Search Publications
Formation of lobate debris aprons on Mars: Assessment of regional ice sheet collapse and debris-cover armoring
Head, James W.; Fastook, James L.; Marchant, David R.
Lobate debris aprons (LDA) are lobate-shaped aprons surrounding scarps and isolated massifs that are concentrated in the vicinity of the northern Dichotomy Boundary on Mars. LDAs have been interpreted as (1) ice-cemented talus aprons undergoing viscous flow, (2) local debris-covered alpine-like glaciers, or (3) remnants of the collapse of a region…
Global climate modeling of Saturn’s atmosphere. Part I: Evaluation of the radiative transfer model
Forget, F.; Millour, E.; Spiga, A. +8 more
We have developed and optimized a seasonal, radiative-convective model of Saturn’s upper troposphere and stratosphere. It is used to investigate Saturn’s radiatively-forced thermal structure between 3 and 10-6 bar, and is intended to be included in a Saturn global climate model (GCM), currently under development. The main elements of th…
High latitude gravity waves at the Venus cloud tops as observed by the Venus Monitoring Camera on board Venus Express
Markiewicz, W. J.; Titov, D. V.; Peralta, J. +4 more
High resolution images of Venus Northern hemisphere obtained with the Venus Monitoring Camera (VMC/VEx) allow studying small-scale dynamical phenomena at the cloud tops (∼62-70 km altitude) including features like wave trains. A systematic visual search of these waves was performed; more than 1500 orbits were analyzed and wave patterns were observ…
The distribution of methane in Titan’s stratosphere from Cassini/CIRS observations
Lellouch, E.; Flasar, F. M.; Bézard, B. +5 more
Cassini/CIRS spectra in the far- and mid-infrared region are used to determine the abundance of methane in Titan's lower stratosphere and investigate its distribution with latitude. The CIRS spectra include emission from both the CH4 ν4 band at 7.7 µm and pure rotational lines longwards of 50 µm, which show differ…
Inverse insolation dependence of Venus' cloud-level convection
Imamura, Takeshi; Ando, Hiroki; Sugimoto, Norihiko +4 more
It is generally accepted that convection in planetary atmospheres is enhanced in low latitudes and in the daytime where incoming solar radiation is intense. Here we demonstrate, using a local convection model, that this tendency is reversed for Venus' cloud-level convection, which is driven by heating of the cloud base by upwelling infrared radiat…
Aromatic and aliphatic organic materials on Iapetus: Analysis of Cassini VIMS data
Clark, Roger N.; Cruikshank, Dale P.; Pendleton, Yvonne J. +1 more
We present a quantitative analysis of the hydrocarbon and other organic molecular inventory as a component of the low-albedo material of Saturn’s satellite Iapetus, based on a revision of the calibration of the Cassini VIMS instrument. Our study uses hyperspectral data from a mosaic of Iapetus’ surface (Pinilla-Alonso, N., Roush, T.L., Marzo, G.A.…
Elevation distribution of Titan's craters suggests extensive wetlands
Lorenz, R. D.; Neish, C. D.
Using a new global topographic map of Titan, we find that craters on Titan preferentially lie at higher than average elevations. We explore several explanations for this observed behavior, and judge the most reasonable explanation to be the presence of widespread wetlands of liquid hydrocarbons at low elevations over much of geologic time. Impacts…
Valles Marineris dune fields as compared with other martian populations: Diversity of dune compositions, morphologies, and thermophysical properties
Chojnacki, Matthew; Moersch, Jeffrey E.; Burr, Devon M.
Planetary dune field properties and their bulk bedform morphologies relate to regional wind patterns, sediment supply, climate, and topography. On Mars, major occurrences of spatially contiguous low-albedo sand dunes are primarily found in three major topographic settings: impact craters, high-latitude basins, and linear troughs or valleys, the la…
Temperature dependence of the sublimation rate of water ice: Influence of impurities
Kossacki, Konrad J.; Leliwa-Kopystynski, Jacek
The sublimation rate of ice is commonly calculated using the simple Hertz-Knudsen formula. This formula is derived from the kinetic theory of gases and ignores microphysical processes determining the actual sublimation rate. The microphysical processes can be accounted for by including the temperature dependent sublimation coefficient (Kossacki, K…
Volcano-ice interactions in the Arsia Mons tropical mountain glacier deposits
Head, James W.; Marchant, David R.; Wilson, Lionel +1 more
Fan-shaped deposits (FSD) superposed on the sides of the Tharsis Montes volcanic edifices are widely interpreted to have been formed by cold-based glaciation during the Late Amazonian, a period when the Tharsis Montes were volcanically active. We survey the ∼166,000 km2 Arsia Mons FSD using new, high-resolution image and topography data…