J. Saur, T. Spilker, J. C. Zarnecki, E. Choi, N. Achilleos, R. Amils, P. Annan, D. H. Atkinson, Y. Bénilan, C. Bertucci, B. Bézard, G. L. Bjoraker, M. Blanc, L. Boireau, J. Bouman, M. Cabane, M. T. Capria, E. Chassefière, P. Coll, M. Combes, J. F. Cooper, A. Coradini, F. Crary, T. Cravens, I. A. Daglis, E. de Angelis, C. de Bergh, I. de Pater, C. Dunford, G. Durry, O. Dutuit, D. Fairbrother, F. M. Flasar, A. D. Fortes, R. Frampton, M. Fujimoto, M. Galand, O. Grasset, M. Grott, T. Haltigin, A. Herique, F. Hersant, H. Hussmann, W. Ip, R. Johnson, E. Kallio, S. Kempf, M. Knapmeyer, W. Kofman, R. Koop, T. Kostiuk, N. Krupp, M. Küppers, H. Lammer, L.-M. Lara, P. Lavvas, S. Le Mouélic, S. Lebonnois, S. Ledvina, J. Li, T. A. Livengood, R. M. Lopes, J.-J. Lopez-Moreno, D. Luz, P. R. Mahaffy, U. Mall, J. Martinez-Frias, B. Marty, T. McCord, C. Menor Salvan, A. Milillo, D. G. Mitchell, R. Modolo, O. Mousis, M. Nakamura, C. D. Neish, C. A. Nixon, D. Nna Mvondo, G. Orton, M. Paetzold, J. Pitman, S. Pogrebenko, W. Pollard, O. Prieto-Ballesteros, P. Rannou, K. Reh, L. Richter, F. T. Robb, R. Rodrigo, S. Rodriguez, P. Romani, M. Ruiz Bermejo, E. T. Sarris, P. Schenk, B. Schmitt, N. Schmitz, D. Schulze-Makuch, K. Schwingenschuh, A. Selig, B. Sicardy, L. Soderblom, L. J. Spilker, D. Stam, A. Steele, K. Stephan, D. F. Strobel, K. Szego, C. Szopa, R. Thissen, M. G. Tomasko, D. Toublanc, H. Vali, I. Vardavas, V. Vuitton, R. A. West, R. Yelle, and E. F. Young. TandEM: Titan and Enceladus mission. Experimental Astronomy, 23:893-946, 2009. [ bib | DOI | PDF version | ADS link ]

TandEM was proposed as an L-class (large) mission in response to ESAs Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere.

F. Forget, F. Montmessin, J.-L. Bertaux, F. González-Galindo, S. Lebonnois, E. Quémerais, A. Reberac, E. Dimarellis, and M. A. López-Valverde. Density and temperatures of the upper Martian atmosphere measured by stellar occultations with Mars Express SPICAM. Journal of Geophysical Research (Planets), 114:1004, 2009. [ bib | DOI | PDF version | ADS link ]

We present one Martian year of observations of the density and temperature in the upper atmosphere of Mars (between 60 and 130 km) obtained by the Mars Express ultraviolet spectrometer Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM). Six hundred sixteen profiles were retrieved using stellar occultations technique at various latitude and longitude. The atmospheric densities exhibit large seasonal fluctuations due to variations in the dust content of the lower atmosphere which controls the temperature and, thus, the atmospheric scale height, below 50 km. In particular, the year observed by SPICAM was affected by an unexpected dust loading around Ls = 130deg which induced a sudden increase of density above 60 km. The diurnal cycle could not be analyzed in detail because most data were obtained at nighttime, except for a few occultations observed around noon during northern winter. There, the averaged midday profile is found to slightly differ from the corresponding midnight profile, with the observed differences being consistent with propagating thermal tides and variations in local solar heating. About 6% of the observed mesopause temperatures exhibits temperature below the CO2 frost point, especially during northern summer in the tropics. Comparison with atmospheric general circulation model predictions shows that the existing models overestimate the temperature around the mesopause (above 80 to 100 km) by up to 30 K, probably because of an underestimation of the atomic oxygen concentration which controls the CO2 infrared cooling.