Search Publications
Incorporation of a gravity wave momentum deposition parameterization into the Venus Thermosphere General Circulation Model (VTGCM)
Brecht, A. S.; Bougher, S. W.; Rafkin, S. +2 more
The gravity wave-drag parameterization of Alexander and Dunkerton (1999) was implemented into a Venus Thermosphere General Circulation Model (VTGCM) to investigate breaking gravity waves as a source of momentum deposition in Venus' thermosphere. Previously, deceleration of zonal jets on the morning and evening terminators in models was accomplishe…
New nitric oxide (NO) nightglow measurements with SPICAM/MEx as a tracer of Mars upper atmosphere circulation and comparison with LMD-MGCM model prediction: Evidence for asymmetric hemispheres
Montmessin, Franck; Bertaux, Jean-Loup; González-Galindo, Francisco +3 more
We report observations of NO nightglow with the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) experiment on board the Mars Express (MEx) spacecraft. NO molecules emit an ultraviolet photon when N and O atoms (produced at high altitude in the thermosphere) recombine. Therefore, this emission is a trace…
A 1-D model of physical chemistry in Saturn's inner magnetosphere
Delamere, P. A.; Bagenal, F.; Fleshman, B. L. +1 more
Water vapor spewed out of Enceladus' geysers spreads across the Saturn system through dissociation, charge exchange, and neutral-neutral collisions. The combined effects of impact ionization by suprathermal electrons, charge-exchange between ions and neutrals, and radial transport of the plasma produce the observed distribution of ions and their t…
Lunar opposition effect as inferred from Chandrayaan-1 M3 data
Shkuratov, Yuriy; Kaydash, Vadym; Korokhin, Viktor +1 more
The shadow-hiding and coherent backscattering enhancement mechanisms are considered to be the major contributors to the brightness opposition effect of the Moon. However, the actual proportions of the mechanisms at different phase angles still remain not well determined. In order to assess the lunar phase function across small phase angles, we uti…
Characterization of middle-atmosphere polar warming at Mars
Forget, F.; Smith, M.; Bougher, S. +3 more
We characterize middle-atmosphere polar warming (PW) using nearly three Martian years of temperature observations by the Mars Climate Sounder. We report the observed structure of PW and share hypotheses as to possible explanations, which have yet to be tested with global dynamical models. In the data, PW manifested between p = 15 Pa and p = 4.8×10…
Experimental investigation into the effects of meteoritic impacts on the spectral properties of phyllosilicates on Mars
Hasegawa, S.; Gavin, P.; Chevrier, V. +2 more
Phyllosilicates have been identified in some of the most highly cratered Noachian terrains on Mars. To study the effects of such impacts on the properties of phyllosilicates, we experimentally shocked six phyllosilicate minerals relevant to the Martian surface: montmorillonite, nontronite, kaolinite, prehnite, chlorite, and serpentine. The shock-t…
Estimates of fluvial erosion on Titan from sinuosity of lake shorelines
Perron, J. Taylor; Tewelde, Yodit; Ford, Peter +2 more
Titan has few impact craters, suggesting that its surface is geologically young. Titan's surface also has abundant landforms interpreted to be fluvial networks. Here we evaluate whether fluvial erosion has caused significant resurfacing by estimating the cumulative erosion around the margins of polar lakes. A scarcity of detailed topographic data …
Evidence for a short period of hydrologic activity in Newton crater, Mars, near the Hesperian-Amazonian transition
Howard, A. D.; Moore, J. M.; Parsons, R. A.
Hesperian/Amazonian-aged valleys and alluvial fans distributed in regional clusters throughout the southern middle- to low-latitudes were formed during a period of fluvial runoff and erosion which acted over a smaller spatial and temporal scale than the older, "classical" Martian valley networks dated to the Noachian-Hesperian boundary. In order t…
Simulations of the latitudinal variability of CO-like and OCS-like passive tracers below the clouds of Venus using the Laboratoire de Météorologie Dynamique GCM
Lebonnois, S.; Marcq, E.
The lower atmosphere of Venus below the clouds is a transitional region between the relatively calm lowermost scale height and the superrotating atmosphere in the cloud region and above. Any observational constraint is then welcome to help in the development of general circulation models of Venus, a difficult task considering the thickness of its …
Exposures of olivine-rich rocks in the vicinity of Ares Vallis: Implications for Noachian and Hesperian volcanism
Mustard, J. F.; Wilson, J. H.
ABSTRACT The igneous evolution of Mars is well represented in stratigraphic settings that transition across major time stratigraphic boundaries. Here we analyze in detail the morphology and composition, determined through visible-near-infrared spectroscopy, of igneous volcanic terrains in Ares Vallis, Mars. Upland plateau units with crater-filling…