TY - JOUR
T1 - GCM simulations of Titan's middle and lower atmosphere and comparison to observations
AU - Lora, Juan M.
AU - Lunine, Jonathan I.
AU - Russell, Joellen L.
N1 - Funding Information:
The authors acknowledge support from NASA Earth and Space Science Fellowship NNX12AN79H , and the Cassini project . Simulations were carried out with an allocation of computing time on the High Performance Computing systems at the University of Arizona. The authors would also like to thank S. Rodriguez and an anonymous reviewer for detailed comments to improve the manuscript, and S. Rodriguez for providing the VIMS cloud observations.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Simulation results are presented from a new general circulation model (GCM) of Titan, the Titan Atmospheric Model (TAM), which couples the Flexible Modeling System (FMS) spectral dynamical core to a suite of external/sub-grid-scale physics. These include a new non-gray radiative transfer module that takes advantage of recent data from Cassini-Huygens, large-scale condensation and quasi-equilibrium moist convection schemes, a surface model with "bucket" hydrology, and boundary layer turbulent diffusion. The model produces a realistic temperature structure from the surface to the lower mesosphere, including a stratopause, as well as satisfactory superrotation. The latter is shown to depend on the dynamical core's ability to build up angular momentum from surface torques. Simulated latitudinal temperature contrasts are adequate, compared to observations, and polar temperature anomalies agree with observations. In the lower atmosphere, the insolation distribution is shown to strongly impact turbulent fluxes, and surface heating is maximum at mid-latitudes. Surface liquids are unstable at mid- and low-latitudes, and quickly migrate poleward. The simulated humidity profile and distribution of surface temperatures, compared to observations, corroborate the prevalence of dry conditions at low latitudes. Polar cloud activity is well represented, though the observed mid-latitude clouds remain somewhat puzzling, and some formation alternatives are suggested.
AB - Simulation results are presented from a new general circulation model (GCM) of Titan, the Titan Atmospheric Model (TAM), which couples the Flexible Modeling System (FMS) spectral dynamical core to a suite of external/sub-grid-scale physics. These include a new non-gray radiative transfer module that takes advantage of recent data from Cassini-Huygens, large-scale condensation and quasi-equilibrium moist convection schemes, a surface model with "bucket" hydrology, and boundary layer turbulent diffusion. The model produces a realistic temperature structure from the surface to the lower mesosphere, including a stratopause, as well as satisfactory superrotation. The latter is shown to depend on the dynamical core's ability to build up angular momentum from surface torques. Simulated latitudinal temperature contrasts are adequate, compared to observations, and polar temperature anomalies agree with observations. In the lower atmosphere, the insolation distribution is shown to strongly impact turbulent fluxes, and surface heating is maximum at mid-latitudes. Surface liquids are unstable at mid- and low-latitudes, and quickly migrate poleward. The simulated humidity profile and distribution of surface temperatures, compared to observations, corroborate the prevalence of dry conditions at low latitudes. Polar cloud activity is well represented, though the observed mid-latitude clouds remain somewhat puzzling, and some formation alternatives are suggested.
KW - Atmospheres, dynamics
KW - Titan, atmosphere
KW - Titan, clouds
KW - Titan, hydrology
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U2 - 10.1016/j.icarus.2014.12.030
DO - 10.1016/j.icarus.2014.12.030
M3 - Article
AN - SCOPUS:84921477068
VL - 250
SP - 516
EP - 528
JO - Icarus
JF - Icarus
SN - 0019-1035
ER -