Search Publications
Modelled isotopic fractionation and transient diffusive release of methane from potential subsurface sources on Mars
Stevens, Adam H.; Lewis, Stephen R.; Patel, Manish R.
We calculate transport timescales of martian methane and investigate the effect of potential release mechanisms into the atmosphere using a numerical model that includes both Fickian and Knudsen diffusion. The incorporation of Knudsen diffusion, which improves on a Fickian description of transport given the low permeability of the martian regolith…
The photochemical fractionation of oxygen isotopologues in Titan's atmosphere
Dobrijevic, M.; Loison, J. C.; Hickson, K. M. +1 more
The origin of CO and the external source of H2O in the atmosphere of Titan is still a matter of debate. We investigated the chemical fractionation of oxygen isotopologues in order to give new constraints on the origin of oxygen species. We created a new chemical scheme and we developed a 1-D time-dependent photochemical model to compute…
The effect of like-charge attraction on aerosol growth in the atmosphere of Titan
Lindgren, Eric B.; Stamm, Benjamin; Chan, Ho-Kei +3 more
The formation of aerosols in the atmosphere of Titan is based extensively on ion-neutral chemistry and physical condensation processes. Herein it is shown that the formation of aerosols may also occur through an alternative pathway that involves the physical aggregation of negatively charged particles, which are known to be abundant in the satelli…
Dawn-dusk difference of periodic oxygen EUV dayglow variations at Venus observed by Hisaki
Leblanc, François; Tsuchiya, Fuminori; Seki, Kanako +8 more
We report a dawn-dusk difference of periodic variations of oxygen EUV dayglow (OII 83.4 nm, OI 130.4 nm and OI 135.6 nm) in the upper atmosphere of Venus observed by the Hisaki spacecraft in 2015. Observations show that the periodic dayglow variations are mainly controlled by the solar EUV flux. Additionally, we observed characteristic ∼1 day and …
Radiative energy balance of Venus: An approach to parameterize thermal cooling and solar heating rates
Kappel, D.; Arnold, G.; Haus, R.
Thermal cooling rates QC and solar heating rates QH in the atmosphere of Venus at altitudes between 0 and 100 km are investigated using the radiative transfer and radiative balance simulation techniques described by Haus et al. (2015b, 2016). QC strongly responds to temperature profile and cloud parameter changes, …
Diurnal observations of HCl altitude variation in the 70-100 km mesosphere of Venus
Todd Clancy, R.; Sandor, Brad J.
First submm spectroscopic observations of the 625.9 GHz H35Cl absorption lines of the Venus dayside atmosphere were obtained with the James Clerk Maxwell Telescope (JCMT) on March 2, 2013. These data, which support retrieval of HCl altitude distributions in the Venus mesosphere (70-100 km), are presented here and compared with previousl…
Clastic patterned ground in Lomonosov crater, Mars: examining fracture controlled formation mechanisms
Balme, Matthew R.; Patel, Manish R.; Hagermann, Axel +1 more
The area surrounding Lomonosov crater on Mars has a high density of seemingly organised boulder patterns. These form seemingly sorted polygons and stripes within kilometre scale blockfields, patches of boulder strewn ground which are common across the Martian high latitudes. Several hypotheses have been suggested to explain the formation of clasti…
The reflectivity of Mars at 1064 nm: Derivation from Mars Orbiter Laser Altimeter data and application to climatology and meteorology
Heavens, N. G.
The Mars Orbiter Laser Altimeter (MOLA) on board Mars Global Surveyor (MGS) made > 108 measurements of the reflectivity of Mars at 1064 nm (R1064) by both active sounding and passive radiometry. Past studies of R1064 neglected the effects of atmospheric opacity and viewing geometry on both active and passive mea…
Discovery of a 150 day period in the Venus condensational clouds
Tsang, Constantine C. C.; McGouldrick, Kevin
We have analyzed the long-term regional and global variation of emitted radiance in 1.74 µ m and 2.30 µ m near infrared spectral windows in the Venus atmosphere using the medium resolution, infrared channel of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS-M-IR) on the Venus Express spacecraft. We find a periodic variati…
Search for HBr and bromine photochemistry on Venus
Krasnopolsky, Vladimir A.; Belyaev, Denis A.
HBr (1-0) R2 2605.8/6.2 cm-1, the strongest line of the strongest band of HBr, was observed when searching for this species on Venus. The observation was conducted using the NASA IRTF and a high-resolution long-slit spectrograph CSHELL with resolving power of 4 × 104. 101 spectra of Venus were analyzed, and the retrieved HBr …